Posted by ls650v on June 15, 2003 at 04:28:01:
In Reply to: carbon buildup on vacuum piston posted by Richard fssnoc#(Ks) on June 14, 2003 at 20:19:27:
This gunk buildup on the vacuum piston also happens to me. I can go anywhere from 1000 miles to 3000 miles before I notice a mid-range flat spot. The buildup is on the vacuum piston and piston bore. The rest of the carburetor is always clean. I have been assuming that this buildup is caused by oil vapor and combustion blowby coming from the crankcase breather hose connection to the airbox. I have been meaning to disconnect the crankcase breather hose from the airbox, plug the resulting hole in the air box, and attach a crankcase breather filter to the hose. Just never seem to get around to it.