80 shifter hard to start and bogging

Hey guys,

I bought a yz80 shifter a few years ago and I’m tinkering with it again. I can only get it to start with starter fluid, but once it’s running, it idles and responds fairly well. Sometimes after blipping the throttle the idle stays a few hundred rpm’s higher and slowly falls back down to steady. Outside the power band the kart is extremely sluggish but it pulls very hard once it’s in the power. I’m not a carb guy, just wondering where to begin. I only see 2 adjustment screws, one being a knob you can turn by hand with a jam nut behind it, and the other a small flathead screw that seems to go down to the bowl. The kart is also extremely hard to get going from a stop. I used to ride two strokes and drive manual on the regular but it seems off. I’m attaching a small video of the kart in neutral

Did you rebuild/service the carb or fuel pump?

Fuel pump and lines are new but I haven’t rebuilt the carb yet. I pulled the float bowl and it looked good but I guess a rebuild would be the next step. I just wanted to know if it could be some tuning before I went pulling it apart.


I’d be careful starting a 2-cycle on starter fluid because you are washing away any lubrication the engine had. Try choking it a bit.

Maybe check for a cracked, broken, or stuck reed valve.

Changed out the reeds already as well

A high idle after revving usually means it’s a bit lean on the idle circuit, or you have an air leak somewhere. Crank seals are a possible culprit when the engines have been laying up.

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