19 cc domes, race gas?

[YFZ350kid]

stock stroke, stock bore motor running 19cc domes in a cool head, race gas or pump gas, the previous owner always ran VP C12 race gas and im thinking that may be a bit high, seems a mix or straight 100 octane would be better. Opinions, I do not have compression readings but as a rule of thumb, would 19cc domes on a stock cylinder require pump, 50/50, or full race?

[shanYE west]

stock stroke, stock bore motor running 19cc domes in a cool head, race gas or pump gas, the previous owner always ran VP C12 race gas and im thinking that may be a bit high, seems a mix or straight 100 octane would be better. Opinions, I do not have compression readings but as a rule of thumb, would 19cc domes on a stock cylinder require pump, 50/50, or full race?

Whats your elevation?

[Z0sick]

stock stroke, stock bore motor running 19cc domes in a cool head, race gas or pump gas, the previous owner always ran VP C12 race gas and im thinking that may be a bit high, seems a mix or straight 100 octane would be better. Opinions, I do not have compression readings but as a rule of thumb, would 19cc domes on a stock cylinder require pump, 50/50, or full race?

 

I run 19's in a cool head at an elevation of 1300ft. I have a max compression of 185psi. I also run +5 timing. For me, the added insurance of running 111 is worth it. It may run fine on 100, but what is a few extra bucks? The price difference here between 100 and 111 is $.65.

[YFZ350kid]

I run 19's in a cool head at an elevation of 1300ft. I have a max compression of 185psi. I also run +5 timing. For me, the added insurance of running 111 is worth it. It may run fine on 100, but what is a few extra bucks? The price difference here between 100 and 111 is $.65.

 

man, your fuel is cheep then, im in Las Vegas, and i can get 100 on the pump for $5.25, or a 5 gal jug of C12 for $65, basically $13/gallon.

 

I want to be setup to run at Dumont Dunes, so ill be riding between 800 ft to about 2000 feet here in lasvegas. re-jetting is no big deal to me so i can always change jets to the altitude.

 

Anyone in LasVegas, is there any place to get 110-115 octane on the pump in town, or is it just buy it by the barrel?

 

Whats your opinion on running E85 (approx 104-105 octane) in a banshee? good or bad?

[dajogejr]

We can all give you advice, however...no one can tell you without actual compression readings from your particular motor once you assemble it.

 

My guess would be mix 50/50 race/premium pump....but it's just that...a guess.

[YFZ350kid]

We can all give you advice, however...no one can tell you without actual compression readings from your particular motor once you assemble it.

 

My guess would be mix 50/50 race/premium pump....but it's just that...a guess.

 

 

ya, i understand that one, my old 1989 finally gave out, clutch grenaded, locked up tranny and blew a hole in the cases... so im trading it in on an 05 with only minor mods to it. ill see if i can get the compression readings before i leave the shop with it. anyway, thanks all.

[Snopczynski]

This is not something you can assume or guess on. Combination of dome size, base gasket thickness, squish, timing, and elevation all play a role in determining the octane you need. So, you need this info to determine what gas you need to run. Even a more stock motor can benefit from running 100 octane 50/50 race gas, it will run cooler. If you somehow ended up over 175-180 psi compression, or your squish is out of spec you can end up eating a piston as a result of not enough octane, or improper squish tolerances.