accelerator pump

just cleaned the carb on my yz, accelerator pump was all gunked up as expected. how much stroke should the actuating rod have? seems like 1/16th of an inch or less. it runs fine with no hesitation.

btw, the 51t sprocket has some extra pep on dry pavement, spins the wheel easily on the cinders. can't wait to get it in the dirt!

That 1/16 of an inch rod stroke sounds about right. That's what I noticed on my 426. Evidently, when that center rod is pushed down, the large diameter neoprene diaphram supplies the volume of gas.

What year bike is it? The '98 and '99 bikes have a different carb design which exposes the push rod to the elements. It's normal for the accel pump to get 'gunked up'. Some use grease/electrical tape to form a boot to protect the rod and reduce the build up.

Nice tip blbainb, thanks.

it's a 1999 and has the boot over the actuating rod. the grease idea sounds real good. i did notice however that the brass guide pressed into the carb body has a split in it to compensate for the press fit. this split probably allows more dirt into the pump than the loose fitting boot.

Do you think to much movement of the accelerator pump rod would cause a hesitation? I've gone way up on my pilot jet (50) and I still have a hesitation. I'm thinking i may be from the accelator pump pushing too much fuel. Is this possible?



Try a change of needle clip. Probably to a richer clip position. What is the needle code and clip position now?

James Dean,

Its stock all the way. I think 4th clip?


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