Fuel octane for 250R's
 

I thinking about buying a 250R witha 265 powervalve, but the gas we get is like the lowest octane. COuld this motor run on regular pump gas or would I have to add octane booster??

Fuel octane for 250R's
 

What's the "lowest" you can get? The lowest octane here is 87. You can run it on this, just tune for it and don't bump your compression up.

Fuel octane for 250R's
 

I believe it is 87 also. But what is the biggest someone can go with the powervalve and still run 87 octane??

Fuel octane for 250R's
 

The powervalve changes your exhaust port size. Octane is required to run higher compression and avoid pre-detonation. Compression is what will require you to run high octane, not a power-valve. That said, I would think you could run 92 octane pump gas no-problem (unless you are running a thin head gasket or cool-head with high compression).

Fuel octane for 250R's
 

stock I run 93 octane 40 to 1 seems to be okay

Fuel octane for 250R's
 

more than likely, if you are buying this motor the builder did incorporate a thiner head gasket, aftermarket dome or some other method of making the bike faster. dont buy the horse if cant afford to feed it right. [img]i/expressions/face-icon-small-smile.gif[/img] i run a 50/50 mix of VP 110 and premium 91 (CA). It's nothing compared to the gas my truck consumes to and from the desert. [img]i/expressions/face-icon-small-smile.gif[/img]

Fuel octane for 250R's
 

there will be no head gasket at all it will be O-ringed get a low compression dome.

Fuel octane for 250R's
 

smarty pants!

Fuel octane for 250R's
 

Well it is not just the motor I am buying it is the bike. I was wrong about the powervalve, but it is a 265 National Curtis Sparks and it does have a cool dome. All we have here is the 87 octane. DOes anybody think that the 87 octane plus some octane boost will be ok??

Fuel octane for 250R's
 

heres my 2 cents,do a compression test on the bike...get a psi number.then find out which dome is in it.if its the 21 or 22 cc dome,your fu@ked, if not its the smaller dome you can always run the bigger to lower compression.87 octane is pretty low...compression better be around160-170 to run that in my opinion.mine kicks at 188 and i run 94 ,which i think is pretty close to being right.going by the builder metioned,im thinking its going to be pretty stout and around 190 or up.i bet it rips! feel free to ask ? if necessary,we are here to help.......... ps: octane booster is the biggest scam going(research it)"raises octane 2 full points",what that means is 2/10 of a number.eg:94 octane becomes 94.2=waste of money!if you need more octane research homebrewed octane boosters..toulene,etc. but be carefull some of this stuff is fu@kin dangerous(face shield,rubber gloves,etc) im out[img]i/expressions/face-icon-small-happy.gif[/img]