GS850 Won't Run Properly

[Steve P]

I have a 1980 GS850. It gives me a lot of problems. The bike is hard to start and won't rev up. Thought it was a carburetor problem, (carb has been soaked and thoroughly cleaned). Now I think it may be electrical. Have 12V at the battery and the fuse that goes to the kill switch, when I check the orange and white wires going to the coils with the key on I only show between 8 and 9 volts. Had it running the other day, real hard to keep it going. When I shut it off I looked at number 3 and 4 plugs, they were black and wet with gas. Number 1 and 2 exhaust pipes were hot, 3 and 4 were cold. Please help. Thanks

[wizard]

It wouldn't necessarily be the coils or their connections being bad, as cylinders 1 and 4 run off one coil while 2 and 3 run off the other coil. I would clean the connections thoroughly if you're only getting 8 or 9 volts. My first instinct would be to examine the wires from the coils and to test the resistance of the spark plug caps. That is assuming that the carb cleaning was done right and the carbs are properly set up and visually synchronized. If that hasn't been done, mention it. The technical talent on this site can and will help.

[mark]

I agree, go through your connections, from the handle bar on down and clean your connections. 8 or 9 volts is too low. Check especially the ground connections that connect to your battery box, they are always suspect. I gained a 1 1/2 volts by cleaning all my connections. Your battery needs to be in good shape too.

If your bike is stock (is it?), the airbox has to be sealed perfectly for your bike to run well. Even if your everything else is perfect on your bike it won't run worth a darn if the air box isn't on or sealed right.

Also check your petcock to see if its operating correctly. You could be sucking gas into the #3 carb through the vacuum line if your petcock gaskets are leaking.

Have you checked your pilot air screws? If they are screwed in too far, they'll flood your bike and foul your plugs. Carbs synched? Floats adjusted correctly?

I had the same problem with my 850. It turned out to be a lot of things that just weren't adjusted right, and cleaned good. Have a few new plugs on hand, I fouled a few plugs and after that they wouldn't fire.

[dpep]

Verify you have the plug wires hooked correctly. Something doesn't sound right. The two middle cyliners should be wired to the same coil.

[bwringer]

Where are you? Might be an experienced GS-er in your neighborhood.

The advice so far is great -- let us know what happens. There are way too many parted out 850s sitting on eBay because someone gave up on a relatively simple problem!

[Joseph Masnyk]

check the kill switch make sure there is no corrosion and also check the spark plugs are in properly and wires are good.

good luck,
Jo

[snowbeard]

barring your coils being connected to the wrong plugs, the fact that three and four are cold sounds like it might be a fuel supply issue, but the fact that the plugs are wet contradicts that...hmmm.

[mark]

I'll just repeat, I had the same problem with my bike....sometimes 3 and 4 wouldn't fire....then it would run on three, two, and one cylinder. Different cylinders would work at different times, but rarely all four together....no consistancy. The cylinders that were not firing were always gas soaked.

For me, I think the problem was a combination of poor spark, a poorly tuned carb. Cleaning all electrical connections, getting proper voltage to the coils, new spark plug caps etc., and getting the carbs adjusted half decently cured it.

[adamd]

Any update on this? I have the same prob...