Front Brake Kit for Yerf Dog GX150 Estimated Completion Time: 45 minutes
Installation Overview
Installing the Front Brakes Assembly
Install Calipers
Route Brake Lines
Install Dual Master Cylinder
Methods of bleeding the brakes
Recommended Method
Tools Required
- Open-End Wrenches: 8mm, 12mm, 7/16" (Two)
- C-clip Pliers (Optional - See "Methods of Bleeding the Brakes")
STOP - Please Read
Before installing this kit it is required that the front suspension system of the vehicle be upgraded to heavy duty components. The items below must be upgraded.
(Click the links to be taken to our online store, which will open up in a new window.)
Installing the Front Brakes Assembly
A. Install Calipers
1. Mount the calipers to the spindles using the included flange bolts.
Note: The proper way to install the calipers is with the bleeder screw angled UPWARDS and the brake line attachment downwards. View the two pictures below:
(Top Photo) The bleeder screw is mounted upwards (correctly)
(Bottom Photo) The bleeder screws are mounted downwards (incorrectly)
B. Route Brake Lines
2. The two shorter brake lines (27", with springs) are used for each side of the front suspension system. You will notice that one end of the brake line is sharply curved, and the other end terminates at a flat angle. Use the sharply curved ends on the calipiers, and the flat angled ends at the T-split. (see second picture below)
3.
The longer brake line (57") is used to connect the the T-split to the new master cylinder at the rear. Used the sharply curved end at the T-split, and the flat angle end at the master cylinder.
Route brake lines away from any pinch points.
Drill to frame and mount T-split to frame.
B. Install Dual Master Cylinder
4. Unbolt the master cylinder from it's two mounting bolts. Remove the bolts and replace with the longer bolts included in the kit. Position the original and dual master cylinder using the nuts and washers in the kit. Position these items as shown in the third image below.
Unbolt the rear-brake master cylinder (leave it connected to the hydraulic line)
Replace the two master cylinder mounting bolts with the 2-1/2" bolts included in the kit.
These bolts will support the dual master cylinder setup.
Space the bolt shafts as shown using the supplied nuts and washers.
(Note: The picture shows the new master cylinder mounted on the inside near the bracket, but for installation purposes it is easier to install it on the outside, away from the bracket.)
Â
5. Install the new dual fluid reservoir. Use one of the original master cylinder mounting bolts that was removed in step 4. Use the nuts included in the kit, according to the picture below.
C. Methods of Bleeding the Brakes
The usual method of bleeding brakes (pump and release) doesn't work very well on Yerf Dog master cylinders. Vacuum-operated bleeder pumps are a great help and are available at any auto parts store. However, there is a simple way that doesn't require dishing out extra cash for a pump, and can be done with C-clip pliers (or needle nose pliers). We'll flip over the master cylinder and remove the internal piston, allowing gravity to bleed the system while our caliper bleeder screws are open.
Â
6. Start the process by loosely mounting the new (front) master cylinder upside down on it's mounting bolts as pictured below.
7. Disassemble the cylinder by removing the C-clip. The internal piston will spring out enough to allow you to grab and pull it out.
8. Pour DOT-3 or DOT-4 brake fluid into the Front Brake reservoir, filling it to the upper line. Fluid will flow into the master cylinder. Move on to step 9 quickly as the fluid level rises in the master cylinder. Continue to replenish new fluid in the reservoir as the level lowers.
Do NOT pour fluid directly into the open master cylinder. Only pour fresh fluid into the reservoir. This reduces the chance of air bubbles entering the system.
9. When the fluid reaches the top of the master cylinder, insert the piston into the cylinder upside down (with spring facing upwards), just enough to prevent fluid from overflowing from the cylinder while gravity continues to bleed the brakes for us.
10. Open one of the front caliper bleeder screws. You should notice the fluid level in the reservoir diminishing, be sure to replenish the fluid without allowing the reservoir to empty. Within a few minutes, fluid should begin flowing from the caliper bleeder screw. Do not allow the fluid to contact the caliper body or brake pads. It's best to use a small clear hose to direct the fluid flow into a container. Allow the flow to continue until no bubbles come from the line.
11. Repeat the last step with the other front caliper.
12. Reassemble and install the master cylinder, and brake linkages.
13. Check pedal pressure and brake function. With the front-end of the buggy supported, turn the wheels by hand and check that the front brakes work by depressing the brake pedal. The wheels should firmly and abruptly stop.
This article has been downloaded 9,187 times
1 comments about this article:
Instructions coming soon, but the diagram is available now for download.
These instructions must be followed to maintain the 2-Year Engine Protection Guarantee offered bundled with specially advertised products. Even if your engine isn't covered under the guarantee, you should still stick to these tips, as they will prolong the life of your engine and performance. This installation and maintenance guide follows common sense and is straight forward. However, since we are offering our 2-year guarantee for very little or no charge over the normal UNI Kit price, we simply ask that these directions be followed.
Note: The special UNI Oil must be used, or the filter will not be effective. K&N or motor oil will NOT work, as UNI oil is a tacky formula specifically designed for the large pores of the UNI filter. Use of no oil, or use of a different type of oil will void the guarantee.
Oiling the UNI filter elements
1. Remove the UNI filter kit assembly from any packaging.
2. Remove the outer red element from the main filter assembly.
3. Lay out a clean container below your workspace, to capture any oil excess so that you can save it for later use.
4. Very generously pour the special UNI Filter Oil over the red filter element.
5. Use your hands to evenly distribute the oil and work it fully into every pore of the filter element.
-Note: It is very important to pack oil FULLY into the element. Excess will be squeezed out later. Not enough oil will cause engine damage. It is better to have too much than not enough.
6. Form the element into a ball shape and squeeze all of the excess oil out of the filter. Do NOT "wring" the filter, as it will become loose and quickly fall off of the filter assembly while riding.
7. Repeat steps 4-5 on the gray/black filter element. Pour oil INSIDE of the element assembly as well and work the insides. Distribute evenly.
8. Since there is a spring in the gray element, you will need to compress the element the long way to squeeze out the excess oil. Do this several times, wipe away any excess that does not drip off.
9. When you are finished squeezing the excess from both elements, there should be a light amount of oil remaining in the filter. To non-oily hands, all surfaces of the filter should feel "damp" to the touch. If your filter drips after 10 minutes of sitting, you need to squeeze out more oil.
Note: Excessive amounts of oil in the filter will cause restricted performance initially, but will eventually clear up. Too much oil is better than too little. If you feel the filter is too dry, add a little more. If at any time you feel that you need advice about the oiling procedure or amount, contact us.
Installing the UNI filter
1. Oil both filter elements as outlined above.
2. Completely remove your original airbox assembly, leaving vacuum lines from cylinder head, and from rear transmission.
3. Mount the UNI kit directly to the carburetor throat. Carefully tighten hose clamp. Avoid over-tightening the clamp.
4. Secure the UNI kit to the upper engine frame with a large zip-tie (not included). This will depend on the model of buggy you have, however you must secure it in a fashion that inhibits vibration.
