problems with humidity?

[mr. brass]

I have been using the search feature now for 2 days and cant find anything so here I go.
Bike: 1977 gs750 (pretty much stock cept for exhaust and appearance)

Issue: Bike rides great on dry sunny days, no issues at all, actually runs its balls off. Now the kicker. About a week ago I took it out one evening and about a mile in under half throttle it just felt like it went to half power and sounded really strange. I turned the headlight off and it came back to full power. It has done this many times since. Usually only in the evening when its humid (maybe im just paranoid) Just last Sunday I started her up at about 11 am after a rainy weekend and it was still very humid. The minute I started it up it ran terrible the whole time. The bike sleeps outside, so water may be getting in. Now yesterday after work it was warm and dry, started her up and it ran great, same for this morning. Does this sound correct in assuming it could be humidity causing a short? Maybe bad coils? Any help would be appreciated. This is my first bike that requires tinkering instead of newer start, ride stop bikes and I feel like an idiot, haha.

[bonanzadave]

What I would do......

Go get 4 new NGK plug caps. Cut off the old, screw on the new. Do the old girl a favor and give her 4 new plugs too.

Check the static (not running, key on) voltage at the coils. Disconnect the + wire and measure the voltage to ground. If its less than 10-11 volts I would start cleaning electrical connectors and consider the coil relay mod.

[marvinsc]

I think Dave is onto something. I haven't had any issue with bikes but had a few old cars in the past that didn't like moisture at all. Almost always came down to Plug wires and/or distributor cap.

[mr. brass]

Just got her 4 new NGK plugs. Heres a really dumb question, where are the plug caps?

[marvinsc]

The cap is the part that snaps on to the plugs.

[mr. brass]

Thats what I figured. They're really buried in the plug wires, how do i cahnge them? Sorry for all the dumb questions. Im more a car guy, but I just love bikes so much I have to learn!

[marvinsc]

Like Dave said, You cut the old ones off flush. The new ones should screw right on.

[mr. brass]

so maybe im the idiot here. I cut the cap out of the plug wire boot then screw the new ones onto the plugs, like typical systems on cars go, correct? And how do I cut the cap out without harming the plug wire boot?

[mr. brass]

Im a complete moron, hahahaha. Thank you guys for your advice, I was thinking about that spark plug cap way, WAY too hard. Im going home to change the caps, do the relay mod, and wrap every connection in electrical tape.

[bonanzadave]

wrap every connection in electrical tape.

Not necessary. Get a can of spray electrical contact cleaner. Take apart and spray each and every connector on the bike. You can reassemble the connectors with dielectric grease. That should keep the moisture out.