77d electrical problem, hand of god

[jgimar]

I have a problem but I'll be damned if I can find it. Just recently my bike started acting up. I'll be riding along and it like the hand of god reaches down and unhooks the positive lead to the battery and my bikes just drops dead. I'll check for power and no lights come on. I'll let it sit for a bit and sooner or later power will come back up and this little game will start all over again. sometimes it cuts out after only a few blocks, other times it may run for a day or two before it acts up. Always the same thing, cranks up fine, runs great while it's running, then out of the blue it dies, no electrical. I have looked at every connection I can possibly find and all wiring. Anybody ever have this problem??? What am I missing????

 

[gggGary]

Check/replace the ground strap, replace the fuse, overhaul the iggy switch?

 

[retiredgentleman]

+1 to what Gary said.

You're having the classic electrical fault that occurs with old bikes. Its imposible to pick out one connection and say that's the problem. Its just a process of elimination.

Start at the battery..............remove both large cables and clean the connections, remove any green stuff and make sure all connections are bright and shiney. Next inspect the fuse holder and the fuse itself, same for the ignition switch and the kill switch. As Gary said, you can take the ign switch apart and clean up the copper contacts. The kill switch may be oxidized badly or it may just be falling apart. All bullet connectors are suspect too.

All old bikes need this work, especially if they have set unused for long periods.

You also want to get familiar with using a VOM, to measure the battery voltage and the charging voltage at low and high rpm. A worn out battery or a charging system that does not reach 14 volts, will eventually cause the bike to die on the road.

For testing , you can use a length of insulated copper wire to bypass some of the items mentioned above. As an example you could run a temporary wire from the battery positive all the way to the ignition coil, and use a simple toggle switch to control power on and off.

 

[jgimar]

Check/replace the ground strap, replace the fuse, overhaul the iggy switch?

thanks for the help. when it first started i replaced the battery. i think the only strap i've run across that is grounded to the frame is the negative cable to the battery. i have yet to find a fuse or a fuse box on this bike.

 

[weekendrider]

The single fuse should have been under the right side cover.

 

[gggGary]

Yes negative cable battery to frame is the "strap", often corroded internally or at the frame bolt. Fuse should be under RH side cover, there is a red lead covered with white braid off the main battery wire at the solenoid, it should be plugged into the red lead of the single fuse on a 77.

 

[jgimar]

Yes negative cable battery to frame is the "strap", often corroded internally or at the frame bolt. Fuse should be under RH side cover, there is a red lead covered with white braid off the main battery wire at the solenoid, it should be plugged into the red lead of the single fuse on a 77.

ok. i'll change out the cable. i'm sure it hasn't been touched since 77. also i've been under the side covers many times and i haven't come across anything that looks like a fuse. just the regulators and solenoids but i'll look again and dig deeper. thanks again.

 

[gggGary]

Here's how Yo-mama meant it to be.

 

[jgimar]

Here's how Yo-mama meant it to be.

View attachment 41936

this will be interesting. can't say i've ever seen that under there. i'll let ya know

 

[jgimar]

+1 to what Gary said.
You're having the classic electrical fault that occurs with old bikes. Its imposible to pick out one connection and say that's the problem. Its just a process of elimination.

Start at the battery..............remove both large cables and clean the connections, remove any green stuff and make sure all connections are bright and shiney. Next inspect the fuse holder and the fuse itself, same for the ignition switch and the kill switch. As Gary said, you can take the ign switch apart and clean up the copper contacts. The kill switch may be oxidized badly or it may just be falling apart. All bullet connectors are suspect too.

All old bikes need this work, especially if they have set unused for long periods.

You also want to get familiar with using a VOM, to measure the battery voltage and the charging voltage at low and high rpm. A worn out battery or a charging system that does not reach 14 volts, will eventually cause the bike to die on the road.

For testing , you can use a length of insulated copper wire to bypass some of the items mentioned above. As an example you could run a temporary wire from the battery positive all the way to the ignition coil, and use a simple toggle switch to control power on and off.

thanks, i'll let ya know what i find out.

 

[XSLeo]

Here's kinda what the fuse holder looks like out of the bike. Your wires may be red. It holds the fuse and a spare.
Leo

 

[XSLeo]

Some of us recommend starting at one end of the bike and working your way to the other, unhooking, cleaning, inspecting, tightening, greasing, every connection in the wiring harness. Even before you first attempt to start the bike. This can eliminate a lot of electrical issues before they become issues.
Leo

 

[5twins]

Here's a close-up. The holder originally had a rubber sheath around it that slipped on a small tab on the frame .....

 

[jgimar]

Here's how Yo-mama meant it to be.

View attachment 41936

problem! here's what it looks like under my cover. no fuse located.

 

[jgimar]

Here's kinda what the fuse holder looks like out of the bike. Your wires may be red. It holds the fuse and a spare.
Leo

leo,
thanks. here's what is under the right side cover on my bike. still can't find any fuse set-up.

 

[jgimar]

Here's a close-up. The holder originally had a rubber sheath around it that slipped on a small tab on the frame .....

this is what's under my rights side cover.

 

[gggGary]

I'd take a closer look at what this is all about?



probably some sort of "job built" fuse or circuit breaker.

 

[jgimar]

I'd take a closer look at what this is all about?

View attachment 41978

probably some sort of "job built" fuse or circuit breaker.

actually what you are referring to there is just a piece of plasctic tubing stuck over the ends of those two posts. just stuck on one and bent over to the other. nothing inside of it. it's been like that ever since i bought the bike 15 years ago. i think the intent was to insulate those posts so nothing would contact them.

 

[gggGary]

What is it that the posts are attached to? I'm still thinking it's a "home brew" fuse replacement. That's the wire that the factory fuse "used to be" attached to.

 

[jgimar]

What is it that the posts are attached to? I'm still thinking it's a "home brew" fuse replacement. That's the wire that the factory fuse "used to be" attached to.

i'm at work right now but when i get home i'll trace down the wires coming off those posts and let you know. i'll take a better pic in the daylight also. this has me curious cause without having another 77 parked next to it to compare, i always thought what i had was a stock set up, yet i have parts that look obviously different from some of the other pics.