BACKFIRE ?

coachk

Active Member
When I'm shifting gears I get a backfire when I push in the clutch to upshift to the next gear. It does not happen on deceleration (downshifting).

When pulling in the clutch to upshift I am rolling back on the throttle so I guess technically I am decelerating, I guess. Would this scenario be more likely to be a leak somewhere in my exhaust. A buddy of mine said that backfires on decel, more than likely mean a tune issue.

Thoughts?

Thanks
 

bigdogtech01

Well-Known Member
When I'm shifting gears I get a backfire when I push in the clutch to upshift to the next gear. It does not happen on deceleration (downshifting).

When pulling in the clutch to upshift I am rolling back on the throttle so I guess technically I am decelerating, I guess. Would this scenario be more likely to be a leak somewhere in my exhaust. A buddy of mine said that backfires on decel, more than likely mean a tune issue.

Thoughts?

Thanks
Yes you very well could have a bad exhaust gasket. You can look around the gasket area of the cyl head and see if any black around the pipe or if the nuts are loose at the flange. New gaskets are only $10 for the pair...make sure you get the tapered style, not flat.
You may also have an intake leak at the manifold seals. You can test my running the motor at idle with it at operating temp...spray one cyl at a time with brake/parts cleaner to determine if you have an intake leak. You will want to spray the area on intake manifold where the seal is.
Also look for any missing rubber plugs on the carburetor nipples. If a rubber plug is missing or dry rotted, it can cause an intake leak as well.
The fuel air mixture screw can cause backfiring as well. But, normally this is something that progresses rather than an all the sudden thing (unless someone has turned it recently) The needle can wear out and can be replaced if needed for only $8. If you are not sure on checking these things, feel free to give me a call.
 
Top