5. Avoid ALL sharp objects and corners that will vibrate against the filter elements. Over time semi-sharp objects will cut through the filter due to vibration. Rubbing against a section of round or flat frame should be OK, but use common sense. If the filter tears or rips, the guarantee will be void.
6. Check for any looseness or vibration of the element. Secure if needed. It should not shake around, or it may lead to eventual separation of the element from the base.
Note: The two vacuum lines (one from the valve cover, and the other from the final transmission) will need to be secured away from the exhaust and drive chain. As far as the operation of the engine is concerned, you can allow these hoses to hang without any ill effects. It is common to install our small inline fuel filters at the end of the lines for an extra level of protection. However, to be in compliance with the law you may need to install a catch can or other emissions control device. Refer to your local, state, and/or federal emissions laws for the appropriate measure.
Filter Element Maintenance
- Inspect your UNI Filter before each ride, per the steps below this section.
- Wash and re-oil the filter at least once every 6 months that the vehicle is in operation.
- Do not allow mud, dirt, or other debris to accumulate on the filter element. Wash the filter if an excess of dirt/debris accumulates on the element surface.
- It is normal for the filter element to be a stained dark red color after riding the trails, even after a fresh wash. However, if your element is very brown or caked with dirt, this not normal and will void the guarantee.
Inspecting the UNI filter and Intake System
Inspect your UNI Filter before each ride.
1. Check the filter element for rips or tears. Tears rarely occur, but it does happen if something sharp strikes or vibrates against the filter.
2. Check for any looseness or vibration of the element. It should not shake around, or it may lead to eventual separation of the element from the base.
3. Check the tightness connections from the element to the carburetor. Tighten if needed.
Washing the UNI filter elements
Note: Oil should be properly disposed of in accordance with local, state, and federal law.
1. Create a workspace to capture the oil wash mixture as you perform the wash.
2. Pour a liquid dish detergent on to the filter. Detergents advertising anti-grease properties work excellent. Work the detergent into the filter.
3. Apply warm water to rince the detergent/oil from the filter.
4. Repeat steps 2-3 until no or very little oil is ejected from the filter.
5. Allow the filter to dry, and RE-OIL THE FILTER BEFORE REINSTALLING.
This article has been downloaded 9,187 times
4 comments about this article:
A much improved version of the Dazon Raider Classic wiring diagram, with a explaination of the electrical parts to boot!
Click the diagram to the right of this page to download the full image.
Dazon 150cc Ignition components
The Stator Assembly - CDI power winding
The Dazon Raider 150cc is fitted with the standard AC-fired ignition setup. A single winding on the stator is dedicated to powering the CDI. On most GY6 stators, the CDI-power wire is the Black/Red wire coming from the stator - with a "bullet" style connector.
Magnetic trigger pulse pickup sensor
The "trigger pickup" is mounted above the flywheel and stator assembly, and also has a "bullet" style connector. The pickup wire is typically blue/yellow. This pickup sends a pulse of energy to the CDI as the magnetic nodule on the flywheel passes with each rotation of the flywheel. This is responsible for the timing of the ignition system. Barely any voltage is required from the pickup. If your voltmeter reads 0.0vAC from the pickup wire, you have a bad pickup sensor and a new stator assembly is required.
CDI Ignition Box
CDI stands for "CAPACITIVE DISCHARGE IGNITION".
The CDI is the "brain" of the Dazon 150cc ignition system. It stores energy provided by the stator, and releases that energy to the next step of the ignition system (ignition coil) when it senses voltage from the trigger pickup.
Minimum Output Voltage: 16 vAC
[Typically Solid Purple or Blue, leads directly to ignition coil]
Get it here: CDI for 150cc Engines
Ignition Coil
The ignition coil accepts incoming voltage from the CDI box, and steps the voltage up thousands of times (upwards of 27,000 volts). This high voltage is required to force the electrical energy to jump across the sparkplug gap.
2. Remove (8) 8mm bolts holding CVT cover to crankcase. Carefully remove CVT cover; Go slowly, as the gasket can be easily be destroyed. It is best to carefully slide a flat blade screwdriver between the cover and gasket material to separate them. We have replacement gaskets in stock if yours is destroyed.
3. With the cover off, you can see the variator (unit with fins), driven clutch pulley (unit with 6 holes), and belt. Remove the variator and clutch nuts. They are both 19mm. The minimal force needed to remove these nuts is 40ft/lbs -- It is best to use an air impact wrench. If an air impact wrench is not available, use a large strap wrench to hold the unit steady while loosening bolt.
WARNING: DO NOT hold the cooling plate in place by jamming items through the fins; this will most certainly result in broken fins and other damage to the cooling plate.
4. Remove belt, variator, and clutch pulley.
5. Drain gearbox oil at this time. With the oil drained, remove the (6) 8mm bolts on the Final Gear Case Cover. To remove the Final Gear Case Cover, very carefully tap it away from the crank case with a hammer. This will take patience, as the gear case gasket is easy to destroy. When you have enough clearance between the crankcase and cover, very slowly slide a screwdriver between the cover and gasket and then pull cover away. We have replacement gaskets in stock if yours is destroyed.
6. You should now see the final gear case internals. Pull out the output shaft (The shaft positioned farthest to the rear of the entire assembly) and gear. The counter shaft may fall out, but just sit that aside.
7. If the new output shaft you received in the kit does not have a C-Clip, remove the clip from the original output shaft and install onto new shaft. Place the final gear onto the new output shaft supplied with the kit, and place the new output shaft into the transmission housing.
8. Assemble transmission and CVT in the reverse order of disassembly.
This article has been downloaded 9,187 times
2 comments about this article:
Instructions on how to prepare for the much larger (Super) bolts in our BDX HD GY6 Mount Kit for Honda Ruckus NPS50.
Preparing your frame bushing to accept our BDX 5/8" super bolts is pretty easy. Actually, it can be adequately summed-up in about 3 steps. Let's get started!
You should only need a 7/16" drill bit. However, if your this if your first time performing this upgrade, a 15/32" and/or 1/2" might be needed as well depending on your learning curve for the proper technique. The rotary file pictured most likely won't be needed, but is a handy last resort. The bits all need to be new or very sharp. You can most likely do this with the frame still on the bike, but it's easier with the frame in a table vice.
1. Start drilling with the 7/16". The isolator bushing will begin heating up. Go very slow and easy until about half way down, we don't want too much of a heat differential in the rubber. Don't worry about cooling the bit, it's counterproductive in this situation and the sleeve isn't hardened so the bit won't catch very much extra wear at all. Just a mention in case you were wondering, keeping sharp bits is a big deal around here for production purposes, but you might not be too particularly concerned either way.
2. Once you get about half way, run the drill as fast as possible through the rest of the sleeve an begin applying pressure slightly. This should heat up the sleeve enough for the rubber to let go and spin out.
