Who uses race gas

[Mikelehmann]

was wonder which gas you guys with the CRF450 run high test pump or race gas?

[Yardpro393]

unless you have significantly upped the compression or are running lean jetting, you're wasting your $$.

ultimate 4 is the only fuel to show a HP gain.

[MXCOP]

Three of my riding buddies have CRF 450's. Two run Amoco 93 exclusively and the third guy runs the Ultimate 4. The third guy put a big bore kit on the 450 or 480 as it is now. He also owns the local gas station that sells Ultimate 4 and is the only one of us that can afford it at $8 per gallon. He does say that he could tell a difference from the Ultimate 4 vs. 93 pump gas. I believe one of the old issues of Motorcross Action had the Ultimate 4 giving the CRF 450 a 4-6 HP gain over stock. Sorry so lengthy but hope it helps.

[madcow393]

only riders in the B and Money classes will need bikes moded out enough to use race gas. but if yo do have a porting job and higher comperssion you need to get it.

[Woody_393]

Chevron Pump 91 here. To be honest, I could never stomach the price of race gas.

[Blitz393]

Originally posted by Woody_CRF
Chevron Pump 91 here. To be honest, I could never stomach the price of race gas.

who says that pump gas is cheap??? ::

i remember when it was 85 cents a gallon. and my parents remember my grandfather complaining about the price going up to .25/gallon...


:

oh and i run pump 91-92 octane, depends on the station i go to.

[Woody_393]

Uh why don't you compare it to race gas prices and then lets talk again.

[MILAN]

Just curious, has anyone tried using an octane booster that you can buy from an auto parts store. I use 91 octane in my truck and I added some of this last week to one tank just to see if there was a difference and there was a noticable difference. It was like $2 a can and the can treats up to 20 gallons of gas.

[MATTXR250R]

I use 93 octane pump gas

[MILAN]

91 pump gas is the highest you can get in So Cal.

[Mikelehmann]

i only ask because the 450 have what? 12 to 1. try running that compression in a car with pump gas and its good bye motor

[Mikelehmann]

looking at honda web page shows the CR250F with 13 to1 12.9 for those that are picky no way will pump gas support that compresstion

[Blitz393]

lol woody i was just reminiscing.... 2 freaking bucks for 87 octane regular.... its BS :

[KTM250rm393]

My understanding is its very bad to add octane boosters to smaller engines. Its does something to the internals of the engine. Now this may just be for two strokes, but I've been warned by many NOT TO USE IT.

[Ranger_450F]

I run 92 pump gas,

Alot of the stuff I have read is that the race gas gives the rider a much cleaner burning fuel. Which in turn equates to a consistant jetting for that particular bike. I have not heard that it brings up the HP significantly so if that whats your shooting for then I think your wasting money.

[mxxx rrrider]

I have heard that at least some octane boosters will really discolor your tank

[Mikelehmann]

race gas will add a little power too any bike car because the beter qulity of the fuel. which has nothing to do with its octane. not much mind you. and why do motorcycle people always talk about VP gas CAM2 is never mentioned 110 octane and is much cheaper than VP

[Yardpro393]

is cam 2 the avgas?

[Yardpro393]

also,
the higher the octaine the slower the foel burns, and the harder it is to ignite. the oxygenated fuels are the only fuels that add Hp. high octaine fuels can actually lower performance of stock bikes

[Woody_393]

Just to add to what YP said.

The higher octane burns slower (which he said) which is why you need it on high compression engines with lots of motorwork. The octane rating of gasoline tells you how much the fuel can be compressed before it spontaneously ignites. Octane ratings have little to nothing to do with increased HP. Race gas (as already stated) can lead to cleaner jetting etc bacause it is much more consistent then what we buy at the pump, which in turn leads to more power, but only because the jetting is better. Octane can actually make you bike slower (if it doesn't need it) because it burns too cool (aka too slow).

What happens is the extra heat produced by the higher compression causes the gas to spontaneously ignite (like in a diesel.. well sort of since theirs is a controlled spontaneous) and higher octane stops this from happening. So if your ride isn't knocking/pinging you don't need it.

In all reality if you can get by with 87 octane and it doesn't ping than your fine, and are waisting your money on the higher octane fuels. I believe the higher you are ASL also helps eliminate pinging (which is why in UT you can't get more than 91 at the pump. We also have 85 at the pump and most places don't have that low).

The other thing to remember is that if say you run Texaco Unleaded 91 and your bike pings, try a different brand of gas. The way octane from a pump is calculated is from taking to octane figures (RON and MON) and dividing them by 2 (so ron + mon / 2). The RON rating (or the way they calculate it) was produced in 1928 on a slow running engine and isn't very accurate for higher rpm engines (like our bikes). The MON figure is more modern and much more accurate for todays applications. As a general rule Mon is always going to be less than Ron

Okay so here is my point to the last paragraph. lets say we wanted 90 octane fuel (just for sake of easy math). An oil refinery could take some fuel with a ron rating of 100 and a Mon rating of 80 to get 90. While others could be ron 95 and mon 85. Does that makes sense?

So if the gas you run is causing the dreaded Knock, switch gas stations and see if it goes away.