Carb backfire / Glowing red pipes 82 fl

[Karp13]

The bike is backfireing thru the carb seems to be worst in mid rpms, but will back fire at idle and higher rpms. The pipes are turning RED HOT close to the exhaust port. One plug insulator is half white half black the other plug is dark, the electrodes are very clean. Changed gas. It would seem the bike is lean, so I disassembled the carb cleaned it completely and still have the same problem. And yes I checked for air leaks. The bike sat for about 3 years and the drag pipes that were on the bike rusted thru so the owner put on regular stock style mufflers. Jets are 72 idle 175 main. Stock Electronic ignition. Any ideas where to look next. It seems to be jetted for the drag pipes, so I would think it would be rich with stock mufflers.

Thanks for your help
Karp13

[HDMD88]

Originally Posted by Karp13

The bike is backfireing thru the carb seems to be worst in mid rpms, but will back fire at idle and higher rpms. The pipes are turning RED HOT close to the exhaust port. One plug insulator is half white half black the other plug is dark, the electrodes are very clean. Changed gas. It would seem the bike is lean, so I disassembled the carb cleaned it completely and still have the same problem. And yes I checked for air leaks. The bike sat for about 3 years and the drag pipes that were on the bike rusted thru so the owner put on regular stock style mufflers. Jets are 72 idle 175 main. Stock Electronic ignition. Any ideas where to look next. It seems to be jetted for the drag pipes, so I would think it would be rich with stock mufflers.

Thanks for your help
Karp13

Yes more back pressure the richer the carb gets. Check the timing or look for the ignition wire being pinched or frayed from installing the stock exhaust system down by the cam cover. The ele. Ign. box could be bad also having the timing retarded....check the VOES vac line too.

[Karp13]

Good call on the timing being retarded! It was way off. I set the timing with a timing light and now it is dead on (35 degree advance @ 2000rpm). The backfire is now in the exhaust, which I figured would happen with the jetting the way it is.

Now there is still one problem the pipes are still glowing. I thought this would go away when it is running rich?

Any ideas, this is my first experience with glowing pipes.

Thanks

[HDMD88]

Are you running down the road or just sitting still when they glow? Do you have a good seal on the pipe to head? if not get a good gasket in there and align the pipes so you get a good seal.

[Karp13]

It is sitting still in the shop and I am not feeling any exhaust leaks at the head. I will try it with a couple of fans blowing at it.