3. If the inner sleeve doesn't come out in one pass, step up to the next size drill bit and repeat from step 1.
4. The hole you end up with is slightly less than 5/8", which provides a perfect interference fit for our 5/8" bolt. When assembling the bolts to your BDX GY6 Mount, be sure to use Loctite 272 or similar "permanent" thread locker on the threads. Even though it is designated as permanent, don't worry, you will be able to remove the bolt later with at least a good 12" or longer socket wrench.
Congrats, you've been supersized!
This article has been downloaded 9,187 times
0 comments about this article:
This simple explanation reveals how to crack the code and tell what engine you have.
So you found a code on your buggy or scooter and you're wondering what it means. The code can actually tell you a lot about a specific engine.
You can find your engine code below the CVT cover, beside the oil drain plug.
We'll take a look at the most common engine code: 157QMJ.
The first thing to note is that the actual code always starts with the first number, and continues for a total of 6 digits. Anything extra is a manufacturer-specific information that won't be covered here at this time.
Lets disect the code starting with the first digit:
(Digit #1) Corrasponds to the number of cylinders. All GY6 engines are single cylinder, so this number will always be 1.
(Digit #2 and #3) This is the bore size in metric millimeters, in the case of the 157QMJ, our bore is 57mm. Note that 57.4mm bore engines fall under the "57" designation.
(Digit #4) relates to the style of engine. All GY6 engines are designated "Q".
(Digit #5 and #6) The actual size of the engine. The second letter ascends consecutively for each 10cc. MB = 50cc, MC = 60cc, MD for a 70, MH = 110cc, MI = 125cc, MJ = 150cc
That is pretty much it for the standard codes stamped on most GY6 and other Chinese engines. We will add more information about manufacturer-specific codes as we find it out.
Feel free to post your engine code or any additional information below in our comments box, we'll add any new information here!
We frequently receive questions about how the auto-choke and its operating needle work. As it turns out, the auto-choke isn't a choke at all. That is, it doesn't choke airflow through the carburetor like you would find on a lawnmower or generator type of engine. Instead, it sends extra fuel through the carburetor. This is called an enrichment circuit.
This circuit is controlled by the charging system. When your engine is off, the choke (enrichment circuit) is actually "on" in it's default resting state. When the engine is turned on and voltage is applied to the choke, the needle extends and eventually plugs the enrichment ports within the carburetor. This happens within a couple of minutes as the engine warms up.
What we usually see with a bad auto-choke is that the engine will start up and run great cold, but as the engine warms up there will be problems driving, starting, and/or idling.
To test your auto-choke:
1. Remove choke assembly from the choke holder on the side of the carb. The needle should be clearly visable.
2. Measure the overall length of the choke from end-to-end, including the very tip of the needle.
3. Now connect the choke's electrical leads to a 12v power source. Black is negative.
4. Wait 5-10 minutes and re-measure. The needle should have extended.
5. The overall length should be approximately 3mm more than before.
If you need an auto-choke or other related parts, we have them available here:
Q. I can’t remove the clutch (or variator) nut, is it reverse thread?
A. No, they are both standard thread. An impact wrench is best used to take these off.
Q. How do I remove the odd nut that holds on the starter clutch?
A. That is a “spanner” nut. To get it off properly you will need the correct spanner wrench. However, we use a punch and hammer here to remove the nut and replace it with a new one afterward. Remember it’s a reverse thread so turn right to remove.
Q. Something in the rear of my buggy makes a loud “BANG” when I’m accelerating fast or climbing hills, is that the sound of my gears skipping teeth in the transmission?
A. If the gears in your transmission "popped" out of place even once, there would be some pretty impressive internal damage. That loud bang you’re hearing is the chain skipping a tooth on the driver sprocket and slamming back down on the next tooth. First, check the tension on your chain. If tension seems fine then the skipping chain is most likely caused by a flex of the tensioning components when under load. Checklist: Fatigued stock chain tensioner, worn motor mount bushings, stretched chain.
Q. My buggy idles great but when I step on the gas it dies before moving, what might this be?
A. Most likely an intake leak. Check your vacuum lines and intake manifold for cracks or other leaks. Most specifically the vacuum line that connects from side of the carb to the intake manifold.
Q. When I try to start the engine I hear a grinding noise but the engine doesn't start, is my starter bad?
A. Most likely your starter and the internal starting gear are just fine. The usual culprit behind this grinding noise is the starter clutch on its way out.
We currently offer two types of 150cc GY6 engine. One with reverse and one without. We receive a lot of calls asking about installing our engines on a variety of buggies and other vehicles. The intent of this article is to share what we know at this point about installing in various buggies. There may be more issues that aren't listed below. This page will be updated as we find out more. We haven't been able to confirm some of the information, so please take this with additional consideration and research. Use of this information is at your own risk.
Installing GY6 engine (no reverse) into a Yerf Dog GX150, Tomberlin Crossfire 150 (except 150R), Baja Dune 150, and others with 150cc HOWHIT engine
This install is very straight forward. There are no compatiblilty issues. Please read the notes in our engine listing regarding the additional features (kickstart, etc) that our engine offers. If you're interested in adding our reverse kit, you will be pleased to know that this engine comes with the longer output shaft, allowing you to simply bolt the reverse kit on without having to disassemble the engine and transmission to swap shafts. To use the engine without a reverse kit, a spacer comes with the engine so that you can use your original drive sprocket.
How-To:
No step-by-step how-to guide is available at this time.
Installing GY6 engine (no reverse) into a buggy that already has reverse (non-HOWHIT)
If your buggy comes with reverse from the factory, but isn't made by HOWHIT, you can use our no-reverse engine. You will need to transfer your existing reverse components over to the new engine.
Notes:
If your buggy has dual drive chains, the output shaft may not be long enough to support your gearbox.
On non-HOWHIT engines, the new kickstart feature might not be useable
as the lever may hit your frame.
How-To:
No step-by-step how-to guide is available at this time.
Installing GY6 engine with internal reverse into a Yerf Dog GX150 (150cc go-kart)
We are familiar with this swap. The BDX axle will need to be used in order to align the drive sprockets. Also a new chain tensioner (rear motor mount) bracket will need to be fabricated, along with a shifter linkage.
If you would like us to develop a kit in the future for this swap, please contact us and let us know!
Notes:
The drive sprocket on the GY6 Engine w/ is located 2” away from the original location
Given the new sprocket location, the BDX HD Axle must be used for proper sprocket alignment
A reverse shifter and linkage must be fabricated for gear selection
We carry reverse cables and reverse shifters in our online store
A new chain tensioner must be fabricated, which we will offer for sale soon.
No step-by-step how-to guide is available at this time.
Installing GY6 engine with internal reverse into a Yerf Dog CUV (150cc dump-body utility vehicle)
We don't have a Yerf CUV here to test, so we aren't 100% sure on the accuracy of this info. Below are what we believe are the main points of the installation. We know that the original CUV drive sprocket is not compatible with our Internal Reverse GY6 engine. We are working on getting the correct sprocket in stock, we believe the correct sprocket comes as an original replacement part from Tomberlin, on the Crossfire 150R. We haven't been able to confirm this though.
