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Ignition help requested

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Post Fri Dec 09, 2011 6:46 am

Posts: 2
Location: Grenoble - France


This is my first post and I need your help and experience for my bike.
I am in France so, please be indulgent with my so bad English.

I am the happy owner of an S&S 100SB with a Keihin FCR 41 race carburetor and a Dynatek 2Ki ignition module and I have no VOES

This engine is very powerful and have a lot of torque, it's pussing hard...

I have a little trouble at idle and only at idle. The rpm is varying between 900 and 1300 when the engine is hot. I think there not enough ignition advance because when I turn clockwise the ignition module, the rpm is more steady.
I try to change the curve but if I put more advance the engine is pigging when I turn the throttle.

Do you think I have to put a VOES, Ultimate engine have no VOES but they have no square engine like the SB100.

Does anybody Have the same engine and would like to share the engine curve?

Any comments and experience would be appreciated.

Thanks so much for your help.


Post Sat Dec 10, 2011 7:56 am

Posts: 1642
Location: Interlaken, NY USA

I don't have any experience with the S&S engine you have, but here's my opinion anyway :lol:
I would hook up the VOES and reset your timing accordingly. As you probably already know, the VOES will allow you to run more advance overall, and then it will retard it when under low vacuum conditions, i.e, under hard load, to avoid detonation.
I've looked into electronic ignitions alot for use on Frankenstein for just this reason.
I haven't done it yet just because the modules are kinda pricey.
As for curves, generally speaking, try to give it as much advance as soon as you can, and let the VOES help with too much advance under load.
I'm thinking some dyno time would be the most effective way. With pipes, compression, cam, gearing, etc, what works for others might not be the absolute best for you. But searching other web boards/sites might give you some ideas.
Sounds like fun, I'd like to be doing similar experimentation myself on my own machine.

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