#1 plug fouling

[chrisbock]

I have an issue with the #1 plug fouling on my '81 gs850. The carbs are clean (complete disassemble and dip). I've recently re-jetted it with a stage 3 dynojet kit (k&n pods, 4-1 mani). The valves were also recently adjusted. I have also put new caps and plugs in.
A motorcycle mechanic friend of mine has taken a look at everything and is stumped. If the coil was bad, then the #4 plug would show the same signs, but the rest of the plugs look great. He said I should probably get new coils as the next step, as the spark looked fairly weak. Then again GS's have famously weak sparks.
This is an expensive "probably", as dyna coils are around $300 for a pair. I have found a deal for a set with the dyna s ignition and wires for $300 after shipping. Still, $300?!!!
My question is, could the coils be the problem if only one plug is getting fouled? My mechanic had said somthing about the how the coils were built and rarely can go out on one cylinder.

Thanks

[Agemax]

swap the HT leads on the 1 + 4 coil around, so #1 is on #4 and vicy vercy. see if the problem moves to #4 spark plug.
if not then it is not the coil

[tom203]

If Agemax swapping eliminates coil as the problem, then it's either the spark plug (doubtful) or a carb mis-adjustement.
Somewhere I have a set of stock coils off a 82 850 that tested good- if you are interested ,PM me. I will sell for $35 plus shipping

[tkent02]

I have also put new caps and plugs in.

I would suspect this, just since it's the last thing you messed with.
How is the connection in the cap?

[jacora]

If Agemax swapping eliminates coil as the problem, then it's either the spark plug (doubtful) or a carb mis-adjustement.

I agree with Mr. Agemax, it should be a bad plug or a carb adjustment problem. Some years ago I had a similar situation with #3 and #4 plugs, at the beginning I suspect (like you) from the coils, in fact, I purchased a set of dyna coils and the problem stayed like before, then I went to carbs and I found that they had the wrong type of pilot jets and not screwed in up to the bottom. Once I changed to the right pilot jets I had no more problems with fouled plugs.
jacora

[chrisbock]

Thanks for the replies. I'll try swapping the 1 &4 wires and seeing what happens. I tried that before, but I had new plugs in, and didn't have any issues with fouling. It was after I swapped the caps, so I thought I fixed it. I'll give it a bit more time. The connections are good, and my mechanic swears by the carbs. They seems to be most effected when I'm in mid range, but all the needles are at the same adjustment. All pilots are seated, and all the same size. I'm getting a general consensus that its probably not the coils though. I was told that I could try putting in iridium plugs that are foul resistant, but I want to actually fix the issue. Would putting in the dyna S ignition and dyna coils provide a stronger spark than the weak stock setup?

[tkent02]

The stock setup isn't all that weak, if it's working correctly. I have never had a fouled plug in many thousands of miles on many many GSes. If there is a problem, fix the problem.