Topic: spark plug indexing

[keith64]

Has any one used those spark plug indexing washers to index the electrode on the plug to the intake side of the cylinder for more power, and does it make a difference or really work.

[oldbiker]

In sixty years of riding bikes, I have never before heard the suggestion that the position of the plug electrode could make any difference. You could  always try some of those surface discharge plugs that don't have a single side electrode if you want to experiment.

[kghost]

Used to be an old race car trick with blower motors (supercharged). I don't think you'd notice any difference on a motorcycle.

[Raul CB750K1]

The position of the electrode have to be aligned with the intake valve, but also with Jupiter and Uranus. That will give an extra 20+ BHP.   


Raul

[kghost]

DO you have to have the ball lined up too?

[Raul CB750K1]

No, it's enough to have it over the bike's centerline to avoid unbalance... 

[Einyodeler]

Oh no! You have to ride sidesaddle

[bassrocker]

Just to add a couple cents:

The new mechanic at my local shop just graduated from AMI down in Florida and completed the dyno training as his last course. One of things they focused one was indexing spark plugs.

From what he was telling me, they tried it out on a number of different bikes (I'm also assuming different types), and on every one they saw at least 2hp per cylinder when the electrode was directly facing the intake valve. On a CBR600 they saw 3.5 per cylinder!

I don't suppose you'd get those kind of numbers with a 400/4 or a CB750, but it's interesting that it would make such a difference in some motors. It can probably be partially attributed to the bikes probably all having high compression ratios.

Just thought I'd throw that out there!


Ben

[68grandprix]

Spark plug indexing will commonly see power gains in ineffecient combustion chambers. I assume the Cb750's are relatively ineffecient due to their age? I also know Briggs cart racers index their plugs. Jimmy.

[MRieck]

Just to add a couple cents:

The new mechanic at my local shop just graduated from AMI down in Florida and completed the dyno training as his last course. One of things they focused one was indexing spark plugs.

From what he was telling me, they tried it out on a number of different bikes (I'm also assuming different types), and on every one they saw at least 2hp per cylinder when the electrode was directly facing the intake valve. On a CBR600 they saw 3.5 per cylinder!

I don't suppose you'd get those kind of numbers with a 400/4 or a CB750, but it's interesting that it would make such a difference in some motors. It can probably be partially attributed to the bikes probably all having high compression ratios.

Just thought I'd throw that out there!


Ben

I don't want to start trouble but I find 3.5 HP increase per cylinder unbelievable . That is about a 14% increase in power from that 600 engine. I've built 600cc engines for roadracing and 14% involves alot of work. This would include really tightening the squish, pistons, headwork with a good valve job. Maybe, and I mean maybe, 3.5 total increase and I wonder if that was an STD figure on the dyno not actual. I also wonder if designer fuel was used.