Dimensions on the sprocket are as follows:
Spline count: 24
Spline Diameter: 1.5"
Sprocket Type: Dual Row
Sprocket Teeth Count: 16
Notes:
The original CUV drive sprocket is not compatible with the GY6 engine with internal reverse.
The shifter yoke is in a different location on this engine than the original (see picture). A new linkage will need to be fabricated to connect the shifter to the yoke.
There may be an issue with where the idler sprocket mounts.
Items required:
GY6 GY6 engine with internal reverse
New drive sprocket (see above for dimensions)
How-To:
No step-by-step how-to guide is available at this time.
Installing GY6 engine with internal reverse into a Crossfire 150R (with reverse from the factory)
We don't know much about installing into the Crossfire 150R other than what is noted below:
Notes:
The shifter yoke for the reverse gearcase is in a different location. A new linkage will need to be fabricated.
A new chain tensioner (rear motor mount) will need to be fabricated.
How-To:
No step-by-step how-to guide is available at this time.
This article has been downloaded 9,187 times
2 comments about this article:
A detailed diagram and instructions that show how to rewire the CUV harness to accept a common GY6 CDI, eliminating the larger unit that comes stock.
The Yerf Dog Rover and Scout models come with a CDI from the factory that is not interchangeable with the standard style of CDI. This puts CUV owners in a tough spot when it comes time to replace a failing CDI.
A Performance CDI will also work in place of the standard CDI. Also, if you are good at electrical work and want the full potential of your electrical system, the 11-pole stator and HD regulator can also be used. To use the 11-pole stator this rewire mod will have to be combined with the 11-pole rewire.
This diagram and article is provided for informational purposes. Perform this modification at your own risk, we will not be held responsible for any damages that occur from performing this modification. We will not take returns on stators or CDI's used in this rewire.
This article has been downloaded 9,187 times
1 comments about this article:
A guide explaining how to properly select jet sizes, and installation on PD24J carburetors.
Sizing at sea level:
With UNI filter 120-125
With UNI filter and low restriction exhaust 130-135
With UNI filter, low restriction exhaust, A12 cam, performance coil & CDI and NGK Iridium spark plug 135-140
Test procedure:
1. Run engine at less than half throttle a minimum of 15 minutes to close electric choke
2. On a 300' or 100 meter stretch or greater, run the engine at wide open throttle
3. While still holding the gas pedal to the floor, cut the ignition
4. Remove the spark plug and inspect end for color
a. White - Increase jet size
b. Tan/Brown - Correct jet size
c. Black - Decrease jet size
5. Clean spark plug with brass wire brush and check the gap prior to next test run
Hints:
1. Change jet size by 2 or 2.5 for fine adjustment by 5 for coarse adjustment
2. Reduce jet size by 2 or 2.5 for every 1500 ft or 500 meters of elevation
3. Stock fuel delivery may not be sufficient above a 130 main jet and may require larger diameter fuel lines and less restrictive fuel filter
4. Once main jet is selected, the air/fuel mixture screw can be adjusted for optimum idle
Below is the latest version of the reverse kit install guide (v5.0). This guide covers installation of the new silver/grey reverse kit being shipped after May 1, 2008.
An online version of the guide will be available soon, right here on this page.
This article has been downloaded 9,187 times
0 comments about this article:
A detailed explanation of engine displacement and the relationship of "bore x stroke" to the power production of your engine. Displacement calculator included!
If you're here for the GY6 displacement calculator, click here to jump directly to it.
What is displacement?
The size of a piston-driven gasoline engine (like the GY6 in our buggies) is measured by displacment of it's internal combustion chamber. The term displacement literally
refers to the volume of space the combustion chamber "displaces", and is usually measured in cubic centimeters (cc's).
Displacement, there's no replacement!
The reason displacement is so important in engine design is that in general there is
a direct relation between the amount of displacement, and the amount of power ultimately produced by the engine. There are a lot of other factors, but as the old saying goes: "there's no replacement for
displacement!"
Just like when measuring the internal volume of any cylinder (like a can of Cola, which is 355cc by the way), displacement of an engine is determined by the bore size (diameter) and stroke
length (depth).
Bore size is simply a measure of the piston diameter. The stroke length is how far the piston itself travels inside of the cylinder. For example, the standard bore of
a 150cc GY6 piston is 57.4 millimeters, and the piston travels 58 millimeters within the cylinder every cycle.
Bore x Stroke = Power!
The more displacement an engine has, the more air and fuel mixture it can suck in from the carburetor. The more gas and air you can confine into a space and ignite, the bigger the boom!
This translates to more power at the wheels of your buggy. The internal volume of the engine can be upped by either increasing the bore or the stroke sizes. While these both do the same thing, they are
not created equal. This leads us to the next point...
Why strokers are important.
Stroked engines not only have a larger displacement than a stock engine, but there is also a greater amount of torque produced per additional CC when compared to only a bigger
bore. This is because a stroker crank produces more leaverage than a stock crank. Think of it like this, it is much easier to remove a stubborn rusty bolt with big wrench than with a small wrench,
right? A bigger wrench will take that bolt off easier because your hand travels in a larger diameter circle, resulting in more torque being applied directly
to that stubborn bolt. It's all about leaverage and the same principle applies to the crank shaft of your buggy. A longer stroke means that the piston (your hand) has an easier time turning the crankshaft
(the wrench) and ultimately the rear tires (the bolt). Got it? Cool, we're ready to start playing with numbers...
Calculating displacement.
So you've read everything above (or maybe not...) and you want to see what the actual displacement of your GY6 engine is. That's good, because we happen to have written this nifty little displacement calculator
to hook you up with exactly the info you're after. Here you will find all of the bore and stroke options currently available in the GY6 market, so that you can see all possible displacements with a few
clicks of the mouse.
GY6 Displacement Calculator
Choose an available GY6 bore diameter:
Choose an available GY6 stroke length:
The Result:
The displacement of your GY6 is: 150.09cc!
A. Getting ready. 1. If you are installing STAGE 2 11-pole stator, disconnect the battery.
8-pole stator install does not require the battery to be disconnected.
Note: A flywheel puller will be needed to remove the stock flywheel. Found HERE!
B. Removing stator.
1. Locate the black cooling shroud covering the cooling fan on the passenger-side of the engine. Remove this cover ([2x] 8mm hex bolts, [2x] 7mm hex screws).
2. Remove fan.
3. Remove flywheel nut. An impact wrench may be needed.
4. Using flywheel puller, remove flywheel.
5. Remove stator assembly and trigger wire pickup. Take note to how the wires are routed under the clamp.
C. Installing the new stator.
1. Install the new stator, route wires under clamp. Do not clamp the wire leading to the trigger wire pickup. Install trigger wire pickup.
