Well, I know people have posted things other than klx questions so I thought I would see what kind of response I may get here. So, I have an 87 kawasaki mojave 250 and I'm wondering how can I tell if the vacuum piston is moving up and down. This 4-wheeler was given to me about 6 years ago and I have been slowly restoring it. Not trying to get it in show room condition but just bring it back to life. The vacuum pistion moves freely with my hand and is in good conditon. When I start it up with just the carb in place the vacuum piston never moves up when the throttle is opened.

So, the question is what can I do to bench check the carb and get the vacuum piston to move? Maybe hook up a shop vac or something to simulate the sucksion of the motor.

 

If engine vacuum isn't raising the slide, then hooking up a shop vac won't matter. The vacuum slide diaphram is either not seated and sealed properly, or it has a tear or hole. Take the cap off the top of the carb and check out the diaphram. If it's torn, you can't just buy the diaphram, you have to get the whole slide.

The Mojave uses the same engine as the KLR250 (only with a backwards kickstarter) and the same Keihin CVK34 carb as the KLX250s and a lot of other bikes (only without the throttle position sensor). The vacuum slide is right around $100 new, but I'll bet you can find a whole used carb for cheaper than that.

 

Thanks, I'm almost postive the diaphram is in good shape and seated correctly. I'm going to look into this weekend. I found one on the internet by JP cycles for $44. Not sure how well that would be compared to OEM.

 

Well, I didn't have the vacuum piston seated correctly. I did some research on the internet and found that you can streach the diaphram a little bit to get it to seat right. I tried it and it worked great. This thing hauls *** now.