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Littering And...........
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1,073 Posts
Discussion Starter · #1 ·
So I got this gem of a bike for $230. cleaned the carbs, new oil, and coolant and she runs wonderfully. Issue is when I ride for about 10 minutes the bike doesn't overheat but just gets to operating temp (says the gauge i know it works because it was way hotter the other day) and starts to run on 3 cylinders then 2 then 1. then dies. obviously. So i've tried different tank positions, res and on to no avail. refuses to start up til its cool again. need some help
 

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sickboy
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3,544 Posts
IF its not a fuel problem I would put my guess on the ignition module. Ive seen it before where when cold an engine starts fine, but as it gets warm the ignition module gets hot and expands and the contacts inside separate. I would let the bike get warm and die, then pull a plug boot and check for spark.
 

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Littering And...........
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1,073 Posts
Discussion Starter · #3 ·
But it starts bak up with persuasion and the ignition module is under the seat far from exhaust and engine.

It's getting gas from the pump and it's got spark to start back up again. It'll start up then when I go to leave it will sputter then ultimately die when I let off the throttle.
 

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Registered
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740 Posts
Doesn't necessarily need engine heat, the flow of current through the box causes heat which causes it to malfunction as it warms up from the ignition being on.

It's becoming a more common problem on 80's bikes now. The ignitions of that time seem to have a lifespan of ~25 years, and a lot of them are starting to check out now. Unfortunately unless you're a total electronics whiz, there's not really anything you can do aside from find a replacement, or if it's worthwhile to you fit an aftermarket generic ignition unit.
 

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Littering And...........
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1,073 Posts
Discussion Starter · #5 ·
Yeah and the unfortunate thing is I can't check it to see if that's the true problem. But I have a feeling if that was it it would die out altogether. Meaning I wouldn't be able to start it back up at all. Last time a box went bad on me I had to jump it with a car to get it to work.

Otherwise I'm going to check valves and also check the head bolts and make sure they're tight. I've heard of these bolts not being torqued properly and causing issues but I don't k ow at this point.
 

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sickboy
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3,544 Posts
HMMMMM well, to throw another idea out there... Check your coolant to see if its dropped, maybe a bad head gasket? Bike gets warm, coolant leaks into cylinders drowning out the plugs, starts up again after they dry out?
 

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Littering And...........
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1,073 Posts
Discussion Starter · #7 ·
Um yeah I didn't think about that. But I noticed I filled it up when I got it then I checked it 2 days ago and it was empty. But it didn't smell like it was burning coolant.

I'm definitely doing a full compression test on it tonight, once when warm and running good, then once when it finally dies out.

Hopefully that'll give me an idea if its a head gasket or not.
 

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sickboy
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3,544 Posts
ya that's the way to tell. fill the radiator, do compression test n look for bubbles in radiator
 
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