Anybody out there still running with lid on with fmf exhaust and k&n filter? Mine seems to run so lean that if I put the lid on it runs much better.
Anybody out there still running with lid on with fmf exhaust and k&n filter? Mine seems to run so lean that if I put the lid on it runs much better.
Wow, 340 is BIG, it almost makes me wonder if you don't have a vacuum (air)leak somewhere. I really can't imagine that it would be that lean otherwise. 310 is Toomey territory & I don't think the FMF is the same beast. Start checking elsewhere man.
Could the carb be letting in some air when it is bolted up, is the little nipple on the oil intake on the carb.
#340 main is really big for a FMF without the airbox lid on.
What oil/fuel ratio do you mix to?
What other mods are you running?
What jet were you running in summer? I was running 310 in summer with lots more done to it with no lid. Tho spraying around outside is a good quick check, it cannot detect seal or case leak. Do a proper leakdown test, use soapy water and find leak. Thought someone else would have also responded.