VP U4.2 fuel??

[Pat E]

I just picked up my '10 YZ 450 and when asking the dealer about which race fuel to use, he said U4.2 but that it should be drained and not left in the bike. The pump gas sucks in my area, so that was never an option anyway, and frankly, if I can afford 10 grand for a bike, I can afford race gas. My question is, do I REALLY have to drain after each ride? How long can it sit in the bike without damage? Like most vet riders, I don't have the time to drain fuel all the time. I am not using race gas for performance, but for peace of mind. Is there another VP product I should be using or is the "don't leave it in the bike" thing just overblown? This is my first four-stroke ever, which is why I don't know. I ran straight C-12 in my two-strokes for years. Thanks.

[grayracer513]

U4 used to be really bad about gelling up in the carb when stored. The current version is U4.4, and may not be better in that regard, as I had heard that was something they were working on.

But U4.4 is pricey, and you simply don't need the octane it offers. MR12 could be just right for your situation. It has a motor octane of 90, which means the research octane would be around 98 at least, well over the 95 your bike requires, and it is not likely to need such cautious treatment as the old U4 did.

[Pat E]

Thanks! Not to sound dumb, but when you say the old U4 are you referring to the 4.2 or was there one before that? The dealer said it was the fact that it was so highly oxygenated that was what would mess things up if left in the bike. What is the time frame they are talking about? It's one thing to leave in the bike for months at a time but what if a ride 2-3 times a month and then drain for winter? I guess what I'm asking is what is too long to be left in bike?

[grayracer513]

In the beginning, there was U4. It would leave gel deposits in a carb in under a week. Then there was U4e (CA emissions), U4.2 (addressed gelling issue?), and now U4.4.

As I say, the original was impossible to leave in the bike for a week, or store in any plastic container. How the new stuff is about this, I haven't heard, but I will say it's been quite a while since I heard a "U4 killed my carb" horror story, too.

Probably your best info on this will come directly from calling or writing to VP. Google them: VP fuels.

[gfmoto]

If the bike is fuel injected how would the gas sit in the carb/throttle body at all?? Will it gel in the tank? I use to run 50/50 u4 to pump as my engine guy recommends and I left it in the tank but ran the carb dry.

[KJ790]

Like Grey said, a lot of people had gumming problems with the old U4, and U4e. I ran both of these, never drained my tank, and never had a problem for years on multiple bikes. I always added a little marvel mystery oil to the fuel, and to this day I always wonder if that played a role in keeping my carbs from gumming. U4.1 came out and I had terrible troubles with that, VP told me I was a liar and my issues were impossible, but 2 weeks later that was pulled from the market after some major problems occurred for some sponsored riders. U4.2 replaced that and seemed to be the answer, performance like U4 and U4e without a big of a gumming problem and less odor. I see that U4.4 is out now, and I am can't wait to get my hands on it to see what that is like.

U4.2 seems to be much better about gumming up carbs than it's predecessors. The problem with leaving it in your tank is that it's performance gain comes from the fact that it is oxygenated, and leaving it in a plastic gas tank or gas can causes the fuel to lose a lot of it's edge. If you want to keep the fuel performing it's best, keep it in a metal container in a cool place until you are ready to ride, then put it in your bike and ride.

[rickallen124]

According to my local shop they had some guys with heavily modded fuel injected quads that they told to run the U4.2 for the octane. A few months down the road these guys had issuses with the fuel eating the o-rings and destroying their fuel pumps. They have been selling just the vp red fuel since with no fuel issues in FI bikes/quads. The vp SEF(small engine fuel) looks interesting but it costs $100/5g.

[Ga426owner]

I used these fuels for years, with any of the "U... anything" VP fuel you will still need to drain it after each use. I do not care what anyone tells you, it will gum up carbs, injectors etc....if left in any cavity of carbs or FI systems. Some older U anything gas also had higher valvetrain wear associated with it.... ask ZipTy Racing.....The oxygenated fuel works great in 4strokes - great performance but higher maintenance. Never dilute this fuel with any pump gas - you ruin the performance and properties of the oxygenated fuel.

If you do not want to go through the procedure to drain after a day of riding/racing and do it properly, you are better off getting C-12 and mixing it up to 50/50 (I prefer 60/40) C-12 to Pump gas 91-93 octane....but now I drain this also...Why? Because all Race Gas must be stored in metal containers in order for it to stay at it's peak. A Plastic gas can will kill Race gas and is to only be used for daily/hourly storage. Hence, the reason not to leave race gas in your bike....

