Ignition Timing

[C George]

For those who didn't see it under " Racing The KDX "

I bumped the timing " roughly a notch width past factory advanced setting " on my son's 200
that I've been complaining about for a while and did that make a difference.

I honestly think it just complements the other mods on this bike and a completely stock bike
may not respond the same way.

A small change but a BIG difference.

[Jaguar]

I make a performance CDI for the KDX and I can tell you that the stock one uses resistors with +/- 5% values, and capacitors with +/- 10% values. At what RPM the timing curve starts to retard depends in part on its resistance of 1264 ohms and capacitance of 4.7uf. So if the resistance is at +5% and the capacitance at +10% one RC time constant is 6.9uSec. And if the resistance is at -5% and the capacitance at -10% then one time constant is 5.1uSec which is 26% less than the maximum 6.9uSec. That is too big a variation. How that translates to real life: That results in a variance of as much as 1050 RPM for when the retard curve starts to kick in according to the original CDI's resistor and capacitor true values. The later the curve kicks in the more the peak timing advance will be which is great for low RPM power but terrible for high RPM power (because the KDX is too advanced anyway at top RPM). This explains the biggest difference between two new KDX bikes, just due to variations in CDI. Of course my CDI uses 1% resistors and 5% capacitors for less variation between CDIs, and it is adjustable.

[C George]

So your going to send me one to try ,,,,, ha ha

Seriously , We've raced electric scale cars for over twenty years and I completely understand
what your saying about mass produced parts. Bean counters usually win.

[C George]

One thing I didn't mention is that you have to be running a high enough
octane fuel to do this.

I mix our fuel to a true US rating of 95.

Both bikes also run compression of 180 +/-