spark plug indexing
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Road Master
Joined: Nov 2006
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From: Grosse Ile, Mi
spark plug indexing
Anyone with experience in doing this. I did it recently with my bike and it seems to have made a difference in its running a bit better. Or, is it just my imagination?
Tourer
Joined: Mar 2007
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From:
RE: spark plug indexing
This is why there are side electrode sparkplugs..no need to index, the spark is "exposed" to the combustion chamber.. Airplane reciprocating engines have had them forever...the combustion chambers are two large to have a conventional type plug. I have read that in automobiles it is for mainly improving fuel efficiency.
Stellar HDF Member
Joined: Apr 2005
Posts: 3,108
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From: Lincolnton, NC
RE: spark plug indexing
Indexing was originally done to gain clearance between the electrode and the piston dome. It has since been proven to promote flame travel. Not worth it on a street engine of any type, too many other places to gain more power first.
Road Warrior
Joined: Jun 2005
Posts: 1,334
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RE: spark plug indexing
In theory indexing the spark plugs will make any engine run better, but the change is so small that it is unlikely that you are feeling it. If you have the time, then you can only do good by indexing spark plugs, but the gains tend to be very small if at all.
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Outstanding HDF Member
Joined: Jun 2007
Posts: 3,306
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From: Bellville, Tx
RE: spark plug indexing
On my carbed Evo, had been running once in a while at the local drags and screwing with plugs I noticed when I indexed the plugs so that the electrode was aligned with a clear path to the intake, the plugs ran a lot cleaner. I do it now just for that reason and it does work. Its probably better on the daily rides than on the track 'cause of the varying speeds and loads. Or maybe I'm just a little ****. Don't see any performance increase though.
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Road Master
Joined: Nov 2006
Posts: 861
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From: Grosse Ile, Mi
RE: spark plug indexing
Well.......I kinda thought that it was my imagination playing tricks on me.I guess so. You know what they say, things run better after they are waxed and polished, etc. 
Road Master
Joined: Jun 2006
Posts: 933
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From:
RE: spark plug indexing
You need to pull the heads to index plugs properly.The open part of the plug should be centered on the intake valve stem.I doubt it will make a difference on any street engine.I used to run analcohol engine and it didn't seem to help that engine.It wasn't a bike though.