Bike randomly died while riding.

[1978GS750E]

I had an '81 GS750E that ran great, but every once in a while, it would suddenly start sputtering, lose most of it's power, and die. I'd let it cool off for 10-15 minutes, then it would start right up again, and run down the road just fine for a while.

It drove me and one of our other resident GS gurus crazy for a month. Figured it had to be a fuel issue, the way it lost power.

Turned out, it was the one and only stock coil I've ever had go bad on me. The coil would heat up, and then stop firing it's two cylinders. Once it cooled off, it worked fine.

Turned out to be a super simple fix, but was a bear to find.

I just had the same thing happen to me on a '82 GS1100E while out in Missouri. Started missing occasionally one morning, cleared up until the afternoon. Felt like it had bad gas to me so I added some fuel treatment and it ran good for another 1/2 day. Until it wouldn't! I cut my trip short, replaced the bad OEM coils and now it runs perfect!

[rphillips]

Agree with Griffin, I never remember me nor any of my riding buddies ever having a coil problem... My "83" 1100E has those yellow Accel coils and wires that previous owner put on, he probably thought they'd give him more HP as many folks did. I'd feel more comfortable and it'd look better if it had orig.

[alke46]

[QUOTE=Griffin;n1771592]I I'd let it cool off for 10-15 minutes, then it would start right up again, and run down the road just fine for a while.

This is such a sure fire sign that the coil/coils are bad. I learned this lesson many many years ago as it happened to me on more than one occasion, starting in my teenage years

[stossboss_gaming_and_news]

If you hear a low hiss from oil cap thats rings. but IF ITS a rather heavier louder type hiss i would suspect an actual holed piston. How do the plugs look? any really white lean looking?

All the plugs were dry and black, memory can be hazy so I'll share a pic tomorrow.

I had an '81 GS750E that ran great, but every once in a while, it would suddenly start sputtering, lose most of it's power, and die. I'd let it cool off for 10-15 minutes, then it would start right up again, and run down the road just fine for a while.

It drove me and one of our other resident GS gurus crazy for a month. Figured it had to be a fuel issue, the way it lost power.

Turned out, it was the one and only stock coil I've ever had go bad on me. The coil would heat up, and then stop firing it's two cylinders. Once it cooled off, it worked fine.

Turned out to be a super simple fix, but was a bear to find.

Sadly I already replaced both coils on this bike this past year, so Im hesitant to put my thinking there, and it had the same (definitely separate to my current one) hot start issue with the older coils. Sort of felt like the starter wasn't getting any juice till everything cooled down. I do have one thick snipped ground cable on the top of my crankcase and I have always wondered if it's related, but in the diagrams I cannot find what it's used for as I the only one similar to it goes to the battery, also connected to a diff bolt nearby.

[stossboss_gaming_and_news]

Did the compression test today... All in the range of 55-65 PSI, engine was cold as it wasn't running. Just no idea why it's so low. Could timing be an issue?

[KiwiAlfa156]

Did the compression test today... All in the range of 55-65 PSI, engine was cold as it wasn't running. Just no idea why it's so low. Could timing be an issue?

Did you have the throttle wide open? Seems strange that they are within 10 psi of each other and all are equally low; service limit is 100 psi, - recommended range from the workshop manual is 128 - 170 psi.

[Griffin]

If your compression is really that low, I doubt you could get the bike started, let alone running down the road. Are you sure you had a good seal on the spark plug holes when checking?

[dgates1]

Some of the cheap compression testers are garbage. Even on a cold engine it should be higher than that if you can start it.

[stossboss_gaming_and_news]

Some of the cheap compression testers are garbage. Even on a cold engine it should be higher than that if you can start it.

I cannot start it anymore, not even with a jump and starter fluid. I'll try again maybe there was something I missed - all plugs out throttle open

[rphillips]

Yes, all cyl. being that equal and that low sure seems like something out of wack in the testing.

[Steve]

Agree with Griffin, I never remember me nor any of my riding buddies ever having a coil problem... My "83" 1100E has those yellow Accel coils and wires that previous owner put on, he probably thought they'd give him more HP as many folks did. I'd feel more comfortable and it'd look better if it had orig.

Please do yourself a favor and check your coils. Verify the resistance across the primary terminals is about 3Ω.

The only "coil problem" I have had was related to "yellow Accel coils" that were installed by a previous owner. My wife's '82 850L would destroy an igniter about every 2 or 3 years. When I finally decided to do some troubleshooting instead of just replacing, I found that the coils were the "high-performance" 0.7Ω coils. The extra current they allowed through the igniter was doing all the destruction. Installing some proper 3Ω Dyna coils fixed that problem for good. It has been 7 years now, it's still running strong (although with a different owner).

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