What size Plug gap do you run ?

With Gerex CDI systems and the requisite low-ohm coils I was told to use a plug gap of 0.060" or 0.065", with 0.060" providing a better idle - this from the creator of Gerex.

These systems are so powerful that I've actually run them with plug gaps of 0.110" after failing to even look at the plugs for many years - the only hint I had was that engine would miss a few times when it was cold and then run well after it was hot. I then decided it was best to take a look at the plugs and I was amazed that the GEREX CDI system handled such a huge plug gap.

I remember when Russ Collins used to run these GEREX CDI systems on his drag bikes, and when Yoshimura Racing ran them too. Pops said that he gained some 3 hp in the upper rpm range of his roadracing Z1 motors.

I called Dyna about the max plug gap to run with its Dyna 2000 system with 2.2 ohm coils. I was told to use 0.024"-0.028". I'd be interested to learn how 0.045" works out for you otakar.

I have been running .040 all last year and I had power out the wazoo. Opening it up another .005-.010 should not hurt. I may try .060 on a set of plugs and see what happens.

otakar wrote:

I opened the gap to .040 from the .030 stock. I never had spark blowout again.

I think I'm misreading this. Does the larger gap decrease the risk of spark blowout? Or are you saying that along with the Martek ignition the .040 gap eliminated spark blowout?

I'm not trying to argue. You just got me worried about the welding the clutch pushrod and exploding cases thing, and I want to make sure I avoid this on my bike!

Was your engine heavily modified when this happened? Should I be worried with a 4-1, drop-in K&N (stock replacement type, not pods), dyna III and green 3-ohm coils?

Thanks for your help.

Yes my engine was modified. 1103, Bonneville cams, Yoshi Pipe. The stock coils just could not handle the turbulence in the engine. What I was trying to say was that with the new Blue Goose coils that even going to .040 gap did not allow the spark to blow out. I will be trying a .060 gap on my GPz as soon as i pull it out. This will be with a stock Kawasaki IC igniter and pickups and Dyna 2.2 Ohm Coils.

just ordered the accel 0142 plugs from Summit....2.25 each...same as the NGK.....i have the accel supercoils and accel wires.....i m going to gap at .40 and see if i see a difference....cheap experiment......

You may want to go as big as .045" In my opinion the Accel is the best cheap plug out there.

otakar wrote:

All three of these are equivalent to the B8ES the two that are U grooved are the Denso and Acell. The Beru is not, that is just a silver core plug that has a wider heat range.
Thanks I'll give them a try.

Last week i set up a set of Denso plugs with a .060 gap. today i removed the NGKs that were in mi GPz and installed the new Densos. I took the bike out on the hiway and was astonished how quickly it got to ten grand+ Never skipped a heartbeat. Idle was also impeccable. I also noticed that i was not holding the throttle as far open at 5K (80mph) I think that the .060 gap with these Dina coils is the trick. These are the cheap old stile Denso plugs just the W24ES-U that are not made any more because they are such old technology.

Well, I got my ACCEL #142 plugs in today. Now I know why Denso Is not suing them for Patent infringement. The plug is EXACTLY the same as the Deso (ND) W24ES-U even down to the stampings into the metal minus the Denso logo, and the fact that the ceramic is yellow and not white. So the ACCEL 142 IS THE ND W24ES-U As far as I am concerned the best plug ever made. Denso discontinued this plug about eight years ago for the new precious metal crap, which is useless to us in the motorcycles. Who cares that the new plugs last 100,000 miles, not in a bike they don't. I have been looking for these plugs now for the 8 years that they have been discontinued. Well, I guess I found them in the ACCEL. :woohoo:

got mine today also....put em in after work and gapped at 40....i will give em a workout tommorow.....

Mine are gapped at .060 and I love it. 10,500RPM and no blowout or even stutter. It would go higher if I let it. Not when my factory redline is 8500. :ohmy:

Here is a Factory .028" to MY .060" According to Dyna it is totality safe for the coils.