I have a 1982 Suzuki RM250Z I've just restored. It starts and runs great, but craps out from 1/2 to WOT.
http://www.bikepics.com/pictures/947743/
http://www.youtube.com/watch?v=GbkZN2Md6xQ
It has the stock jetting and air box, no holes drilled. I ordered all new pilot jet, needle, needle jet, and 2 sizes of main jet smaller than the stock 290. That's the only thing I can think to do is to replace everything and try a couple sizes smaller main jet.
Moving the needle clip all the way lean doesn't solve the problem. I'm not crazy about running it with the air filter off, too dusty in my yard. But I've tried the other end of the spectrum by turning on choke once its warmed up and it gets worse. So it seems rich 1/2 to WOT.
Symptoms are that it sputters and does kind of a back-fire when you get up in the throttle past 1/2 way. I have some dents in the pipe and there may be a small hole on the seam, would this cause so much trouble?
It starts, idles and revs fine when not moving. Choke is working correctly. I got this bike in pieces though so I've never seen this carb run on a bike.
I read somewhere that a worn needle valve will cause the problem I'm having, so hoping new parts will fix it.
Any help would be appreciated, I haven't worked on 2-strokes for more than 20 years so I'm a little rusty but pretty solid under the rust.
Thanks,
Marc
