hi guys i have a drz 400sm and i recently got hold of a fcr 39 carb the slant one from a ccm 404 as i was so excited to fit it i put it straight on the bike and it run ok but if i snap the throttle back when the bike is at low rpm it nearly kills the engine. I'm guessing from reading up about them it could be the jetting but i believe the ccm has the same engine so is it that? also can anyone point me in the right direction to buy the jetting i need, I'm in the uk. my bike has standard head pipe small sm one and open race exhaust, sea level. any help is much appreciated guys thanks.