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Oops!! I'm using Iridium resistor needle point plugs in me 100RS with no ill effects to date. Should I change 'em ? Why? hools.

Anyone else bother to index plugs ? May not make much difference but it can't hurt and whatever marginal effect it has whether positive or negative is at least made the same for both cylinders.

I have never bothered.

Best numbers I've seen on combustion chambers like Airheads have is under 1%, and that is with experimentation on a dyno for best possible position. So, the best possible scenario is around .5 HP, and average is probably more like .25, and that's with experimentation on a dyno.

But, knock yourself out.

lrz wrote:Motu-those are Bosch of some sort?

They are Bosch W78 Super 4, they cover the 7 and 8 heat range. I had them in a car I sold, and have been using them in the bike for 4 years, one day they will wear out and I can use the other 2. I used to fit them to cars that had difficult sparkplug access - they last as long as a platinum at the fraction of the cost. They were in the car (Lada 2104) for 20,000km, and have been in the bike for 25,000km, and look like they should go another 20 or 30,000km no problem. I'm sure someone will say they don't work....and yes you are correct, my bike hasn't been running for 25,000km.

Before anyone makes a comment on the mixture, it was a plug chop with these....

When swapping brands remember that NGK 's heat range goes the other way from most , so the equivalent to the cold 3 grade Champion in Nicole's Enfield Electra lean burn is the 9 grade NGK.

A 3 grade NGk would probably kill it.

It's a Japanese thing, Denso also have the higher numbers being colder. I guess it makes sense to them, but it seems like saying a 10mm bolt is smaller than an 8mm bolt.

We never bothered to index plugs in my dealership. Too expensive for too little and customers would be very unhappy paying for it. We didn't do it on our race bike either.

Sorry for the dumb question, but can someone tell me what "indexing" plugs means?

dougie wrote:Sorry for the dumb question, but can someone tell me what "indexing" plugs means?

Setting the ground strap on the plug to a certain position in the head to aid or equal the flame front on both heads. Makes a lot of sense in theory, but not so much in practice.

Garnet wrote:

dougie wrote:Sorry for the dumb question, but can someone tell me what "indexing" plugs means?

Setting the ground strap on the plug to a certain position in the head to aid or equal the flame front on both heads. Makes a lot of sense in theory, but not so much in practice.

Thanks Garnet.
Sounds like one of those "file under anal" things.
Airheads and Bings - puff of air, pinch of gas, light a match.