Hi guys, I desperately need some help ! I've just bought a '90 KX 250, and I'm having lots of trouble with it. The main fault is that it takes ages to start, and then it won't idle at all unless I screw the idle adjuster all the way in. If I rev it then, it takes ages for the revs to drop back down, and usually cuts out again. Also, it's chucking out loads of smoke, and it seems to be misfiring at low revs. Above around 1/4 throttle, it seems fine.
I've cleaned the carb and filter, fitted a new plug, but things are no better. It's on a standard needle, I've tried 160 and 165 mains, 45,50 and 60 pilots, and the air screw everywhere, all to no improvement.
I was just cleaning the bike, and noticed a crack in the bottom of the crankcase around one of the bolt lugs. I can't tell how deep it is, but would an air leak here give the symptoms described ? If so, any ideas on an easy fix ?
Sorry for the long post, but I'm pretty new to the two stroke MX thing, just come across from years on the road.