Tuning on the edge with C-12

[hoosierf]

Rich, I have a question. I have a Powroll stroker motor in my DRZ125L. I mated a 24mm carb to it and it is jetted right on the edge. If my wife rides it, the plug is perfect, even on sand tracks. When I jump on it all is good until I burn about 10 laps chasing the 80 riders around then it develops a slight bog. I haven't noticed any detonation, but the plug reads lean. I'm currently running C-12. Is there another fuel that would bump me just a little closer to the rich side? I'm being lazy and trying to avoid constantly changing jets since we both ride the bike. I thought you once mentioned AV gas as a good choice when you are tuning on the edge because it remains in a liquid state as it enters the combustion chamber. I'm wondering about a blend of 25% AV gas and C-12?

Let me have it.

 

[MikeS]

The AV gas may add some cooling but it can cause it to get lean because for the same volume of fuel some of it will stay liquid and not burn. C12 and even MR2 can be rich when compared to AV gas or pump because they vaporise more and burn more completely. You may just want to bump the main 1 size as you seem to be on it all the time. Your wife may not spend much time on the main jet so the effect of the richer main may never be felt or noticed by her.

Rich is better at the 4 strokes and may have a secret to share :)

 

[jmics19067]

I like the main jet idea if she barely runs on it and you are constantly on it but here is a couple of other thoughts I have
are you sure it is running lean for you or is the plug just running hot?

You MIGHT be able to get away with just a colder plug for when you ride.

or you can jet rich enough for your riding and then run a hotter plug for your wife if fouling happens to her. If you are close for here would she even notice the difference?

it is backwards thinking performance wise but I guess you could jet for an an oxygenated fuel<mr2?> for when your wife rides and then cut it with c12 for when you ride. I say backwards because it seems kinda strange to give a person who is not aggrasive a fuel with more performance ability and then cut the fuel down for some who would probably appreciate the performance more.

 

[motometal]

wow...i can't even GET oxygenated fuel locally here (for any reasonable price anyway),&nbsp; I'm gealous!