All 2st Carb Vent question

Last time I rode my 99 WR250 (just before snow, temp not that cold) I noticed it seemed to be smoking heavily. Even after running for a few miles. I also noticed what may be a hi speed detonation in the 3/4 throttle range while under acceleration. Clearly signs of a lean engine.

Although the symptoms sound like a crank seal, I found something yesterday and wanted to check it out. I noticed most of my carb vent hoses were pinched shut. Looks like I may have pinched them between a frame crossmember and the skid plate. Is it possible the carb vent hoses, if pinched, could cause a lean condition?

The top end is not recent but does not have that much time on it either. The engine has very strong comression and runs great.

Any thoughts?

Yes, that could cause a lean condition. Reason is that if the carb can't vent, then the in coming fuel can't displace the air in the bowl.

The smoke could have been oil being burned from the pipe due to the heat of the lean condition. If you do a lot of low speed trail riding there could have possible been a good build up of oil on the pipe walls that got burned off.

Fix your vents and try it again.

Thanks for the info Motorhead. I have fixed the vents and will give it another shot. I do appreciate your res[ponse!