It was too good to be true.

[tcoop]

The 81 SH that we traded the CB450SC for has a problem with the first gear (which I knew about when we traded). Now I find the tach and lights go out then back on while riding the bike continues to run strong. It is intermitted, goes out for a few minutes then comes back on as if it is shorted out somewhere.

I'm thinking that the stator may be going out or a short somewhere. I already checked the white wires coming out to the stator; the connector behind the fuse box was not melted. It was dirty so I clean it and put dielectric grease on it (I went ahead and did this to all the connections behind there) it still did the same thing.

We did put a different exhaust on the bike (the one off my 78E) not a perfect fit but good enough to pass inspection. I will look to see if any wires are hanging down that might have been melted by it.

I don't want to ride it too far from home (don't want to risk being stranded somewhere) until I find the issue here.

I do have a stator off the 78E that I can use (it has hole in the #2 piston)

Sorry for the ramble but sometimes it helps to write down the issues to figure out how to fix it. Any insight you might have would be appreciated.

[DGXSER]

First instinct is the old tried and true connector behind the fuse box. That connector could go loose and the bike still run off the battery then the connector reconnects and all looks good again.

Other place to look is the fuse box. if it is the original fuses, it could easily be vibrating a fuse loose and back in on you.

[tcoop]

It does have the original fuse box. I do plan on replacing that as soon as I can. Will the tach go dead from a bad fuse? I thought it took its pulses directly from the white wires.

[DGXSER]

I do not have a wiring diagram in front of me, you could be right on that one.

[bikerphil]

No fuse on the ALT wires, just gotta make sure there are no breaks/corrosion at the fuse box area connector. Check the connections at the voltage regulator too and there is a connector in the headlight bucket which is the least likely to corrode.

[3Phase]

It does have the original fuse box. I do plan on replacing that as soon as I can. Will the tach go dead from a bad fuse? I thought it took its pulses directly from the white wires.

'Coop, the tachometer should get its power from the Brown wire that comes from the 20 amp Signal fuse so, yes, the tach will go dead from a bad fuse. Also check for a bad ground on the Black wire from the tach connector or a burned/loose alternator connector behind the fuse box.

The White wire from the alternator provides the frequency pulses for the electronics that operate the motor and needle in the tachometer but no power.

[tcoop]

I guess that I need to break down and clean every electrical connection on the bike. The ones I did take apart to clean hadspider webs and corrosion in them. If that does not take care of the problem, swapping the stator only takes about a half hour.

[DGXSER]

Yep, from what you described, you need to just settle in wiht a six pack and some de-oxit or similar, some emery paper, some small files and just clean, clean, and clean every connector on the bike. Otherwise you are just waiting for the next gremlin to come up on the ones you ignored. I'd get to the fuse box sooner than later as well.

[crazy steve]

The tach and lights are different circuits if the wiring is unaltered, so I doubt if it's a fuse. I'd look at grounds; a bad ground can take out multiple items, even if they're on separate circuits...

[tcoop]

Don't know why I didn't think about the grounds. I'll have to add those to my list. Thanks

[CatatonicBug]

Also check the field coil. When the engine is running, the next time the tach drops off, immediately check for magnetism in the alt. cover. My favorite trick is to drop a razor blade against it. If the razor blade sicks and stands out straight from the alt, the field coil is good. Otherwise, that's another thing to check.

[greatnw]

Ground cleaning time agreed! The one that did the most for me was the rectifier to frame ground "under" the forward bolt that holds it on. Cleaned the corrosion and a lot of little things got better. I heartily agree on the three plug connector behind the fusebox and the fusebox in general.
I actually had a bad ground to the turn signals inside the turn signal socket that took a little time and patience to find.
Keep after it, you'll get it!