I just bought an 85 250CR the other day, and it seems to be having some trouble keeping the correct fuel level in the carb (stock TM38). Idle rpm is all over the place, anywhere from 0 to about 4000 rpm, have to give it a bit of throttle every now and then to keep it going. My first thought was a leak somewhere between the carb and the cylinder so I inspected everything on the inlet side and it all looks fine. No cracks in the carb rubber, good seal between the rubber and reed holder, and same between the reed and the cage. Even though it all looked fine I added some liquid gasket to make sure there are no leaks. The problem remains though.. When the engine is running, the carb is spitting fuel all over the place through the evac hoses. When not running (vibrating) it all works fine. I lowered the float level a bit but to no avail, it spills just as much. So next thing on the list is to replace the needle valve and seat. But I can't find anywhere what size it's supposed to be. The parts manual just says "needle valve" and it's not listed in the carb specs either. Will a 1.5 or 1.8 do or does it need to be larger? I couldn't get the holding screw out so I don't know what's in there now but I suspect it may be too large, causing it to overfill whenever it opens. Other theories are welcome too, I seriously doubt it's supposed to spit like that though so fixing that would probably be a good start
try reposting this in the vintage/left kicker section and there will be some help for you...this in wrong section
