Cuts out when hot

[sthomag]

My 78 runs fine for a few minutes, then simply stops. It's definitely an electrical problem: not only does the ignition fail, but the starter doesn't respond either. The oil and neutral lights (and headlight) remain on, though. After a few minutes, it will run again, but soon quits again.

The first time it happened it was just like a big stumble: it cut out for an instant and then kept running. It has gotten progressively worse since then.

I've gone through the wiring and connectors, cleaning and checking. The tip-over switch looks fine, the kill switch looks clean as a whistle inside. I replaced the ignition module, which had no effect.

Any ideas? I'm thinking it might be the pickup coils -- but how would that affect the starter? Also, if one pickup went out, wouldn't the engine run on two cylinders?

Please, any ideas?

Steve Thompson

[CatatonicBug]

Someone just posted about a similar problem earlier. One suggestion was to check the ground strap at the rear of the transmission case, just below the airbox. Remove and clean the connections, and use some anti-sieze on both ends to improve the electrical connection. Also, what is the voltage coming off your battery at rest/while running?

[DGXSER]

Are you sure it is electrical related?

This sounds an awful lot like the carb bowls are getting filled slowly while it sits, then fuel can not run into them fast enough from kinked or plugged fuel lines or messed up petcocks, so the thing runs out of fuel and dies. Then while it sits the fuel trickles slowly in to refill the bowls. JAT

[CatatonicBug]

Are you sure it is electrical related?

Sounds like it to me too... If it was just fuel, the starter would still try to crank the engine.

...but the starter doesn't respond either.

[psycoreefer]

could be a lot of things...but I'm guessing its probably two different issues 1. the starter doesn't work when warm and 2.the bike stalls after running for some time.

#2 will be easier to diagnose if you fix #1

when you push the starter button after it quits do you hear the solenoid "click"? Check the ground as mentioned. Check with a meter or test light that the starter button is supplying power to the solenoid. In another thread someone suggested "tapping" on the outside of the starter with a soft hammer or hammer and block of wood while holding the start button down. If that works you probably need to rebuild\replace the starter.

[sthomag]

When the starter works, the ignition works, so I'm pretty sure the two are related. When the ignition cuts out, the starter doesn't work either. There are no clicks or anything else from the solenoid: it just flat doesn't work. It's obviously getting no power.

The ground strap sounds like a possibility. Any other ideas?

Steve Thompson

[psycoreefer]

basdfasafsafsafsaf

[3Phase]

Any other ideas?

Steve, it could be the ignition switch or the connector is bad. If you don't have a fairing the ignition switch connector is sealed up inside the headlight shell.

I rode ~120 miles one night with the power cutting in and out on the freeway. I do have a fairing so I could just reach down in front of the handlebars and move the connector around until it started working again. I temporarily soldered the wires together the next morning at the motel but that was not a fun ride.


Regards,

Scott

[mxmikie]

i had this problem was the ignition switch

[cywelchjr]

Or maybe the kill switch. IIRC the kill switch also disables the starter, which means that you can't use it to let you spin the engine without the ignition being in the circuit. I figure that has something to do with how the solenoid energizes the coils while it's engaged, so it it was opening up, it would both kill the ignition and stop the starter from working, and it would tend to get worse over time as well.

[sthomag]

I'm beginning to think the ignition switch is it. The ground strap looks clean, and the bike runs without it anyway.

I looked at the wiring scheme, and noticed that the switch closes two circuits, one of which powers the lights, etc., and the other of which powers both the starter solenoid and ignition. So if the ignition contacts go bad, the lights still work.

I'll let you guys know how it turns out.

Is there anywhere to get a new ignition switch?

[BigRed]

You might be able to take the ignition switch apart and try to clean it up. I've also got a Honda CX500, and lots of people have had to do that (I need to right now).

[DGXSER]

There was a recent thread with a great pictorial description of how to take the ignition switch apart. If you want a new one, Parts-n-more sells them for $15 unfortunately they have a minimum $35 order.

[yamtom]

conducting anti seize?

Hi CBug,

I didnt know that anti seize conducted electricity although, I am not dogging you, just would like a confirmation that thats not a typo.

[3Phase]

I didnt know that anti seize conducted electricity

Hi, Tom, not Cbug here but there are two different products:

The anti-seize used on spark plugs will conduct electricity or the spark plugs wouldn't fire. It usually has some copper in it. It also works great for large, single connections like battery terminals, grounds and other connections that carry a lot of current. Clean the connection and use just enough to make a light coat. Clean up any excess. If you use too much you can create a short circuit somewhere else because, being grease, the stuff can get everywhere you least expect or desire. Put a dab of some regular grease over the connection to seal it up; it's less expensive and usually not as messy.

Dielectric grease doesn't conduct electricity. It seals out dirt and moisture and is a clear silicon paste. Again, just use a light coat on the actual connections but add a little dab or two on the back to fill the gaps around the wires. If you use too much the connections will stay nice and clean but they may not work. It's easier to use than copper anti-seize because it can get all over the place too but it doesn't stain everything it touches and it can't cause a short circuit!


Regards,

Scott