GS450T Shuts off Randomly

[spaceguyspiff]

Hey all,

I recently purchased my first starter bike, a 1981 GS450T and I had few problems with it when I first purchased it. Recently though, it's been shutting off randomly. The battery is relatively new, and I recharged it, checked water levels and whatnot, but still she shuts off left and right. It's usually when I'm stopped at a light. I'll be waiting and then when I put it into first, give so gas to it, it just dies on me. The engine is full. When I took apart the fuel system, it was running well. In order to get it running again, I'll usually have to pull over, wait until there's no traffic, get a running start hop on then kick in the clutch while starting it.

I really have no idea what it could be, besides a bad contact, but I'll be checking that out today. I did when I was doing some routine maintenance on it a couple weeks ago, but it was fine then...

Any help would be greatly appreciated. Thanks guys.

[TheRedlineMan]

Don't really know that model, but if it has a clutch and/or sidestand switch then I'd be checking there first.

[Nessism]

Is the bikes maintenance all up to date? Valve adjustment, carbs cleaned, intake O-rings properly sealing, air filter serviced, spark plugs clean, spark plug boots in good condition? It’s hard to diagnose a problem unless you have a good foundation to build on.

[nabrams]

I had the same problem with my first GS450 (had it for seven years - got it with 16K miles and I put an additional 11,000 miles on it - great bike). In my case it was three electrical issues combining to make up the problem:
1. The R/R was letting 17 volts through (max should be 15 - see MANY other posts on this), overcharging my battery and boiling it, but not enough to blow main fuse.
2. The clamps that hold the main fuse were dirty, which increases resistance especially after heating up due to over-current from the R/R.
3. The fuse was really old and had high resistance, which made it function "partially" - good enough when cool.
The result of the above is that eventually (after running for a while or after a few minutes - depending on heat levels) the resistance goes up high enough that not enough current can get through to juice the ignition components with the lights as well - the bike shuts off (even though there may be enough current for the lights). The amount of time you spend re-starting is just enough to let it cool down enough.
I also would have to re-fill and re-charge my battery way too often.
After replacing R/R, fuse and cleaning fuse clamps the problem never re-appeared.