2. Position the new flywheel over the stator. Rotate the flywheel until it slides onto the shaft, it's inner magnets should pull it over the stator. Check that no wires are touching the flywheel. Any wires
allowed to touch the flywheel will be frayed and severed within minutes of riding.
3. Re-assemble in reverse order of disassembly. D. The re-wire for 11-pole stators. If you are installing a 8-pole stator, please disregard the following instructions.
1. Disconnect original rectifier and cut rectifier plug from away harness. The new rectifier will be wired
in it's place.
2. Please refer to attached diagram.
3. Attach the yellow wires from the stator, to the rectifier. They can be used in any arrangement.
4. Attach green from rectifier, to black bundle in the engine wiring harness.
5. Attach red from rectifier, to red bundle in engine wiring harness.
6. Attach green from stator, to black bundle in engine wiring harness.
---
Note: The "black bundle" in the above steps refer to ground. Any solid grounding point is fine.
Also, the "red bundle" refers to the main power distribution point for running accessories to be powered by rectified/regulated stator output.
---
7. Locate the yellow wire (with red tracer) from the original rectifier plug, and attach it to the red bundle in the engine harness. Make sure your headlights lights are disconnected or they will immediately start pulling power from the battery. In this system, a switch will need to be used to turn off the headlights when not in use.
8. Disconnect the auto choke. Remove red wire pin from it's plug (using an ice pick or similar tool to press down the pin lock inside the plug). Attach wire from rectifier to purple wire pin, wrap connection in electrical tape. Re-connect the auto-choke plug (with purple wire still in place).
F: Problems after installation?
Here are a few specs to help troubleshoot any problems that may occur. Please see below.
11-Pole stator, voltages from stator harness at idle.
With all wiring correctly installed: Attach ground lead of multimeter to the green wire coming from the stator, and the positive meter lead to one of the three yellow wires coming from the stator:
Two of the yellow wires should read: Minimum 14vAC
and the third yellow wire should read: Minimum 7vAC
This article has been downloaded 9,187 times
4 comments about this article:
A diagram and description for installing the BDX Diamond-Plate Fender Kit on the Yerf Dog GX150.
Fender Kit Installation: A. Checking the parts. 1. Open up the box of parts and check to make sure the following was included:
2x Front Fenders (Driver side/Passenger side)
2x Rear Fenders (Driver side/Passenger side)
2x Front mount bracket assemblies
4x 1.5" clamps
2x 4" shanks for upper rear mount w/ 3 nuts each
2x 1-1/8" u-clamps
4x 4" Rubber isolation tape pieces
2. If a small part is missing (nut, washer, etc.), it may have possibly come loose during shipping and traveled into the packing materials. Please check the box thouroughly.
B. Mounting the rear fenders.
1. Mount the two rear clamp assemblies on the bar below the rear cargo rack, use the rubber isolator between clamp and frame.
Please refer to attached diagram for positioning.
2. Remove third nut from rear clamp and insert threaded shaft into the corresponding hole in the rear fender. Re-attach nut to shaft, under fender.
3. Attach U-bolts.
4. Adjust rear fenders to desired position.
C. Mounting the front fenders.
1. Mount front clamp assemblies to the frame section above the front tire, use the rubber isolator between clamp and frame.
Note: Please be careful when tightening the clamps. The clamps will break if over tightened! These clamp mounts were selected to break away if the fenders are impacted by an object (tree, etc.) while riding. This will protect the fender from being damaged on impact.
2. Remove bolt (with two yellow-zinc washers) from assembly. Mount fender with this bolt - a washer on each side of fender.
3. Adjust per attached diagram.
D. Check tightness
1. Rear fenders should have no movement or play.
2. Front fenders should feel solid when pressed down, only moving from play between rubber isolator and clamp.
This article has been downloaded 9,187 times
2 comments about this article:
A diagram and description detailing stock axle removal and BDX Heavy Duty axle installation.
Important note: The new axle bearings included in this kit will need to be positioned properly to eliminate sideplay from the axle assembly. If you look at the new bearings you will see that there are sleeves on both sides of bearing. On one side of the bearing the sleeve will be longer and have 2 set screws. When assembling the bearings on the axle they both need to be positioned facing the same direction, both set screw sleeves should pointing in the same direction, either both left or both right. If after doing this, the bearings are now too tight to bolt down fully: use the included (3) washers between one of the bearing mounts and the frame. See the picture near at the bottom of step D.
Parts List:
1x Axle shaft
2x Sprocket/rotor hubs
2x Wheel Hubs
1x Pack of wheel studs & nylock wheel nuts
2x Axle-end washers
(Cotter pins have been removed from the kit now that we're including nylock axle nuts)
A. Before starting.
1) Lift rear end of buggy and support. The rear tires must be off of the ground during the installation process.
B. Stock axle removal.
1) Unbolt and remove rear wheels from hubs (four nuts on each side).
2) Use needle-nose pliers or a similar tool to disconnect chain master link. Remove chain.
3) Unbolt axle bearing flanges on both sides (3 bolts per flange).
4) Pull each bearing away from the frame and remove axle.
C. Reclaiming the rotor & sprocket.
1) Remove cotter pins from each side of axle.
2) Unbolt and remove rear hubs.
3) Unbolt and remove sprocket and brake rotor.
D. Getting the new axle ready.
1) Remove new axle from box.
2) Remove wheel hubs from axle.
3) Remove sprocket/rotor hubs and hub locks.
4) Thread supplied wheel studs into wheel hubs. Torque to 10 ft/lbs. (4 studs per hub)
5) Attach sprocket and rotor to their respective hubs using bolts from original assembly. (See assembly image for the parts locations.)
6) Slide bearings onto axle shaft.
E. Final assembly.
1) Re-install axle in reverse of step B, with the above picture in mind.
2) Before installing the chain, the axle sprocket will need to be adjusted into place, then locked with the supplied locking collars.
3) When tightening the hub locks, be careful not to over tighten. Once the bolt has made contact with the axle splines, turn approximately a third rotation until the bolt is snugly fit.
This article has been downloaded 9,187 times
0 comments about this article:
Detailed guide to removing and installing the camshaft on a GY6. Covers valve timing, valve adjustment, and finding top dead center.
A. Before installation
1) Wash the entire buggy. This will keep dirt from falling where you don�t
want it while the engine is exposed.
2) Remove the passenger seat from vehicle.
3) Make sure the engine is cold.
B. Access Camshaft assembly
1) Loosen the intake tube at the carburetor and remove the airbox and tube
assembly.
2) Remove black plastic fan shroud from passenger side of motor. (Seven 8mm
screws/bolts)
3) Remove carburetor and air intake boot from motor as a unit and place on
a clean surface. Force may need to be applied to remove intake boot from engine
if it binds. (Two 10mm nuts)
Note: Fuel line will need to be clamped to avoid dumping fuel.
Note: Insert a small clean rag into the intake hole to keep dirt from falling
into the engine.
4) Remove plastic shroud from top of motor to gain access to
cam chain tensioner. The lower shroud does not need to be removed.
