1981 GS1000G missing on 1 and 4

[Johno]

My 1981 GS1000G has developed a sudden miss near home after a faultless 100 mile morning run.

Pulled all four spark plugs and #1 and #4 are black and sooty while #2 and #3 appear tan colored.

Cylinders 1 and 4 operate from the left coil. Apart from swapping coils is there a test to check operation.

Do I need to test the igniter and the wiring to the coils?

Checked the search but no luck.

Any suggestions or tests I need to conduct?

Valves checked and carbs balanced 300 miles ago. Bike was running sweetly and suddenly developed the missing about a mile from home.

[salty_monk]

Sounds like the coil or wiring to the coil. Check it's getting a healthy voltage then check that the plugs are firing by holding one near the head whilst it's plugged in & turning the bike over on the starter.

Cheers,

Dan

[Zooks]

I'd also test the coil first.

[TheCafeKid]

Was that true electronic at that point, or did they still have the mechanical advance in 81? Ive seen some guys say they had problems with the ignitor going out on one side (likely more the pick-up i would think) But Im in agreement thus far, sounds like the coil is toast, or the leads to that coil.

[Johno]

Thanks for the suggestions guys.

The 1981 GS1000G has electronic ignition.

So far I have got the tank off and will check the wiring to the left coil first.

On first inspection there appears to be some loose binding tape on the wiring harness.

This is not the original wiring harness. I had the bike stored for fourteen years and some rodents had a chew on the wiring under the tank. I bought a second hand loom from a wreckers (breakers yard) and replaced the loom. However because the missing is so consistent and not irregular or intermittent which you would expect from a loose wire, I guessing that the left coil is cactus.

The motor might be the bikes strength but the 28 year old electrics are the achilles heal for reliability.

[flyingace]

My 1981 GS1000G has developed a sudden miss near home after a faultless 100 mile morning run.

Pulled all four spark plugs and #1 and #4 are black and sooty while #2 and #3 appear tan colored.

Cylinders 1 and 4 operate from the left coil. Apart from swapping coils is there a test to check operation.

Do I need to test the igniter and the wiring to the coils?

Checked the search but no luck.

Any suggestions or tests I need to conduct?

Valves checked and carbs balanced 300 miles ago. Bike was running sweetly and suddenly developed the missing about a mile from home.

Why would you not do the obvious (swap coils) when it is the most conclusive test? I don't get it.

[Johno]

Missing problem on GS1000G solved

Pulled the tank and unbolted the left coil.

The orange wire to the coil had broken and was swinging loose!

The original wiring loom was replaced but the wires running to the coils were repaired and soldered.

The last valve adjustment (removing the rocker cover) must have disturbed the wiring and broken the join. It's a tight fit under the tank.

Did a temporary solder repair job but the wiring loom requires more attention to ensure long term reliability.

A good outcome and luckily happened close to home.

[SqDancerLynn1]

At least that was an easy fix.