loss of power / backfire

[1980andy1100]

Hey fellows, its been a while, which means I've had a couple good riding seasons, but the bike has been acting up oddly lately.

I have ridden it a couple successful times this year. My last was a few weeks ago when out of the blue I started feeling a power loss, which kinda seemed to come and go as I rode. Eventually it started backfiring on me and was really hard to keep running. I ended up making it home after it started backfiring about 15 miles.... It was incredibly loud almost like a shotgun and the guy I was riding with said at times I was shooting 6" flames out of the tail pipes.

I pulled the plugs... I believe it was cylinders 1 and 3 were very black, however all the plugs are in good shape. After simply cleaning them it seemed to ride fine again. I was then out of town for a couple weeks. It was real rough starting yesterday and I had to keep the choke on a lot longer then normal. I didn't actually ride it because I am pretty sure it will still do the same crap. I believe I am having an issue with the ignition, possibly timing, however I am not sure what to start with.

Any ideas?

Thanks
Andy

[DGXSER]

The most common thing I have read of is the pick up coil wires. Look in the tech tips. ITs the first thing I thought of when reading your description of the problem.

[scalded dog]

...pic-up coils, also, how long has it been since you cleaned the carbs?. Later 'Dog

[dbeardslee]

How long has the gas been in the tank? I'd try some seafoam before I did anything, as the problem seems to be associated with the bike sitting. If the gas has been in there a long time you might try draining the tank and refilling with fresh fuel. If you suspect your pickup coils you can test them easily with a multitester, but I'd check the dumb stuff first.