VP Fuel


28 replies to this topic
  • TGettier

Posted May 14, 2007 - 11:30 AM

#1

Thinking of running some VP fuel in my 2006 YZ450f. I've been running Cam2 114. I've heard some mix 50/50 with pump gas. Any feedback on the type of VP and or blend would be helpful.

  • grayracer513

Posted May 14, 2007 - 11:59 AM

#2

First, understand that you DO NOT need and higher octane number than that provided by pump premium. Nothing will be gained by that other than a lighter wallet.

Secondly, a well matched fuel for a modern four-stroke, such as VP U4, will produce as much as two full hp over pump fuel BUT you'll need to rejet for it. You will also have to do some extra maintenance to use it. You'll need to drain the complete fuel system after each ride.

IMO, blending race gas with pump gas is like mixing ice cream with dog poop; the result somehow always has a stronger resemblance to dog poop than ice cream at most any ratio.

What you may want to consider instead, is buying some Toluene and adding it at about 15-20% of your fuel mix. It's much cheaper than blending race fuel, but you'll still need to jet up a little.

  • flintlock28

Posted May 14, 2007 - 02:37 PM

#3

From what I've read, the newer VP U4.1, is suppossed to yield a greater power output than U4, and also DOESN'T need to be drained from the fuel system, to prevent gumming up.

My bike runs great on BP 93 pump gas, and the way gas prices are climbing, I don't need to run anything more expensive. The VP will generally be more consistent than pump gas.

  • YamahaThumper

Posted May 14, 2007 - 03:55 PM

#4

Hey gray, what does the Toulene do once mixed with the gas? And whats the outcome?

  • grayracer513

Posted May 14, 2007 - 04:27 PM

#5

It will actually boost octane a little, but since that's unnecessary, that's not the point. It adds power. How much is an open question, but it does add some. Toluene is already a component of gasoline anyway. You'd just be adjusting the ratio.

  • YamahaThumper

Posted May 14, 2007 - 04:37 PM

#6

Gotcha, so jetting wise what would I need to be doing? Going down on the main? And I can just pick this up at the hardware store right? One more lol, does it eat plastics and rubbers like everyone says, or is it just when its in a concentrated form?

  • CaptainKnobby

Posted May 14, 2007 - 04:43 PM

#7

Maybe you can answer this question gray. I get my race fuel at Mark4 honda which is a motorcycle shop. The question is>>>> I dont know what kind it is,I asked one of the guys that worked there and they said they thought it was cam 2 but wasnt sure. It has a purpleish color to it and and drys pretty quick when you get some on your hand. Do you know what kind it would be?

  • YamahaThumper

Posted May 14, 2007 - 04:48 PM

#8

Theres no way in hell to be able to tell what kind of gas that is. Race gas comes in so many different colors. On a side note, I think torco is a purpelish color?

  • CaptainKnobby

Posted May 14, 2007 - 05:02 PM

#9

Well Ive been deciding on switching back to 93 pump gas but the only reason I have'nt is because the race gas burns so much cleaner. When I had a 05 yz 250 two stroker and when it came time to change the piston, on pump gas the top of the piston had a whole lot of carbon on it,and when I ran race gas it was real clean on top. Whether this is good or not thats the only reason Iam using it is because it burns cleaner. Is this a real reason to use the race gas or am I just wasteing money on buying it?

  • Maximus83

Posted May 15, 2007 - 03:57 AM

#10

Gotcha, so jetting wise what would I need to be doing? Going down on the main? And I can just pick this up at the hardware store right? One more lol, does it eat plastics and rubbers like everyone says, or is it just when its in a concentrated form?


Yea, I'd like to know too, when switching to Race Fuel, what is a typical rejetting? Down on the main like Yamaha thumper asked?

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  • OUCR250R

Posted May 15, 2007 - 05:08 AM

#11

From what I've read, the newer VP U4.1, is suppossed to yield a greater power output than U4, and also DOESN'T need to be drained from the fuel system, to prevent gumming up.


The new U4.1 has been discontinued. They were having SEVERE problems with it. It was making the bikes run WAAAY too lean, not to mention it smelled like burning trash compared to the U-4 smell. It also did not make as much power as the old U-4. They have gone back to the old U-4 for the time being. They are currently working on re-formulating the fuel.

