Won't stay running ...

[Anonymous]

I just FINALLY got my bike back on the road after missing all of last year's riding season due to the purchase and renos in our new house.

I have a 78 GS750e. I just had the carbs disassembled by a shop, dunked, cleaned and reinstalled on the bike. When we fired it up, it ran great all the way home (about 2 miles). When I went out for a good ride that evening, it ran DOWNHILL for about 2 mins and then just shut off. I had to push it home about a mile up hill and then I did some experimenting. At first if I fired it up, it would run forever at idle until I engaged the clutch cable. If I touched the clutch lever, it would stall instantly. After a while, I was able to ride it again for about 1-2 mins and then when I was riding along, it would just die. One other thing that was odd was when starting it, if I hit the starter button, it would turn over until I released the button, when I released it it would fire at that moment but not until I released it. Occasionally when I did this, it would backfire as it started.

Please help me. A friend sent the carbs out for me cause he couldn't fix'em himself and they were done by a reputable shop. It's probably something simple and I'll be riding again but I don't want to go back to my friend and thought you guys might be able to help.

Thanks for your thoughts or advice.

Pat
pattaylor@telus.net
1978 GS750e (totally stock)
Vancouver BC Canada

[KEITH KRAUSE]

Sounds like a ground or short in the clutch switch? It's only used to start the bike, but if touching it actually kills the bike then it needs to inspected. It could be something similar in the starter switch though. Both switches are connected at one point.

[gremlin]

change the fuel filter. probly junk in it, letting you "run" out of fuel.

[Anonymous]

Is there a fuel filter on it ? I'd like to put one on it but I don't see one anywhere. What's a good kind to put on GS750s ? The Petcock was removed and I'm thinking it might be that it's not allowing the fuel to flow freely.

Thanks for the ideas and I'll send some pictures when it's a "running" machine !

[Anonymous]

Check your plugs, I'll bet they're all black.

[Anonymous]

I found it !!!

FYI, the fuel line that goes from the petcock to the carbs is quite short. It doesn't have any play at all. Because of this, there is pressure on it pulling it towards the carbs which in turn "sort of" pinches it. The gas can flow slightly but when a greater supply of gas (like when accelerating) is required, the engine has been starving.

I found gas that had leaked below this because of some pin holes in the line where it is connected. When it's streched enough, they get big enough to leak.

I FINALLY got to go for a ride !!!
thanks for the advice guys, it got me lookin'

Pat

[Anonymous]

Same issue as before.

When I touch the clutch lever, 4 out of 5 times, the bike stalls. If I'm at idle and I touch the clutch lever, it stalls. Occasionally I can depress it and get going but as I'm driving even if I don't touch it, it stalls after a minute or 2. I can at least regenerate the problem now fairly consistently.

Keith, you mentioned that

"Sounds like a ground or short in the clutch switch? It's only used to start the bike, but if touching it actually kills the bike then it needs to inspected. It could be something similar in the starter switch though. Both switches are connected at one point."

I've looked through my Clymer manual and don't get enough info from it to be able to attack it. Where do I find these 2 switches ? Can they be bypassed ? Do I have to replace them ?

Any advice would be appreciated, I getting frustrated. It's 85 degs up here and I'd love to go for just one ride !!

Thanks
Pat

[Anonymous]

So you kickstart the bike anymore?

I'm wondering why this situation isn't popping fuses. It seems like a short from the ignition +12 to the starting primary circuit is drawing down the voltage for the ignition itself, killing the engine. This SHOULD draw enough current to pop a fuse, but obviously this isn't happening.

First, I'd pull the headlight and examine the wiring mess in there for anything obvious. Next, see if you can follow the wiring diagram to find the +12 side of the ignition switch. Make sure you've found it, using a multimeter.

This is the point where I'd want to splice in a temporary lead which would feed back out of the headlight nacelle and be available for testing. Put a meter on this lead and watch what happens to the voltage available there when you tinker with the clutch switch & related wiring.

As a last resort, I'd do what a lot of people do when the ignition switch / wiring dies: Wire up the ignition entirely separate from the rest of the bike, controlled with a toggle switch. Once you get reliable power to the ignition, you could get really fancy & safe and wire in your handlebar kill switch. It's an ugly but trusty remedy, considering how short your riding season is up there!

[KEITH KRAUSE]

You can also try cleaning up the clutch switch and the starter switch and look for anything wrong like a cracked solder joint or whatever that could cause a short or looseness. The clutch switch is under the clutch lever. And by starter "switch", I meant the starter button.

[Anonymous]

You guys are great !

I think I'll try keith's suggestions first as it sounds likely to be in the clutch lever itself. It did blow the main fuse once in this process. I will wait to see if that happens again. So the clutch lever assembly is easily disassembled ? I'll give it a try.

By the way, we can ride up here anywhere from 10 to 11 months out of the year. people were riding in December and January this year ! I intend to do the same if I can get this worked out !

Thanks again. I'll let you know how I make out.
Pat

[KEITH KRAUSE]

It's been a long time since I played with a clutch switch. If it's similar to the front brake switch inside, then be very careful of small springs or other parts falling on the floor. Put a blanket down or something in case things start flying and rolling around. Just be aware.