82 XS400 electrical issue

I have a friend who owns an 82 XS400 that's having an odd electrical problem.

While it was running one day, it died on him. He was unable to get it started by pushing the start button (he did say the relay clicked fine). He is able to push start it though. However, a few minutes later, the same thing would happen - the bike just dies. He can push start it and it'll run for a few minutes, then it dies on him again. He did say he just put a new battery in it recently.

I did not think to ask him if anything else electrical dies as well (headlight, turn signals, etc), so I couldn't answer any more specific questions.

He's not interested in putting any more money into it, but I'm curious to know if anyone has any ideas as to what the cause of this problem may be and what it could take to correct it?

If it's likely to be a simple fix, I might just take it off his hands and fix it up over the winter.

 

If it still has the original fusebox, throw it in the trash. The connections get old and crusty and intermittently stop working. Besides, a modern fusebox or inline fuse holders will let you use modern blade fuses.

Of course the real question here is, why didn't he start it with the kickstarter?!

 

it was probably a maxim or seca 400...no such luck as a kicker pedal...lame, I own one and it ticks me off too

 

Ok, if those connections are good, any other suggestions to check?

Yeah, he said it was a 400 Maxim, which would explain the lack of a kickstarter.

 

If the fusebox has already been replaced, then see if it has spark the next time it dies. Could be a failing semiconductor or bad solder joint in the ignition module that opens up with heat.

I think we need more info -- as you said, what happens to the lights etc when it dies? If they go off too, then the ignition key switch could be dirty or bad.

You said the relay clicks when he tries to start it after dying -- does the starter spin or not?

Also, what is the battery voltage with the engine off, engine idling, and at 4,000RPM? Just because the battery is new doesn't mean the charging system is keeping it charged.

 

Check all grounds ....
Use a meter to check the voltage with it idling at 2K rpm or soo...
Could be the reg/rect unit
OR...
If the starter is just clicking and not trying to turn over,,,,
battery... need to be charged or replaced....

 

I have an XS400L and it used to do just that to me. I finally found a way to get it working, of course after having checked the fuse box and everything else. I was just about to resolder everything in the TCI box, as one rider did and solved his problem doing so. So I went over many of the connections in fact. I might have repaired weak connections doing this.

Then I read somewhere on day that the alternator on these bikes are auto-activated - or whatever term he used - and need the engine to run over 4000 rpm to get going. Wow! 4000 rpms?

Now when I start this bike, I rev the engine over 4000 rpm on startup (actually I rev it up to about 6000 rpm for a few seconds then bring it down to 4000 for another couple of seconds, then down under 3000 for warm up). Since I've been doing this, it never has quit on me. If I fail to do this, it will quit on me after 30 seconds of running or so.

Is this only coincidence or have I hit on the solutions for this bike? Anyway, I'm riding my XS400L!


Edit: of course, you need a well charge battery.

 

The actual RPM is somewhat closer to 3,000 -- if there's a wall or something in front of you, you can see when it happens because the headlight suddenly gets brighter. But I use 4,000 just to be certain.