Topic: Fine tuning

[bwaller]

Two requests for advice please, and never mind if you consider it wasting my time. It won't be the first time!

1) Plug indexing washers. I need to find some 0.75mm or so thick. By the way an inner valve spring washer from a 500/550 is a perfect fit @.5mm. I bought a set from Sudco...they're useless, three sizes, two of which are too thick.

2) Plug gap. We've all seen problem plugs fire in "still air" only to fail in the chamber under compression. With this in mind @ 12:1CR should I be thinking about running stock gaps? Has anyone done work to prove this one way or other. (Mike suggested I run the D9's no more than 0.032") I will be trying Iridiums on the dyno to compare.

Thanks

[turboguzzi]

1) stop wasting your time...  

2) been running forever the stock gap the plugs come with. only time i tried bigger gap got misfire..... not very scientific i know and you can blame my lousy GSXR coils but if stock gap works, why mess with it?

[bwaller]

This is the response I expected....you guys are all party poopers! 

I need to eek out every little ounce to keep up this year. I'm just trying to do some homework before I run it on the dyno again.

1) stop wasting your time...  

2) been running forever the stock gap the plugs come with. only time i tried bigger gap got misfire..... not very scientific i know and you can blame my lousy GSXR coils but if stock gap works, why mess with it?

[Darvill Racing]

Have you considered Spark Plug Indexing...?

There is a lot of debate and scepticism to whether or not spark plug indexing is worth the effort.
Some studies have shown 1-2% of total engine power can be lost through poor spark direction. Perhaps that does not sound like enough power to be concerned about, but consider this: Chances are that you, like the majority of us, have spent a fair amount of money on hotter coils, ignition boxes, better plugs, ignition wires, cap and rotor, and the list goes on. In fact many heads these days boast "revised spark plug angles" and "fast burn" chambers.
Heck, you probably even made the extra effort to set all your plug gaps to the exact specification. Well if you believe all those things make a difference, and they probably do, than it is only logical to think that the spark needs to face the right direction in the combustion chamber!

#justsaying

[bwaller]

Thanks Alex, that's part of my original question. I'm looking for .75mm washers to help with indexing.

When I built the thing originally I wasn't convinced there was anything to gain from indexing plugs in such a small chamber, (500/550) so I ignored it. When I reassembled the engine recently & checked, no two plugs faced the same way, so what the hell... it's not hard to do and if it doesn't help at least I feel better.  It sure can't hurt. If it goes well on "dyno day" I may try turning all the plugs to face the exhaust valve for comparison.

[Darvill Racing]

LOL...
I was speed reading, must learn to slow down (yeah right)... mind is in overdrive over the idea of a SOHC endurance bike using the billet block.
 

Ive noticed that no two mass produced plugs are the same, i buy bulk and spend time marking these (permanent marker line that is in line with the electrode gap), then take my time to wind these in one at a time until i find a matching set, i am not too critical with a tolerance of about 15% (either way) just so i am sure that the plug is facing towards the exhaust port.

[turboguzzi]

can i throw a spanner in the works?

assuming that you really knew the exact direction of mixture turbulence considering squish, swirl and tumble effects, would you be able to say what's the "best" orientation for the plug?

unless you do dyno runs, rotating ALL the plugs by 15 degs every time, dont think youll ever know what is realy the best orientation, gut feeling is not good enough

[bwaller]

Oh man TG, like I said....party pooper. 

Of course you're right or at least being logical. I think I'll try a couple different orientations when on the dyno anyway, then right or wrong, I'll put the idea to rest.

[Darvill Racing]

Oh man TG, like I said....party pooper. 

Of course you're right or at least being logical. I think I'll try a couple different orientations when on the dyno anyway, then right or wrong, I'll put the idea to rest.

You wont know until you try....

I was first introduced to this by a sprinter, he literally tried EVERYTHING and was convinced of the benefits. He was looking at a system in the USA that used a laser to ignite the fuel, it created multiple 'sparks' in the cylinder to give an even burn..... i wonder what ever happened to this system (shame i lost contact with him).

I have tried this on a number of machines and believe that it helps but your dyno runs could prove this (one way or another).

[iomtt9]

Hi Brent ... for what its worth, i've been using Nippon Denso plugs for 5 years now, never had a problem with them ( probably spoke to soon) They are Nippon Denso X31 ES-ZU. 25 thou gap.
Col

[Sam Green Racing]

Brent, have a word with Murphy about Iridium plugs, they can make a big diference.

Sam.

[bwaller]

Colin & Sam, I've been using NGK D9's and they are just the right heat range. However Mike & I are bartering, a cam for a set of ND Iridiums. We shall see. 

[scottly]

If you get the chance to do a dyno test with wider plug gaps, I would be very interested in hearing the results. I've just finished putting over 650 road miles on my bike with gaps set @ .045". (Gerex ignition) The bike ran great, and I still averaged over 50 MPG, even with a switch from 40 to 45 low speed jets in the Webers.

[Howell]

W

Hi Brent ... for what its worth, i've been using Nippon Denso plugs for 5 years now, never had a problem with them ( probably spoke to soon) They are Nippon Denso X31 ES-ZU. 25 thou gap.
Col

With our Gerrit Lether tuned Honda's we use the Race ND IXU01-31 IRIDIUM PLUG , expensive but worth the money.
http://www.sparkplugs.co.uk/pages/database/plug-detail-ccp.asp?partno=IXU01-31