Finding Top Dead Center
What is TDC? Top Dead Center refers to the piston being at the very top of
its travel in the cylinder. On a four stroke, TDC will occur at the top of
the compression stroke and the top of the exhaust stroke.
5) Remove sparkplug.
6) Move Flywheel until (T) mark is aligned with the arrow mark on the engine
case.
7) Loosen four valve cover bolts and remove the valve cover.
8) Now that you
are inside the valve cover, rotate the flywheel until the cam is at the TDC
position with hash marks aligned straight across the valve cover surface and
the large TDC hole at the top of the cam gear. (Large TDC hole should be pointing
directly towards seats)
Note: Document TDC on the flywheel using permanent ink; reference your mark
to a point on the engine case.
C. Remove Camshaft
1) Remove the cam chain tensioner by removing the 2 bolts that secure it to
the cylinder. Unless you have a spare, you will need to reuse the gasket. Use
a razor blade to properly separate the gasket from the tensioner.
2) Remove
the 4 head bolt nuts from the rocker tower and remove it.
3) Remove cam chain by tipping the cam gear downwards.
Caution: Be
sure not to drop the cam chain down into the case. The case may need to
be split to refit it.
4) Secure the cam chain with a cord or rope tied to a part of the chassis so
it can be accessed on reassembly.
D. Reassembly
1. Insert the new cam by again tipping the cam gear down and attaching the
cam chain making sure the alignment is set to the mark you made on the flywheel
and the hash marks on the cam, with the large cam hole pointing at the seats.
2.
Install the cam tower back onto the cylinder studs with the EX towards the
exhaust valve (downward).
3. Install the head stud nuts and torque to 1st
16 lbs then on to 25 lbs using a cross pattern.
Note: The Yerf Dog manual states 16lbs on these nuts, however they come from
the factory tourqed to 25lbs.
4. Recheck the cam alignment chain to ensure the cam is
in the correct position to the mark you made on the flywheel.
Cam Chain Tensioner.
5. Release the spring tension on the cam chain adjuster by removing the screw
cap and turning the adjuster inside using a small flat blade screwdriver
clockwise until it stops. This will remove all tension from the adjuster.
6.
Insert the adjuster and tighten the 2 mount screws while holding the 0 tension
on the adjuster.(Make sure gasket is in place.)
7. Turn the adjuster
back to full tension (rotate counter-clockwise, will rotate on its own) and
reinstall the cap screw.
Caution: Failure to release
the tension on the Cam Chain Adjuster during reassembly will damage the cam
chain beyond use. (The cases must be split to replace the cam chain.)
Adjusting the Valves.
1. Adjust the valve tappets using a feeler gauge to a clearance of :
Intake- .002- .004 � Exhaust .003-.006�
Note: Printer paper happens to be 0.003� :)
Note: Valves must be adjusted on a COLD engine.
Note: Adjust valves with engine at at TDC.
2.Loosen the 9mm valve tappet lock
nut and turn the tappet out several turns
3.Sandwich your feeler gauge between the bottom of the tappet (adjuster screw)
and the top of the valve
Note: Feeler gauges are thin pieces of metal which are a predetermined thickness.
4.Tighten
the tappet while moving the feeler gauge back and forth until you can feel
a slight drag on the feeler.
5.Tighten the lock nut with the feeler in place.
6.Ensure the gap is still within proper range by sliding the feeler back and
forth again.
7.Repeat step 2 - 6 for remaining valve.
E. Final Assembly and Inspection.
1. Rotate the assy several times by turning the flywheel then recheck the TDC-Mark
to Cam alignment.
2. Reinstall all remaining assemblies
in the reverse direction of disassembly.
3. Check operation of motor. ( Does
it start and idle?)
4. Check jetting and set as required by intake, exhaust and cam use.
This article has been downloaded 9,187 times
10 comments about this article:
A picture guide showing the steps to properly cleaning a gummed up DENkI (or equivalent) carburettor with carb spray.
Please see attached picture. Before starting, drain the fuel from both the gas tank and the float bowl.
1. Remove the carb from the engine by loosening the clamp on the intake inlet manifold. Flip carb over and take off the 4 screws holding the float bowl on.
2. Remove the float pin, push it through using a needle or other like tool.
3. Using a flat-blade screwdriver, remove both of the jets circled. Spray carb cleaner through the jets and passages that are circled. The spray should dissolve and remove any blockages caused by old gasoline.
4. Look through both jets. You should see light coming from the end of each one.
For carbs that are gummed up hard we use compressed air @ 120psi to clean the passages. In some cases using compressed air can actually lodge debris in harder than before, so please be aware of the risk before doing so.
Don't worry if a little gas spills out of the carb when you flip it over to get to the float bowl.
This article has been downloaded 9,187 times
14 comments about this article:
Diagram of the vacuum lines on the Yerf-Dog GX150 HOWHIT
The GY6 CVT transmission is composed of several key components: variator, roller weights, clutch, and the contra spring. There are also clutch engagement springs & different drive belts but that wont be covered here just yet.
Roller Weights – Changing out the rollers is undoubtedly the best bang-for-the-buck upgrade there is for your buggy. Roller weights provide the up shifting forces for the CVT transmission by flinging outwards within the variator in varying stages of engine RPM. Roller weight tuning is a matter of preference and riding terrain. A lighter weight will fling outward slower than a heavier weight, slowing the up shift process. The stock 14.5g weights are rather heavy and up shift very fast in the RPM cycle, resulting in hindered acceleration and low-end grunt. These are our notes regarding tuning and roller weights.
9 gram rollers - Unbeatable low-end grunt. However, this light weight will reduce top speed by 2-3 mph, and also kills acceleration.
Best for hill climbing, mud, sand, water and other loose terrain.
10 gram rollers - Great for overall performance. Spins most stock tires from a standstill with other supporting CVT mods. Good sustainable low-end power and optimal acceleration on hard-packed terrain. Does not reduce top-speed.
Best for pavement racing.
12 gram rollers - Reduced wheel spin at takeoff relative to 10 gram rollers, and smooths out acceleration. Terrible low-end torque when compared to 9 and 10 gram weights. Otherwise they function the same as 10 gram weights.
Best for loose terrain racing.
I recommend trying different roller weights to see what you like best. We carry 8 - 13 gram roller weights in the BD Online Store.
1500RPM "Power" Spring - The power spring provides the down shifting forces in a CVT transmission by working against the roller weights. CVT tuning is all about balancing the roller weights with a proper contra spring. The 1500RPM spring increases the tension on the belt and rollers. This delays the transmission from up shifting too soon and also reduces belt slippage. The 1500RPM spring itself increases and smooths out acceleration, low-end grunt, and maximizes back shift. "back shift" is the delay time it takes the transmission to down shift when engine RPMs drop. This is best visualized when thinking about coming in and out of a tight turn. Slowing for the turn the RPMs drop, you then clear the turn and apply full throttle. This is where back shift plays in -- you want the transmission to down shift to the proper lower gearing ratio as soon as possible through the turn so the CVT won't be stuck in an up shifted state when throttle is reapplied coming out of the turn.
