I went and looked at a bike with a friend last night and while it was running at idle there was a light backfire. The bike is an 82 CB650. Undoubtedly, I'll end up helping him fix it after he buys it so I better start doing my research now.
oem pipes? that one's prolly an exhaust leak(rusted) if it otherwise runs smoothly, i.e., no hang idle, good throttle response, easy starting, etc.
a crash truck driver's opinion: its too rich at idle, if has carbs: maybe jetting was changed from stock? or maybe a dirty air filter?
Has it been sitting with fuel in the carb bowls for a long time ( old gas ? ) ? The modern gas is 10X worse than the older stuff for clogging the carb when left sitting .
The current owner claims he cleaned out the carbs within the last month or so. It starts right up and idles well, it just has a slight backfire while idling but the idle is smooth.
Could be the carbs are still lean from the popping. Then again, you take a compression test before buying... That popping could be a burnt valve pushing out the a/c or exhaust side.
Just to clarify, are we talking about a backfire or afterfire? Backfire comes BACK through the intake Afterfire come out the exhaust (although this is incorrectly but commonly called a backfire)
