Help! Bike runs perfect for 10 min then dies

Ben42

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Hi,
I have an 80 xs650 special. I've been riding it for 3 yrs now and have done minimal work as it is in good condition.

I just took it out for the season after it sat in my garage for 2 months. It has a new AGM battery I put in when I bought it.

The problem:
I start it, it warms up, turns over, after 10 to 15 min riding and/or idling it shuts off instantly. No petering, no gag, just OFF.
It can't be kicked or elec. started after it dies. After about an hour I can start it but it stays on for 5 min. The headlights and turn signals all operate normal through all of this.

I had the ignition coil checked and reads inline spec. I also thoroughly cleaned the carbs and new petcock. I dont believe it is a fuel issue...

I called a couple of shops in town and they said it could be the stator going bad. It seems like its warming up and an electric part is turning off.

I'm out of ideas and wanted to see if I'm missing something before I take it to my one overpriced shop in town.
 
Many times an ignition coil will fail when hot but work fine when cold(er). If you had yours tested cold then it might still be the issue. The fact that the bike started again after sitting and cooling down some is also in line with the coil failing only when hot.
 
Ben42, your Oregon location is vague however there are some small privately owned shops who do good work for a fair cost.
In the Portland west hills is Cycle Metrics. Gary, the owner and one man operator is one of those few very honest and competent private motorcycle shops left. He was infact a Yamaha dealer when the "Specials" did come out and knows Yamahas very well
His shop is up in the west hills and riding those curvy roads there are fun as well.
Bonus, he is friendly and has spare parts.
https://cycle-metrics.business.site/
;)
Depending on the whole situation, sometimes a private shop diagnosis is a good choice.
 
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If you know the problem is going to persist, carry a plug wrench with you. When the bike quits, pull a plug, ground it against the engine and see if you have a nice BLUE spark, orange/yellow won't do. Is the plug wet or dry ? If dry, lack of fuel. If wet and lookin' kinda black, too much fuel, the engine is flooded.
 
A long shot but check the fuel tank is venting. Years ago a mates bike had similar symptoms due to over enthusiastic use of chrome polish blocking the vent. So as it ran it was creating a vacuum in the tank until eventually no fuel could get through. With the bike stood a while the vacuum eventually leaked off and it would run again. Only figured it out when he opened the tank cap and heard it gasp!
 
Many times an ignition coil will fail when hot but work fine when cold(er). If you had yours tested cold then it might still be the issue. The fact that the bike started again after sitting and cooling down some is also in line with the coil failing only when hot.

I am there Also .. No fuses Blown and no misfiring before ..Points to a loose wire or temperature dependent short
That via the thermal expansion or vibrations shuts down
The headlights and turn signals all operate normal ---> means that the charging is OK
Never heard of a carburetor fault not misfiring a couple of times and both sides dies at once. ---> Out of the Question.
In the US I think you have electronic ignition Box and electronic Regulator.
Sounding like a broken record or parrot saying the same thing over and over ..The wiring to the ignition service is a first.
And Ground wires ..that nothing is loose and so

I would also stare down the Kill Switch on the handle bar as a suspect in the ongoing investigation.

If you are confident draw own wires please tell we ( I ) can do a test wiring suggestion.
 
A long shot but check the fuel tank is venting. Years ago a mates bike had similar symptoms due to over enthusiastic use of chrome polish blocking the vent. So as it ran it was creating a vacuum in the tank until eventually no fuel could get through. With the bike stood a while the vacuum eventually leaked off and it would run again. Only figured it out when he opened the tank cap and heard it gasp!

I had that exact problem many years ago, Yamaha YDS7. Same symptoms. Worth eliminating a blocked tank vent.
 
Thanks for all the responses guys!

@Machine I'm in Bend, Oregon. Thanks for the beta!

On the fuel tank terms, I read about that in a different thread and tried to see if having the cap venting on or off made a difference...still the same problem persisted. I feel like my gas cap is so old and degraded that there is no way for it to seal like that!

The issue is almost like clockwork every time. It never peeters out, always instant.

Update: I found the ignition coil was not putting out after warming up. Just ordered one, nothing too fancy. Hopefully it works. Thank you @5twins

I'll keep yall updated after install.
 
Many times an ignition coil will fail when hot but work fine when cold(er). If you had yours tested cold then it might still be the issue. The fact that the bike started again after sitting and cooling down some is also in line with the coil failing only when hot.

try heating the coils with a heat gun to about 150 degrees then test.
 
After installing the new coil, the same issue persists. It started great! Definitely noticed the difference from the old coil. It stopped/turned off immediately after about 10 min at idle. There was a backfire after it stopped. (This sometimes happens)

Not sure what to do next...

I checked the start/kill switch and looks rather new and clean. Is there a way to override the switch to make sure it is for sure not that.

I'm fairly new to tinkering on motos, so please describe with elementary electrical answers. :)
Thanks guys!
 
I assume you have a stock electronic ignition
Others here know more about it than I do
I would check wiring especially ground wire from ignition parts

Update: I found the ignition coil was not putting out after warming up

Fuse box not loose fuses.
Please confirm that it is stock wiring with stock ignition
If no one else has the solution we can work forward on that
But Ground from electronic ignitions had been a problem on half a Dozen bikes last 6 months.
One fault finding trick has been draw a separate ground wire alt the way to the battery. .
 
The next step is to find out what ignition system you have... I don't believe you've said. 1980 Had the TCI. Is there a black box attached to the bottom of the battery box, single connector... slightly larger than a cigarette pack?
 
Stock ignition and wiring. The only electrical I have changed is the rear tail light, signals, and battery.

Yes it is a tci, 1980 xs650 special II

@Jim yes there is one. I have inspected it, no blown areas or dirt. Should I look for something specific?
 
Unless you're an electrical wizard, the only way to know it's your problem is to swap it out. They're very hard to come by and not cheap when you do. There's an alternative for under 20 bucks. Have a read here.
 
@Jim thanks I ordered one and should be here tomorrow.

In the meantime, I took a look at the alternator and the brushes and copper looks to be in good shape.

I also tested the charging system and reads 14.8v at idle and 12v when it turns off. So it seems like everything is charging correctly.

Still considering swapping in a whole new ignition system from Hugh's handbuilt.

Is there any other way it could be fuel related before I take the plunge?!
 
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