Motorcycle Repair: 1982 GL500 Silverwing Electrical problem/backfire, amp fuses, fuse holders

Question
Hi Chris,

I recently purchased a 1982 GL500 with a couple of problems.

1, the front headlight will not light up, or the rear signal lights. The horn does not work either. The running lights on the fairing DO work but do not blink as signals. Rumor has it that the "main" fuse in the box had had a wire laid straight across, instead of holding a fuse, and that the other fuse holders had a couple 20 amps instead of 10.

The bike does start and run (new battery) and I placed all new 10 amp fuses in it. None burned out. None of the electrical problems sorted themselves out, though. Is there a good place to start looking for this problem, a "likely suspect" where all of these systems could go?

2), the bike backfires out the right side when given gas, or when the gas is held steady. It does not seem to do this out the right side, however. Does this RULE OUT any problems (timing chain, for instance?) The air boots are a little cracked on the surface, but the cracks do not appear to penetrate the rubber. I have purchased a new set to be on the safe side. The bike is NOT spewing oil out the pipe either, which makes me suspect the rings are OK. My untrained ear may detect a bit of a rattle in the head when the backfire is going on. Does this point to anything?

I do have a manual around. I actually owned the 650 version of this bike, but quickly traded it it away as it needed repairs...

Answer
Hi Kawazacky.

Sounds like a few problems here.  I will address them one at a time.

1) For the lights, the issue is normally fuses for these things, but in your case, the fuses could have bad/corroded connections.  Also the wiring could have multiple shorts and/or bad connections.  For the signals you may need a new flasher relay.  If there is a test proceedure for it, then do that before you replace it to be sure.  Check that main fuse. If rumor was true, then a variety of electrical components could have problems because of excess power running through them from possible bad wiring.

2)  For the backfiring, you need to check and correct a few things;  valve gap, valve timing and ignition timing.

For the carbs, you need to replace those intake manifolds.  The cracks do indicate air leaks in the system.

Start with those and let me know what happens.

Good luck and ride safe.
FALCON