The 1500RPM spring can be found in the BD Online Store.
High Stall Clutch - High-stall clutches engage at higher engine RPM, with more force than the standard clutch. This helps keep the small 150cc engine nearer to its power band during demanding situations where the power train is loaded to the point of clutch slippage. These situations can be during steep hill climbing, towing, or when pushing the front end up over large obstacles. High engagement clutches provide better launch from a standstill as well.
115mm Teflon Variator – The teflon variator are 12mm larger diameter than the stock unit. Stock is 103mm. The Teflon coated ramp plate the ensures smooth operation and increased roller weight life. The 115mm and variators are designed with steeper roller ramp angles for an improved acceleration curve. The revised roller ramp angles delay the CVT up shifting process until a specific RPM is reached, which I believe to be around 5500RPM. This keeps you well within good power range even at low speeds, and optimizes acceleration RPM when flooring it.
Transmission summary
If you are looking for-- LOW END GRUNT and don't mind a slight decrease in top speed you will want to take a look at this setup:
9g Rollers, High Stall Clutch, 115mm variator, 1500RPM Spring
For best OVERALL POWER OR TOP SPEED you will want this transmission setup:
10g OR 12g Rollers, High Stall Clutch, 115mm Variator, 1500RPM Spring
This article has been downloaded 9,187 times
4 comments about this article:
An explanation of how the GY6 150cc external reverse gearbox works.
The external reverse gearbox setup found on most 150cc GY6 buggies (and the buggy depot reverse kit) is actually a rather simple piece of machinery compared to most other gearbox designs. The brands of 150cc buggies that have this style of gearbox include but aren't limited to: Dazon, Blade, Carter Bros, Twister, SunL, Awesome Buggies, and several more. Here we will run through the basics of reverse operation. It is best if you are reading through this article while disassembling a gearbox real-time.
Important things to note:
- There is no neutral in this style of gearbox.
- The default mode of operation is FORWARD.
- Forward is 1:1 ratio.
First, lets go over the components of reverse. The major parts are the: shifter handle, reverse cable, output shaft, and gearbox. The handle is connected to the gearbox via the reverse cable.
The reverse cable is connected inside the gearbox to a yoke which is responsible for pulling an internal planetary gearset into REVERSE. A large spring is also held on this yoke to return the gear set into FORWARD position when tension on the cable is released. The gearbox receives power from and physically rests on the transmission output shaft, which turns due to the workings within the engine and transmission.
-Gearbox Internals-
Going into the gearbox, here are the major components:
1. Ring gear (The ring gear is the gearbox half that the external 16 tooth drive sprocket bolts to)
2. 3x Planet Gears & Carrier
3. Sun Gear (Output Shaft Gear)
4. Shifting Yoke
5. A few spacers and a bunch of grease
Now that you have a basic understanding of the internal and external parts, lets get into how the gearbox transmits power.
It all starts with the transmission output shaft, which sticks out of the final transmission case. When you press the "GO" pedal, this shaft turns clockwise. The output shaft enters the gearbox and meshes with a gear unit, which we will call the "Sun" gear. This sun gear rests in the center of the gearbox and meshes with both the planetary gears and a set of "dogs" (gear teeth) on the planetary gear carrier. This is the critical step. The difference here between being in FORWARD and being in REVERSE is simply a matter of whether or not these "dogs" are meshed with the output shaft. When the dogs are disengaged from the output shaft gear, the planetary gears will "lock up" and the entire unit (all components from the output shaft to the ring gear) rotates in FORWARD mode. When the gearbox is shifted into REVERSE mode, the carrier teeth engage and allow the planetary gears to spin - causing the ring gear to rotate in the opposite direction. When this happens, the inside of the gearbox looks very similar to this:
You should now be able to see why it is called a Planetary Gear System
This article has been downloaded 9,187 times
10 comments about this article:
Having a hard time finding where you're loosing spark? Look here for a detailed explanation of the entire Yerf Dog GX150 GY6 150cc ignition system.
To accurately diagnose your ignition system, you will need to do each of these steps in sequence. Start with step 1 and work through this guide completely.
This guide was originally written for the Yerf-Dog GX150, but has been re-written to cover almost any of the 150cc buggies, scooters, or ATV's with the standard "AC" CDI setup.
-----------
The 150cc GY6 ignition system is fairly easy to troubleshoot in the case of malfunction. There are 4 major components that work together to produce spark, if any of these is defective, spark will be lost. What we will be doing here is troubleshooting these ignition parts.
Ignition energy travels along the following path starting at the stator:
--1. Stator (6th winding and trigger pickup module)
--2. CDI unit
--3. Ignition coil
--4. Spark plug
First, bypassing your switches
A very common cause of no spark is a defective ignition or kill switch. Before beginning to troubleshoot ignition problems, it is best to bypass the switches. Some GY6 vehicles like the Yerf Dog GX150 have only one switch, but most others have two. The bypass process is the same.
Bypassing the switches
1. Reference this pinout diagram.
2. Create a jumper wire from pin #4 directly to a good grounding spot on the engine.
2. Remove the #5 wire from the CDI plug at the harness. This can be done with a sharp narrow tool like an ice pick or stiff paper clip. Looking from the front of the plug, you will see small metal tabs on each pin which secure them to the plug. Push the tab down and the pin will release. Be careful not to break the plug or pin.
Stator (Ignition winding and trigger pickup module)
Ignition winding: Depending on your stator type, you have either 6, 8, or 11 windings. Of these windings, one is dedicated to supplying the CDI with ignition power. This winding is usually wrapped in white cloth material and sealed over with clear epoxy.
Trigger pickup: A simple type of crankshaft position sensor. Sends a signal to the CDI to let it know when to send fire to the plug.
Troubleshooting the Stator:
1. Set your multimeter to read in VOLTS "AC".
2. Locate and disconnect the Black/Red and Blue/Yellow wires coming from the stator, where they plug into the main engine harness. (These are both bullet-style connectors)
3. While cranking the engine, use a multimeter to check for voltage coming from the Red/Black (CDI power wire) and the Blue/Yellow (trigger wire) coming from stator. Place the black lead of multimeter on a metal surface of the engine while using the red lead on the tips of the wires.
4. There should be between 20vAC ~ 100vAC coming from the CDI power wire (Black/Red), although much lower voltages will still be able to produce spark.
5. There should be at least 0.05vAC coming from the trigger wire (Blue/Yellow).
6. Write the voltages down and continue to the next step.
Normal values:
Stator output: 20vAC minimum.
Trigger output: 0.05vAC minimum.
The CDI Unit
The CDI unit is powered by the AC current coming from the wrapped stator winding. This current is stored in a capacitor within the CDI unit. When a signal is received by the trigger pickup passing over the flywheel magnet, the CDI will discharge the stored energy into the wires leading to the ignition coil.
