backfire?

ok...bought an 83 maxim 650 this sping...decided it rebuild it...rebuilt the carb s...starts fine , idles, also had the carbs synced....on to the problem...have a buddy with a 750 raiden...it is faster than hell....here is my problem..i dont have the power on start off...im going through fuel like crazy...but no leaks.. and at 45 mph..i get a backfire on the right side...i just cant get the power...oh btw this bike was a bone stock maxim when i got it...here it is now..

 

Sounds like a fuel/air mixture issue. A lean or rich mixture can cause a backfire. You should do a search of the forum for backfire - I recall reading quite a few really informative posts on the subject.

Start with the basics - carb synch then colortune.

Hope this helps.
Good luck.
Rob

 

When you had the carbs synched, did they use a YICS tool? Have you adjusted your pilot jets at all? What changes have you made to the intake/exhaust? Have you cleaned out the carbs thoroughly? I assume you replaced the float needle/seats. Did you reset the float heights? Sounds like a rich condition, or blocked carb passage. Give us as much info as possible, and we'll try to help you nail it down.

 

Depending on how old that exhaust is, it tells a story on it's own.
Can't see pipe 1 but 2 and 4 are very blue indicating a lean(hotter) mixture. Number three looks about right.

Not a great diagnosis method but pipe temp does give an indication how it is running.

If you haven't colourtuned then I would look at setting all the mixture screws to the same as number 3, assuming of course, that the pipes were not like that before your carby work.

Tail pipes look narrow and non standard. Any bafles in there or are they straight thru.

Also check for air leaks.. Common cause of backfires.

 

If it is backfiring out the exhaust then I would suspect a rich mixture. If throughthe carbs then a lean mixture. The best thing to do is a colortune. Also if your mixture is rich then oening the throttle slightly at speed would give an initial smoothness or surge of power. IF it is lean then slightly backing off woud do the same thing. Try this out and see what you find.