GY6 Tech Article Summary:
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.

Keywords:
GY6, 150cc, No Power, Bogging down, Choking Out

Loss Of Power Troubleshooting: Bogging Down
Written by Travis @ BD-ORB
This article has been viewed 3253 times.
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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.

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