Troubleshooting the CDI:
1. Ensure your multimeter is set to read in VOLTS "AC".
2. Just like before: while cranking the engine, use a multimeter to check for voltage at the two primary wires of the ignition coil. Connect your back multimeter lead to the black ground wire at the coil, and with the red lead to the lighter color wire (usually blue or purple, but it varies). At this step we are checking to see exactly what the CDI is outputting. Write the voltages down and continue to the next step.
Normal values:
CDI output: Can be 5% to 30% less than the output from the stator. The minimum we have seen working is around 18vAC.
The Ignition Coil
The function of the ignition coil is to multiply the voltage of the power supplied from the CDI, and to send the multiplied power to the spark plug.
Troubleshooting the Ignition Coil:
Check for 0.1 ohm ~ 1.0 ohm across the two primary coil terminals. This isn't exactly definitive, as we have seen working coils with 0.0ohms resistance. The best way to tell if the coil is bad is to perform steps the steps above. If there is still no spark, the coil is likely bad.
The Spark Plug
The plug is very rarely the cause of no spark on the GY6. If the plug is fouled or cracked it may not spark. Ensure that the spark plug is gapped properly.
The feeling of "bogging down" when throttle is applied is usually caused by one (or more) of three things. Running rich, running lean, or a weak spark. Look inside for an explanation.
Bogging down is usually caused by one (or more) of three things. Running rich, running lean, or a weak spark.
I'll start off with a very brief explanation of what Air/Fuel mixture is. The job of a carburettor is to atomize liquid fuel by injecting it into a flowing stream of air. The mixture of this air and fuel must be rather precise in order to combust within the cylinder. If there is much air, or too much fuel being delivered you will experience power loss and/or bogging down. With that said.. lets get down to the troubleshooting:
Most common cause: Running rich
Running rich (too much fuel in the air/fuel mix) could be caused by several things. The most common cause is a failing automatic choke unit. The choke on the GX150 carburettor is actually an enrichening circuit and in reality does not choke off any airflow at all. The auto-choke is ON in it's natural state. A failing auto-choke remains in the ON position at all times, thus it is characterized by the buggy running fine when cold, and hardly running at all when warm.
Running Lean
You may be running lean (too much air in the A/F mixture) if you are: 1. Having a hard time getting the engine started, 2. Once started the throttle is very tricky, too much throttle and the engine dies, and/or 3. Engine bogs and will not go beyond a certain RPM. This is commonly caused by a deteriorated intake inlet manifold. This inlet manifold can be found connecting the carburettor to the intake side of the engine. This little elbow-shaped inlet can form dry-rotting cracks, thus becoming a major vacuum leak. Please note: when replacing the intake inlet manifold, do NOT over tighten the nuts when securing it to the cylinder head.
Weak Spark
If the Air/Fuel mixture getting to your engine seems fine, then you may be looking at a weak spark. Ignition troubleshooting will be covered in detail on another page. The basic rundown is this: Stator/trigger wire -> CDI -> Ignition Coil -> Spark plug. It is best to check the resistance of the parts in question. Check the Yerf Dog GX150 Service Manual to find out the correct resistance values.
3. With the cover now off, you can see the variator, driven pulley, and belt. Locate the large nut (19mm) holding the variator assembly on the crankshaft. The minimal force needed to remove this nut is around 40ft/lbs. If an air impact wrench is not available, have a partner hold the variator cooling-fin plate steady with a strap wrench while loosening the nut.
Please do not hold the cooling plate in place by jamming items through the fins; this will result in damage to the cooling plate.
4. Remove variator as one unit by pulling from behind. Remove belt.
5. Place variator face down and insert your choice of roller weights. Make sure the three red spacers attached to the backing plate do not fall out.
6. Continue further to install the power spring.
7. Remove 19mm nut from clutch bell housing using the same method as the variator nut.
8. Remove bell housing and slide out the clutch & rear pulley assembly.
Please note: The large spring inside of the pulley is called the face buster spring, and for a good reason. Please be careful when removing the nut, as the clutch may be launched into the air if it is not properly restrained.
9. Secure they pulley and carefully loosen the large nut holding the pulley together. A large adjustable wrench can be used to pry the nut off while the clutch is held in place using a bench vice.
Note: It is best to just use the wrench to loosen the nut, then with the unit face-up on the floor use one knee and one hand to keep the spring compressed. Use your free hand to remove the nut, then carefully release pressure on the clutch.
10. Swap the old ring guide to the new spring and reassemble pulley.
11. Assemble in the reverse order of disassembly. Make sure to tighten the variator and bell housing nuts to 40ft/lbs.
12. Be sure to keep the variator tight while replacing the belt to ensure none turn sideways.
If your buggy seems very sluggish after installation, check the roller weights again. It is common for the rollers to turn sideways when installing the belt if pressure is not kept on the variator. This causes the transmission to start off in high gear. Disassemble and position roller weights correctly.
Beware of cracks developing in the area shown in the picture. Dirt particles getting sucked into the engine through intake leaks can lead to worn piston rings pretty quick.
If your airbox seal is cracking: First clean up the area from any dirt or dust. Grab a tube of epoxy and lay an even bead where the intake tube meets the airbox. Take your finger and smooth out the bead to reseal and reinforce the connection.
Let it dry and your ready to ride.
This article has been downloaded 9,187 times
2 comments about this article:
Want to replace your damaged spindles but don't know what generation you have? A picture and brief explanation inside.
The Yerf-Dog GX150 buggies were subject to several front suspension design changes while the buggies were in production. Not all generations of spindle and A-Arms work together. See below for info on how to distinguish which generation you have.
First Generation & Second Generation
The first and second generation Yerf-Dog GX150 spindles are identified by un-equal length A-Arms. The upper A-Arms are shorter than the lower arms. If your upper A-Arms are shorter than the lowers, our BDX 1st & 2nd Generation Heavy Duty spindle will fit.
Third Generation
3rd generation spindles are identified by equal length A-Arms. If all four of your A-Arms are the same length, our BDX 3rd Generation Heavy Duty Spindle will fit.
This article has been downloaded 9,187 times
2 comments about this article:
Ever wondered how the GY6 stator works? Click here for a short writeup on its inner workings.
The stock 6-pole stator is actually a very simple device. There are 6 windings total. 5 of these windings are wired together in series and are responsible for charging your battery and supplying power to your headlights & auto-choke. Positive voltage flows from the stator through the the yellow and white wires. The black wire is ground back to the stator. It must be noted that these three wires are completely isolated from the ignition system. You can unplug the 3-prong stator wires harness and the engine will still fire up just fine.
The 6th winding wrapped up in white layering seems to be dedicated to supplying the CDI with AC power. The blue/white wire leading to the black magnetic pickup is called the trigger wire. This wire is responsible for telling the CDI when to send power to the ignition coil, firing the spark plug.
Shown in this article's picture is a 8-pole stator. The 6 and 8 pole stators are similar in function, the key difference being that the 8 pole stator as 2 additional poles dedicated to charging.
-