  • Stripes123

Posted May 15, 2007 - 06:45 AM

#12

The new U4.1 has been discontinued. They were having SEVERE problems with it. It was making the bikes run WAAAY too lean, not to mention it smelled like burning trash compared to the U-4 smell. It also did not make as much power as the old U-4. They have gone back to the old U-4 for the time being. They are currently working on re-formulating the fuel.


I hadn't heard about U4.1 being discontinued so thanks for the heads up. I can say that the old U4 smells like perfume to me :applause:

The best way to rejet is on a dyno. My limited experience indicated that U4 requires much richer settings to obtain full benefit.

The elements used to add oxegenation in the fuel will evaporate through a plastic tank over a couple weeks. Go ahead and leave it in the tank if you don't care about power gain but if that was the case, why buy the stuff in the first place?

  • OUCR250R

Posted May 15, 2007 - 09:58 AM

#13

Yeah you definitely need to drain it out of the bike when you are done riding. And NEVER and I mean NEVER EVER leave it in the carb. You will be sorry you did.

  • Ga426owner

Posted May 15, 2007 - 01:28 PM

#14

Even if you drain U4 after each use - it can still gum up the carb.
My realWorld VP story:

I was very anal about doing this after years of using nothing but straight VP U4 and recently had to rebuild my carb due to either VP changing something in U4's formulation or a bad batch. I talked to ZipTy Racing who has tested U4 and almost every form of race gas and they told me they saw premature valve seat/guide wear from U4 and they stopped using it altogether. They recommended C12 with a 50/50 blend with Prem gas. I bought 5gal to try and almost have gone through all of it. It works great but I am not sure what HP benefit it will give if any, but it burns very clean. I was excited to hear VP's releasing of U4.1 but when they did this around the time of Bike Week - in Daytona this year it was not good at all. Several teams tried it at the Daytona 200 with disasterous results.....Jetting was near impossible and bike motors blew apart....so VP recalled/discontinued U4.1. I am glad I did not try it. If they come out with a new formulation of "U.....whatever" oxygenated fuel, I will try it once the real world testing is done. U4 was a great gas in the years I used it for producing more HP than any other 4Stroke specific fuel....yes you can tell the difference night and day to pump premium gas....but the flip side of gummed up carbs and constant draining made it too high maintenance for me......as well as the cost several years ago was around $40 bucks for 5 gal that now is $80+ bucks for 5 gal.
C12 is still cheap compared to U4 and has worked well for me thus far.....as if I need race gas anyway....:applause:

  • TGettier

Posted May 15, 2007 - 02:06 PM

#15

Thank to all for the feedback. I did go to the VP Fuel website and it appears that they have come out with a new version U-4.2 Specs from the website are as follows:

http://www.vpracingf....html#specialty

  • Maximus83

Posted May 15, 2007 - 03:29 PM

#16

I found recently that a Shell station near by sells 110 Race fuel. It said on the pump Race Fuel - Leaded. How does this stuff compare to the U4 and C12? Where can you buy these two fuels?

  • 642MX

Posted May 15, 2007 - 04:01 PM

#17

Here is why I use race fuel. I run a 13.5:1 piston, jetting is much easier with a leaded race fuel, my top end is squeaky clean from the lead, I believe the lead helps cushion the valve seats, its always the same everytime I buy it, and it smells great.

With that said, I use Monster 110 leaded race fuel. Its only $6.00/gallon so it not a huge expense to use it.

  • grayracer513

Posted May 15, 2007 - 04:11 PM

#18

Gotcha, so jetting wise what would I need to be doing? Going down on the main? And I can just pick this up at the hardware store right? One more lol, does it eat plastics and rubbers like everyone says, or is it just when its in a concentrated form?

Up on the main jet for toluene. Straight up, it will dissolve a number of things. It's the primary solvent in model airplane plastic cement. But in solution it seems reasonably safe. As I said, it's in gasoline already, and it's about 10% of U4.

  • 4literranger485

Posted May 15, 2007 - 07:46 PM

#19

you should be glad you can get 93 octane! in california i can only get 91 octane pee water, and i bet i pay a LOT more for it haha:cry:

  • CaptainKnobby

Posted May 15, 2007 - 08:00 PM

#20

I found out what kind of fuel I was getting from the motorcycle shop>>>> It was CAM2 which is 114 octane and is $6.00 a gallon. Is this a pretty good ok fuel to run or would I be better off to just use 93 octane from the pump and save money. I ran the cam 2 in my 2 stroke and the piston was always clean on top.





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