Timing vacum advance.

[lankeeyankee]

I am thinking about putting more NOS with my progressive timer expierment.
Along with that idea the timing needs to be retarded.

The question / questions are.

How many degrees does the timing get advanced as RPMS increase?
I am assuming that the timing is only advanced by vacuum?
Does the bike know what gear its in besides netruel or not?

I was thinking if the timing is only advanced by 1-2 degrees by an electronic controller than it can be switched off to retard the timing when the 2nd stage of NOS is activated.

If I cant control it by the controller I was also thinking of throwing in a electro vacum solenoid to shut the vac off to the controller tricking it to think its at idle when the NOS is activated,

Ohh yes I am aware that I can purchase commander for 300.00 to get timing curves, but thats the easy and expensive way out.

Am I even close. Hoping someone will know before I have to dig out the schematics and read.
Thnx

 

[Rusty McNeil]

I don't know about n2o but with boosted motors (I believe there is some correllation between n2o and F/I as it's mostly about air and combustion chamber pressure) on cars I've usually pulled about .5-.75 degrees of timing per psi of boost for a motor runnning around 10:1 compression, starting the retard at about 2 psi boost and linearly from there till full retard at max boost. I've been told that pulling that much timing is pretty aggresive and not totally needed, but I never roasted any pistons either.

With n2o I'm not sure tho' since it's usually hits all at once,

The bike doesn't know what gear it's in.

The vacuum advance is actually thinking it's at idle when it's seeing maximum vaccum, venting it to atmosphere is going to make it think you're at WOT. I would try to figure out a way to interupt the signal on the electric side to the TCI rather than the vaccum side of the sensor.

It sounds like your on to something for sure.

The Dyna 3000 is the only device I know of with timing curves, and unfortunatley the one made for the late model ignitions is not externally switchable (which really pissed me off, because that was one reason I wanted one, for n20), I've heard the one made for the early ignitions does have an external wire that can switch it into full retard mode but don't know that to be a fact.

Good luck,

Rusty