What are the possible causes of constant exaust backfire? I have rebuilt the carb 3 times and it is so spanking clean I don't belive that to be the problem. I changed the compliance fitting the last time I rebuilt the carb and I get a great smooth idle but a constant back fire from the front exaust. The bike is a 1988 fxst with a stock carb and milwaukee twins exaust. I really need to get this bike running again and can't afford to put more money into it and before I tear it down againI'd really like a clue as to what I'm looking for.

 

might sound stupid but check your plugs. If I leave my enrichner out too llong in the morning, I pop all the way out my driveway like Uncle Buck, then i pul the plugs and clean em off and Im all good.

 

I changed the plugs a few hundred miles ago but pulling a plug sure beats pulling the carb again. I'll give it a try. Thanks!

 

check for an exhaust leak and check your timing if you are sure your mixture ratio is right.

 

backfire causes
1) fouled plugs (most common)
2) bad spark plug
3) bad spark plug wires
4) bad coil
5) bad ignition module
6) dead battery combined with a pooched charging system
7) bad gas (water or just old)
8) engine timing
9) electrical wire short

 

Plug or wire as in earlier post....It has to be related somewhere.Maybe coil?

 

Oh My GAWD!!!!
My old hog runs good again!!!!!!!
Way too many thanks guys.
It was the plugs and I'm an old biker again!
Thank you
Thank you
Thank you

now I just gotta sober up so I can ride the machine again.

 

backfire causes
1) fouled plugs (most common)
2) bad spark plug
3) bad spark plug wires
4) bad coil
5) bad ignition module
6) dead battery combined with a pooched charging system
7) bad gas (water or just old)
8) engine timing
9) electrical wire short

 

Hi, this is the right exaust of my 2003 Electra with CV carburetor. I have a misfire only when I start the bike. Someone know why? How to fix? Any help will be appreciated

 

The ten year plus reply above your post is a good place to start..

backfire causes
1) fouled plugs (most common)
2) bad spark plug
3) bad spark plug wires
4) bad coil
5) bad ignition module
6) dead battery combined with a pooched charging system
7) bad gas (water or just old)
8) engine timing
9) electrical wire short

Griz