I put a cobra megaphone on my three wheeler yesterday. Well, if the wheeler is idling and I give it a shot of gas (out of gear of course), when the rpm's go back down, it will backfire and a blue flame shoots out the back of the wheeler. Today I drove it and when I gave it a shot of gas while driving, it made the backfiring noise when the rpm's were going back down, but I didn't get to see if it was shooting the flame out the back this time. I was just wondering if there is anything I can do to stop the backfiring because it gets really really annoying after it happens a few times. Thanks for any suggestions.

 

Did you rejet the carb. It will need a bigger main jets and mover the needle. Here is a tip, look at your spark plug, if it looks white richen the carb. Your ideal plug will look a mid brown like a paper bag. And if you jet to rich it will be to dark. Good luck.

 

If you experience backfiring during ACCELERATION you may be leaning out or running on stale gas but if it backfires when you let go of the throttle then you have exhaust system leak. Check and replace exhaust system gaskets.

 

sorry if my other post was unclear. it backfires during DECELERATION. I checked the exhaust, it is leaking around the headpipe a tiny bit. I was also told it will always backfire because it is basically a straight pipe and I'm wondering if this is so. I checked my plug yesterday just to see if it was burning lean and my plug was a tan color. Once again, thanks for the help.

 

Sign of running to lean> Run your main jet up a few sizes and I adjusted my air/fuel screw to get rid of the decceleraton backfire. Go 1/4 turns till it's gome.

 

If it is backfirig on decel.. and you have a small leak in the pipe.. that's where the problem is coming...

the leak is alowing oxygen to enter into the hot exhaust pipe and exploding the mixture (which is richer and more unburned fuel when you decel)

fix the exhaust leak first. then do adjustments to the carb as stated above.