Honda GB400 TT backfiring.

[ryuvsken86]

My Honda GB400 TT is backfiring occasionally. I just got the bike a week ago and filled it up with straight 91 unleaded, and it was backfiring a little bit. I've put 98 in there this time and it backfires. I know it has something to do with the Air/fuel ratio, but was wondering how I would go about fixing the problem myself?

[AllanB]

Depends on your definition of backfire.

Is it is a snap crackle pop from the exhaust when you throttle off?

Is it a full-0n bang out of the carb?

Is it a bang when cruising along?


Won't need 98 octane in that motor. 91-95 will be fine.

Has it a stock muffler or aftermarket one - or rusted out stock one? When running can you feel gas coming out any of the pipe joins (usually header/muffler join?

What's the service record like? Air filter clean?

there could be a lot or not much going on.

I'd start with the muffler/exhaust - if it is leaking gas at a join then air will get in on deceleration and can ignite the unburnt fumes giving a nice pop. If the bike has a stock clean air injection system it is usual for a quietish pop pop pop on deceleration - if you have a rowdy muffler this will be more noticeable. Perfectly normal. My Ducati sounds glorious on deceleration - was unruly that way from the factory!