Page 1 of 2

Spark plug indexing

Posted: Wed Nov 17, 2010 12:08 am
by mattcfish
Is it worth it? What is the right way to do it.
I've noticed that over the years my spark plugs have become more and more recessed into the head. The last time I checked one plug was pointing away from the intake valve. I put a thin washer in under the plug to get it in the correct position. I'm not sure if this accomplished anything or not. I'm going to be dual plugging soon, so any information on the subject of indexing would be helpful.

Re: Spark plug indexing

Posted: Wed Nov 17, 2010 12:31 am
by Major Softie
mattcfish wrote:Is it worth it? What is the right way to do it.
I've noticed that over the years my spark plugs have become more and more recessed into the head. The last time I checked one plug was pointing away from the intake valve. I put a thin washer in under the plug to get it in the correct position. I'm not sure if this accomplished anything or not. I'm going to be dual plugging soon, so any information on the subject of indexing would be helpful.
It is extremely unlikely that you will see any measurable difference from indexing plugs. There is a theoretical possibility that it could make some difference in the burn, but I've never seen ANY actual evidence that it makes a measurable difference. Considering how the automakers have struggled to achieve every advantage in efficient burning of the mixture (for both power bragging rights, and emissions), you'd think that they would have made indexing a required part of maintenance if there was any measurable improvement.

Re: Spark plug indexing

Posted: Wed Nov 17, 2010 2:09 am
by Motu
Taking anal to a new level - stop wasting time on this stuff and go out and trim your lawn with a pair of scissors,I'm sure there are a couple of blades the wrong height.

I use Bosch Plus 4's - they are self indexing.

Re: Spark plug indexing

Posted: Wed Nov 17, 2010 5:17 am
by ME 109
I once had trouble indexing plugs.
So I went and bought a Hayabusa.

Re: Spark plug indexing

Posted: Mon Nov 22, 2010 12:15 am
by mattcfish
So, am I right in saying this isn't a "must do" modification?

Re: Spark plug indexing

Posted: Mon Nov 22, 2010 8:35 am
by Roy Gavin
The NGK Website has a section on indexing - they claim to have measured a power gain, cant remember how much but it is free horsepower/ better fuel economy for a moments work.

Re: Spark plug indexing

Posted: Mon Nov 22, 2010 10:31 am
by vanzen
Obviously not a necessary proceedure,
I have always thought indexing a 'good idea' on a hemispherical head with a single plug.
A remnant of old scool hot-rod theory / practice that still exists in my head, I suppose,
and I am in the habit of indexing plugs on (both 2 & 4 plug) old boxers.
Be that as it may, I have no data to provide as proof of the benefits.

Re: Spark plug indexing

Posted: Mon Nov 22, 2010 11:34 am
by Duane Ausherman
Hey, it is your bike and your hobby. Obesss over any little thing that you wish. I have never heard a single comment that it could be harmful.

In a street bike ridden as most ride a BMW, it has to be a waste of time and effort. The same could be said for pruning that little stem off of your rose bush, or using the right salt for cooking THAT one dish, or lining up the slots of the screws that attach the tank emblems.

If you really want to improve the performance of your bike, step on a scale. Right there are probably the easiest 20 lbs to remove from the bike. That would be the cheapest performance improvement possible for your bike and you too.

maybe it was the benzedrine in the Olvaltine ...

Posted: Mon Nov 22, 2010 12:34 pm
by vanzen
Duane Ausherman wrote: If you really want to improve the performance of your bike, step on a scale. Right there are probably the easiest 20 lbs to remove from the bike. That would be the cheapest performance improvement possible for your bike and you too.
This skinny old grey moto-psycho junkie hasn't even got 1 pound to spare !
Not even after drinking 48ozs of Bell's finest Two-Hearted Ale !

... The 20 HAD to come off a properly indexed bike.

Re: Spark plug indexing

Posted: Mon Nov 22, 2010 1:56 pm
by Major Softie
That may be true for you, Vanzen, but there's definitely hidden horsepower in my "physique," and I know there's quite a few of those hidden ponies in many of the rest of us.