4-Stroke Fuel Injected Race Fuel

[KingpinsEx]

I have done some researching and it looks like VP U 4.2 is the best fuel to run in a high compression four stroke fuel injected quad. I am running a 13:1 compression piston and the U 4.2 sells for 15/gal (thats 75$ for 5 gal) and I was hoping I might be able to mix it with 93 pump gas. Only thing is I believe the U 4.2 is oxygenated and I'm not sure if that would be compatiable with pump gas. Just curious on what anyone else is running on a similar setup and would this work, either 1/2 and 1/2 or even 3/4 and 1/4? Also do I need to run a special spark plug with the higher compression motor?

[flyer15015]

Why not just run nonoxygenated Shell premium gas and throw in a bottle of 104 additive. Shell is 91 octane anyway.

[deathman53]

there is no way 91 will be good for 13:1 even with the booster, it doesn't work as good as claimed. On my 250r's I use 114 leaded sunoco cam 2, I get it for $10/gallon. I won't build another motor that uses race gas, its too expensive to ride and it can be hard to get.

[eastside 400]

C12 should work, car guys use it so it should be FI safe, im not sure about it tho, i cut my C12 50/50 with premium for 14+:1 comp

[KingpinsEx]

Ya I have heard of many guys running the C12 but they were on carb. machines. Prolly wouldn't hurt, I did run pump 93 on my stock compression piston and ran fine. There was an article in quad a while back that said the Yamaha techs were adamant about using U4.2 though. Not sure if this is the way to go or not. I race and want more power, but geez 15/gal is outrageous. :eek2: Thing is I need a new piston and can't see the sense in buying a stock compression, whats the highest you can go without race fuel?

[eastside 400]

12.5 typically, i would go with a 14:1 or so, bumping up just a little bit isnt very noticable and if your putting a piston in you might as well make it worth it, C12 isnt real expensive and when you cut it 50/50 with premium its not bad at all

[kfx400rider03]

idk where i can get vp fuel near me but a gas station 10 minutes from me has power mist 112 is that any good?

[KingpinsEx]

Originally posted by eastside 400
12.5 typically, i would go with a 14:1 or so, bumping up just a little bit isnt very noticable and if your putting a piston in you might as well make it worth it, C12 isnt real expensive and when you cut it 50/50 with premium its not bad at all

I have heard you only gain like 1 to 2 whp going from 12.1 to 13.1... Too me that is not worth it when you figure all the fuel that I go through in a season..

[motomxman450]

to save some money what you can do is have "practice gas" and "race gas" to put it in good perspective, just think you spent a good chunk of money on your motor so when racing why not get the most out of it? when practicing you can do with a cheaper solution. i would run the 4.2 strictly for race days, but when not in use make sure its in a sealed contaner or all the oxygas you bought is just wasted. when practiceing c12 mixed with 93 at 50/50 will be fine.if you have a hard time finding it go to the vp website and find the distribution chart, then get the number and give them a call they can tell you the closesest place that has ordered the gas around you...........................

[440exhondaman99]

all you guys are over talking all this.... i have a 12.1 piston and have a lil bit more then stock stroke and my bike dont even make a real 11.1 compresion ratio... your only going to have a true 12.1 or 13.1 ratio if you using a stock cam... im runing a 12.1 piston with a stage 2 cam and im looking at less a lil less then a 11.1 ratio... so i realy only need to run about a 96 octan.... anything more and its a waste of money and i will be losing power.... so you all need to learn a lil more about your motor and figure out what compresion ratio you realy have before wondering what fuel you need to use.... to much octan and you will lose power not gain...