[moto278]

not to jack this thread or anything. but ive ran u4.2 for the last couple years. tries v113 for a short bit but didnt like it nd went bak to 4.2. is 4.4 that much better than the 4.2? wats the price difference?

[delmas]

U4 used to be really bad about gelling up in the carb when stored. The current version is U4.4, and may not be better in that regard, as I had heard that was something they were working on.

But U4.4 is pricey, and you simply don't need the octane it offers. MR12 could be just right for your situation. It has a motor octane of 90, which means the research octane would be around 98 at least, well over the 95 your bike requires, and it is not likely to need such cautious treatment as the old U4 did.

would this VP fuel MR-Pro4.1 need to be drained each time.

Is this what AMA runs in SX

Thanks

[Polar_Bus]

I just picked up my '10 YZ 450 and when asking the dealer about which race fuel to use, he said U4.2 but that it should be drained and not left in the bike. The pump gas sucks in my area, so that was never an option anyway, and frankly, if I can afford 10 grand for a bike, I can afford race gas. My question is, do I REALLY have to drain after each ride? How long can it sit in the bike without damage? Like most vet riders, I don't have the time to drain fuel all the time. I am not using race gas for performance, but for peace of mind. Is there another VP product I should be using or is the "don't leave it in the bike" thing just overblown? This is my first four-stroke ever, which is why I don't know. I ran straight C-12 in my two-strokes for years. Thanks.

Alls i've ever done is run 93 octain pump fuel with a splash of Startron to prevent the E10 fuel from skanking up my fuel system:

http://mystarbrite.com/startron//content/view/93/123/lang,en/

Been running this chemical in all 11 of my engines from my Harley to my weedwacker and everything in between with excellent results for the past 3 years. E10 is BAD, BAD, BAD when it is allowed to sit for extended periods of time.

[Shogren65]

I've had 4.2 and now 4.4 in my 10' for a couple of months now. I haven't noticed any issues as of yet. Always fires in a couple kicks. Once I get a free weekend I am going to run my buddy's LM1 and do some tuning to see where the A/F actually is with this fuel. So we'll see what happens

[Polar_Bus]

Just out of curiosity, and you guys running race fuel because your '10 actually needs this level of octain, or are you running race fuel in an attempt to negate fuel spoiling ?

[grayracer513]

Just out of curiosity, and you guys running race fuel because your '10 actually needs this level of octain, or are you running race fuel in an attempt to negate fuel spoiling ?

A third motivation would be a quest for the one to two horsepower a good race fuel can provide.

[Ga426owner]

A third motivation would be a quest for the one to two horsepower a good race fuel can provide.

this is the only motivation for spending a avg of $100.00 for 5gal.....

Delmas..... the MR PRo VP fuel is almost twice this price......get your walley out.

[Pat E]

I wanted to run race fuel for the consistency and peace of mind. I certainly don't need more horsepower. I'm gonna end up running pump fuel from a local busy gas station only cause' the VP is gonna be too difficult to obtain on a consistent basis. My local supplier doesn't carry it in bulk, so you have to order 2-3 weeks ahead of time AND it's an extra 10 bucks every time for the VP can, which is non-refundable and worthless. I was using C12 in my 2stoke, but they had it in stock, in bulk and I could just get my jug filled. Thanks to everyone for your input, but I'm sticking to pump gas for the convenience, not the cost. Oh well..... now, about an exhaust....

[FinchFan194]

Alls i've ever done is run 93 octain pump fuel with a splash of Startron to prevent the E10 fuel from skanking up my fuel system:

http://mystarbrite.com/startron//content/view/93/123/lang,en/

Been running this chemical in all 11 of my engines from my Harley to my weedwacker and everything in between with excellent results for the past 3 years. E10 is BAD, BAD, BAD when it is allowed to sit for extended periods of time.

Gray what do you think about this Startron stuff? They sell it at my local shop is it worth it?

[FinchFan194]

How does the lead in these fuels affect the valves in our bikes guys?

[grayracer513]

Gray what do you think about this Startron stuff? They sell it at my local shop is it worth it?

I'm not familiar with it.

How does the lead in these fuels affect the valves in our bikes guys?

It's subject to debate. Personally, as long as the fuel burns cleanly, I think the lead thing is a non-issue.

[FinchFan194]

Thanks Gray as I always I appreciate the info!