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Discussion Starter #1
Does race gas do anything for a bike with a stock motor? People talk all the time about how stock bike only needs 87 octane, but is there anything special about race gas besides super high octane? I hear of racers with stock motors using it, but I don't really know why.

:-*
 

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rather than talk out of my ass and give you hearsay, I'll just say that the smell is intoxicating! I hope that tides you over till the racer's get here.
 

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avc8130 said:
Race gas is great...but generally speaking you want the compression to use it.
yeah, thats what I want to know, if it only benefits super-high compression motors
 

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High octane race gas will cause your bike to run worse not better if you don't have high enough compression. "Oxygenated" race gas (like VP-U4) can produce more power with a stock motor if you jet/remap for it.
 

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wonderjosh said:
yeah, thats what I want to know, if it only benefits super-high compression motors
most race gas that you'll find at the races isnt super high octace. like jarel said, its oxygenated fuels with relatively low motor octanes, somewhere between 94-97 for VP fuels like U4 and MR1. there are ingredients in the fuel that control the burn time and all that fancy stuff that regular petro doesnt have. but to answer your questions, you can pour it in a stock motor and it will definitely make more power.
 

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i've got a couple gallons of VP110 oxygenated unleaded in the sv. it's what i run in my turbo talon and i love it in my bike. runs incredibly smooth and power is great/smooth. Definitely needs remapped, but it's just one tank. I'd say this would be a great alternative to the u4/MR series.
 

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oh, and it's only $6.75/gallon 8)
 

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Race gas also burns a bit cooler. I know when the track temperature is over 100, our cars overheat less with race fuel vs plain premium pump gas.
 

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VP U4 on stock motor, mapped or jetted for it, can add 2 - 4 HP. Proven on a dyno, saw it with my own eyes. VP U4 run vs. the Pump 93 run.
 

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And if you leave U4 in you fuel tank for a day or two, you'll run the risk of gummed up carb jets and needle seats/fuel injectors, etc. The stuff evaporates incredibly fast and you can't leave it in the tank, it needs to be in an airtight container. Don't ask me how I know this....... ::)
 

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I'm a VP dealer, and have been selling and using race fuel for 5 years. VP has been putting warning lables on U4 and other oxygenated fuels they sell for about 6 months now. Some users have had problems, others have not, so it's a disclaimer on VPs part. If you use any type of oxygenated race fuel, you should run some pump gas through your system once you are done racing for the weekend. I've never had a gummed system, but I have had some corroding to the inside of my gas tank, when I left MR9 in there for a month after the end of last season.
U4 will give your stock bike a noticable boost just by pouring it in, have your bike jetted, or remapped, for even better results. Big compression, there's VP U2 which is higher octane. :)
 

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'generally speaking' how would you need to re-jet for race fuel? does it usually require bigger / smaller mains, clips on the needle, etc ??
 
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johnnySV said:
'generally speaking' how would you need to re-jet for race fuel? does it usually require bigger / smaller mains, clips on the needle, etc ??
you need to go richer since fuel is oxygenated.
 

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you can always crank up timing ifyou dont have the compression for race fuel.
 

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We have been using C12 or C14 in the SBK engines and U4/MR9 in the SS stuff with good results
 

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wonderjosh said:
Does race gas do anything for a bike with a stock motor? People talk all the time about how stock bike only needs 87 octane, but is there anything special about race gas besides super high octane? I hear of racers with stock motors using it, but I don't really know why.

:-*
Basically, there's 2 types of race gas. Oxygenated, usually with a moderate octane rating, and "normal" non-oxygenated, usually with a higher octane number. The oxygenated stuff will make a little more power without any other changes, and another bit more if the jetting/mapping is dialed in for it. The non-oxygenated type won't make any more power just by pouring it in, but the higher octane will let you run higher compression and/or more advance. It's biggest advantage in a SS motor, IMO, is that it's much more consistant than pump gas. Most parts of the country the pump gas varies a lot depending on the brand and the time of year. Typically more oxygenated in colder weather. Race gas is always the same, which minimizes the variables when jetting.
I've spent some time (and money ;D) on all three options, and would recommend pump gas in a stock motor unless you've got a specific problem that race gas will solve.
 

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I have a station near me that sells sunoco purple 110 octane race gas. I used it in my atv which is highly modded with increased compression, but did't really notice any difference, so I use 93 in it.
 

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I would appreciate any tips on dealing with race gas (U4) while at the track. I just picked up a race SV650 and the PO gave me 2 unused / unopened jugs of U4. I'm trying to figure out the logistics of using this stuff. Just pour it in, run all day, and then drain any remainder back into the jug at the end of the day? Then I need to run a little regular fuel through the carbs. Should I run it dry of the U4 first and then add some regular gas and then run it some more? What a pain it seems to use U4 :eek: :'(

Draining out of the SV seems to be a pain with the vacuum operated petcock. Seems if I put in a manual petcock (is there a drop in replacement?) and then put a T in the fuel line (with appropriate valve) through which to drain the tank and to fill the carbs with regular race gas.

Any tips would be appreciated since I haven't messed with this nasty race gas before...
 
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you prety much got it.just get hose with little pump on it and suck it out,run regular fuel through it and park bike.
I would not mess with petcock.
when it gets realy hot down there mix U4 and pump gas.
I dont run anything but pump gas,I dont see it worth hasle.I do have hp without it so it is not big deal to me.
you maybe have to run if compression is raised.
 
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