The direction I usually recommend for buggies (scooters and ATV's as well) involves improving torque, acceleration, and responsiveness first (being careful not to reduce top speed), and going for power adders later. I'll explain:
There are generally two sides to GY6 performance improvements:
1. Power adders (Engine mods)
increase the power at the crankshaft, which is generally expensive and harder to install.
2. Power optimizers (CVT mods)
allow us to take advantage of the engine's power better, and are very effective at getting the machine physically moving quicker even if actual power at the crankshaft isn't changed. These mods are usually very affordable.
Best first GY6 "bang for your buck" upgrades
1. Uni Filter High Flow Intake Kit
The UNI Filter and Intake gets the top spot, because it is the single best upgrade to make sure that your engine lasts as long as possible. The performance benefits stand on their own, but when you see the damage caused by inadequate filters
, the first upgrade choice is clear.
You can get the UNI Filter Kit by itself, or as part of our STAGE 1 Engine Upgrade Package with more easy starter power adders.
2. Roller Weights
Roller weights go a very long way to increasing usable power. 10g is the best overall size and what I most commonly recommend. Allows for substantially better acceleration and climbing power. 12g is best for flat terrain (track, etc). 9g or 8g are good for times when you're going to tackle very hilly or technical terrain. They aren't heavy enough to fully expand the variator, so top speed will be reduced. They'll help you climb like a goat though.
It's a good idea to keep different sizes on hand. Rollers are easy to change out in about 20 minutes. So you can quickly swap in the set that is best for the type of riding you'll be doing at the next riding spot.
I've found that "tuning" the CVT like this keeps things interesting. And keeps my buddies wondering how I'm able to beat them at each different place (and terrain) that we ride.
3. CVT Power Spring
This is the giant spring behind the clutch. I almost always recommend the 1500rpm version (yellow). Take a look at my full article on How the CVT works
to get a really good visual explanation on how the rollers and the spring work together. BTW: Don't get the 2000rpm spring, unless you never plan do go above 25mph. Also, don't confuse this with the 3 springs in the clutch (see below).
Get the rollers and power spring together in our STAGE 1 Drivetrain Upgrade Package.
I recommend doing these three all at once. You'll notice the difference immediately on the first ride after installation.
Let me know if you want to know more
If you (or anyone reading) want to know more, come back and reply in this thread and I'll follow up with the next level of upgrades and the reasoning behind them.
What NOT to spend money on at first:
Clutch engagement springs:
I've found that it's best to leave them alone unless you have a specific reason to alter your engagement RPM. Sure, you'll get a boost out of the gate when going wide open. But personally for me, it's irritating constantly engaging and disengaging while riding normally at low speeds. Generally I'm happy with stock engagement.
Big Carburetor (28mm or greater):
This falls into the "Internet Bullsh*t" category. Too many keyboard racers will try to tell you to install a big carb right away. Don't do that. You'll just lose low-end power with very limited high-rpm gains. It is very true that a big carburetor will really wake up a BIG BORE engine. But not a stock engine. Stick with the stock 24mm.
The only exception is the 26mm Mikuni VM26-606, which is in my opinion is a very good (but not cost effective) upgrade even for an otherwise stock engine.