Correct plug gap with Dyna S

1976 KZ900, 1015 block 10:1. Anyone got any thoughts on the "correct" plug gap when using a Dyna S? Thanks.

I left my gap stock when I went to a Dyna setup, but have always wondered if there was any benefit to running it wider.

If the turbulance in the combustion chamber is such that the cell size is larger than the spark, there are folks who say a longer spark has a better chance of missing a cell in which the mixture is not right for ignition. I'm no fluid dynamics wiz but I seriously doubt, that by the time it's all compressed, there is any part of the mix that is not right for ignition. The same argument is applied when touting the goodness of multiple sparks.

Why not give it a try with soem different gap sizes and report back?

-Duck

Spark Plug Gaps
When running a Suzuki or Kawasaki with a Dyna-S and high performance coils set plug gap at .026. When running an MSD or Dyna-4000 Ignition system set plug gap at .018.

I hope this helps Art

Someone remind me...what is the stock gap range, I forget and don't have my book in front of me?

.7 to .8mm about .030"
I have a dyna-s with dyna 3ohm coils and was going to try .040" but was told to just stay at the stock plug settings buy Jeff at Z1.

I set my plug gaps to .032"... I test hundreds of carburetors... some very rich for my stock bikes and don't foul plugs. I do believe that there is some benefit in a slightly larger plug gap when running higher powered coils. The Dyna S part of the package doesn't have much to do with the plug gap increase but the coils do I think.

I ran .040 last summer with dyna-s, accel 3 ohm coils, battery-relay mod, and 8.8mm accel wires. Didn't have any problems with plugs fouling, they ran a nice light brown color. But if you have stock coils/wires then run the stock plug gap.

Thanks everyone for all the input. Sounds like a resounding concensus of anything from 26-40 thou! I'm actually running my plugs at 39 thou right now (I have absolutely no idea why?). Think I might close the down to somewhere a touch south of 35 and see if I notice any difference.

Thanks again all.

I am running Dyna S with 3 ohm Dyna coils and Dyna 8mm wires on my Z1R. Been using .040 gap with no problems. Was told a wider gap creates a "hotter" spark.Ride safe......

wiredgeorge wrote:

I set my plug gaps to .032"... I test hundreds of carburetors... some very rich for my stock bikes and don't foul plugs. I do believe that there is some benefit in a slightly larger plug gap when running higher powered coils. The Dyna S part of the package doesn't have much to do with the plug gap increase but the coils do I think.

this is what i do also...set everything to .032.....never fails..

Sounds good, might give me something to tinker on over the weekend. I think mine are still set around .75mm.