Dies after 10 to 15 minutes of riding

E-judd

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I'm new to this forum, so please hang with me. I have a 1978 xs650 special, not a whole lot has been changed mechanically other than: a pamco ignition, pod air filters, and cut off the mufflers leaving headers open and wrapped. With that being said I will ride my motorcycle for about 10 to 15 minutes and then it quits running. It will not restart until it cools down for about 30 to 45 minutes, during the time that it is too hot to restart it has no spark. Over the past few weeks I have had my ignition tested, and came back good other than a weak magnet in the rotor which was replaced, I have also replaced my battery, coil, and alternator brushes. Still my my bike dies after 10 to 15 minutes I'm completely baffled as to what is going on, does any body have any help for me?
 
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Are you positive there's no spark? Did you put new plugs in when you did the pamco swap? If you find that you actually have spark, it may be your gas cap vent. Try popping the lid next time you go for a ride and see if that helps.
 
I'm positive I have no spark. I put new plugs in it, and I have tried the popping the gas cap and riding it. Nothing changes.
 
When you installed the Pamco, did you install a new ignition coil as well, or is it an older coil? Ignition coils can increase their resistance as they heat up. Substitution with another coil may be required.
 
When I first installed the Pamco last season I bought the kit that had a new coil with it. About a week and half a go I bought another coil and installed it, still doing the same thing.
 
Do you still have the original 4 position fuse holder? The clips weaken and with some added oxidation, the resistance can increase and cause voltage drops. There could be a time lag when this happens.

Replacement with automotive blade type fuse holders is recommended.
 
You say no spark, but no gas tank vent can cause a 15 minute run time.......... does it shut off or slow down and quit.
 
I still do have the oe fuse block. From what I can see all the fuses are secure and free of corrosion, but I have been looking into replacing it with blade style fuse block.
 
It actually shuts off, but if I leave clutch engaged while I coast it will more or less diesels from the heat and backfire through the pipes from the raw fuel for a few seconds, and then it won't restart.
 
I still do have the oe fuse block. From what I can see all the fuses are secure and free of corrosion, but I have been looking into replacing it with blade style fuse block.

it is the connections to the fuse clamps that fail, if you have a weak connection, the heat from resistance increases resistance until the circuit fails. I would replace the whole thing right away with blade type fuses. Also, I have had walmart batteries fail within a week for no reason.
 
I will get right on replacing my fuse block. I have an Interstate battery which I have rarely seen them fail for no apparent reason.
 
please post if you find the fix, my bike is doing the exact same thing and its driving me crazy. i have literally been down the same path and replaced exactly the same parts. starting to lean towards my kill switch. i haven't tried the tank vent yet. if you figure it out give us a holla
 
Have you tried taking your petcock off and disassembling it, cleaning it out? I had this problem and the once and It was a combo of the gas cap and a clogged up petcock.

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Have you tried taking your petcock off and disassembling it, cleaning it out? I had this problem and the once and It was a combo of the gas cap and a clogged up petcock.

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Heres ANOTHER one! I've got the same issue, I think? '81XS SH, new battery,a recent build, Had BS 34 carbs and now Straight pipes w/ those little 4" baffles, uni-foam filters, it was back firing, grumblin, sputtering at frwy speeds and after it got good and warmed up it dies.(This is after a build and nearing completion) When I got my BS 38's on it ran WAY better, reved quick, changed jets (1 up on mains and pilots) and it seemed like everything was good. Ran around locally with no issues. Decided to check out those mains and hit the freeway and in 4 miles it sputters a bit and dies. Won't start till its cool. The bigger jets seemed a big improvement...until it dies as before! I have dropped my needle clip down one- which raises the needle- right? Enriching it, correct? Now Im reading I should probably need to go up from factory on the clip (to slot #2, becuse the larger mains makes the mid range richer? But it seemed to run great! It was sputtering, backfiring, grumbling, dying ect with bs 34's, after the switch it reved quick, all issues SEEMED resolved, until blaaauuuuuhhhh. dead. I suspecting I have two problems and am trying to fix it with carb tweeks. It just seems elect. but truly Im stummped. Been reading a lot here, lean toward coil, ignition box, I just dont have the cash to buy one of everything till it works. Sure could use some help! I need it runnin before my car craps out!
 
Oh, I just replaced the petcock but Im gonna go try openin the gas cap, ck tci grnd, how to test my coil? Better throw in new plugs hugh?
 
I had a similar problem wuth an older intercptor, when the bike got hot it would quit. Almost like it was out of gas. It was actually a bad coil, when one of the coils got hot it would quit working, only when it was hot though. Run it until it quits again and then do a resistance test on the coils. Be careful though they will be hot. ;-)
 
That symptom is sometimes corrosion somewhere in the spark lead/coil connectors. Especially if you spark plug boots are the removable type, water likes to get in the end and corrode the hell out of the copper wire. Remove the leads from the coils if they're removable, pull the boots off the other end and have a look at the copper in the lead. If its dark rough it up bright and shiny again. If they look like green fuzzy pipe cleaners you can try cutting them back an inch to get to fresh copper.

Clean all the copper bits in the boots and all the coil connectors and lead terminals with a small file or twist of sand paper and reinstall them.

The coil itself can be the problem too but cleaning connectors is free so try it first.
 
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