Race fuel and jetting

avizpls

avizpls

#11-A
I have a carburetor-fueled bike which runs merely OK on pump gas. I have upped the compression....but mostly I want to get away from methanol on this bike.

I think I want to use Sunoco's 110octane Leaded fuel.

I have a few questions and I cant tell from researching online who knows what.

1) Is it OK to leave this stuff in the gas tank like regular fuel. Its non-oxygenated. I would think its not a problem, but who knows.

2) should I plan on running leaner or richer than with pump gas?

3) with the higher octane, I believe I will be advancing the ignition timing, correct? any thoughts on how much? (1-3 deg, 5-10 deg....)

Any other thoughts/suggestions?
 
avizpls

avizpls

#11-A
well, I'll open it semi-regularly to fill up a portable container, but will reseal it. Im not sure if it is a plastic or metal drum yet. I hope for metal.
 
JonnyZ!

JonnyZ!

New Member
Sunoco 110 will keep. Certainly keep sealed when stored. Oxygenated stuff "spoils" over time

110 octane doesn't burn hotter or faster than lower octane fuel but has greater resistance to preignition (detonation). Higher RPM,compression etc increases combustion heat substantially and can lead to preignition/dieseling with regular pump fuels/alcohol enhanced. High octane fuels are very stable and have a predictable flame front on ignition.

You may be able to go a pinch leaner in that the stable burn will allow a higher state of tune with this fuel but If you were jetted correctly before, there should be no need to rejet.
Most bikes will handle some ignition advance but i would forgo any advance on the timing especially if you've upped the compression. Your plug burn will give you a good indication of whether your timing is correct. The electrode burn is the tell but the plugs should be new and would require a plug chop. Once base timing is established I would leave it alone and let the ECU do it's job. As the bike stands right now, I would just gas and run. Your start up and throttle response will be much improved with that big twin.
 
avizpls

avizpls

#11-A
Thanks for the tips!

The bike is a 1994 Carbie. There is no 'ECU' per-say and there is no feedback (O2 sensors, TPS etc) except for the RPM. The ignition module is a stand-alone programmable unit.

Either way, I'm comfortable now to run it as-is and see how it runs.
 
JonnyZ!

JonnyZ!

New Member
avizpls;177985 wrote: Thanks for the tips!

The bike is a 1994 Carbie. There is no 'ECU' per-say and there is no feedback (O2 sensors, TPS etc) except for the RPM. The ignition module is a stand-alone programmable unit.

Either way, I'm comfortable now to run it as-is and see how it runs.
Click to expand...
Oooooooo

Stand alone would require quite a bit of work to set up initially. The fact that it's already based and running is a good thing. Again ....gas and go. It should do just fine.


What, may I ask, are you runnin???:cool:
 
avizpls

avizpls

#11-A
002L.jpg


Its true, the stand-alone did take quite a bit of fiddlin with to get it running to where it is now.

Somethin a little like that. Its a 1994 Ducati Monster 900cc underneath all of that extra skin.

Hi compression pistons with a drastic lightening of the engine components. The ignition is an Ignitek unit out of Netherlands or something like that. Pretty simple. Takes the pulses from the coil pickups, and spits out a pulse for your coil packs based on a programmable curve.

I'd like to point out that it has since undergone a much needed improvement of the tank and tail section :)
 
dlockhart5x

dlockhart5x

New Member
good ole sunoco purple is a nice clean leaded fuel, no major tuning required
it is also a decent substitute for VP C12
we are looking at getting a barrel ourselves because pump is getting worse
 
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