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Team STG Racing
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337 Posts
The most common answer is, how fast are you? Not trying to be sarcastic, but most people will say that unless you are running in the top 10 or better of the 600cc/1000cc Expert classes, then race fuel is a waste of money.

With that being said, you can pour U4.4 in a stock bike and pick up some power. Obviously it would be better if the bike were tuned for it. But that is the beauty of U4.4, you can pour it in an otherwise stock bike and pick up a lil juice.

But at $70 per 5gal can, you have to ask yourself "am I not on the podium because I am short 5hp to the other guys?".
 

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Shell 93
 

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Premium Member
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30,470 Posts
93 pump gas. my bike is one of - if not the - fastest 600's around. the pilot, on the other hand... :(
 

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www.1seven1.com
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2,064 Posts
Miller has the AMA spec fuel on pump, so that's what my bike is tuned for. Sunoco GTX 98 octane unleaded. Fairly good stuff and about $7 a gallon. Also, I don't have to drain the gas like expensive U4.4 (but daaaamn does u4 smell good!)

Honestly, buy what's easiest. You can make up for 3 hp in one turn alone by getting on the gas earlier on corner exit. :D
 

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Parts Pimp
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26,455 Posts
The most common answer is, how fast are you? Not trying to be sarcastic, but most people will say that unless you are running in the top 10 or better of the 600cc/1000cc Expert classes, then race fuel is a waste of money.

With that being said, you can pour U4.4 in a stock bike and pick up some power. Obviously it would be better if the bike were tuned for it. But that is the beauty of U4.4, you can pour it in an otherwise stock bike and pick up a lil juice.

But at $70 per 5gal can, you have to ask yourself "am I not on the podium because I am short 5hp to the other guys?".
:stupic

VP MR12 is also good for a 3-4 ponies on a stock motor. Any oxygenated race fuel is gonna make more power due to the large increase in air in the motor. Ideally you wanna have a fuel controller to run a richer AFR with the oxygenated fuel.

The 100 octane from the sunoco race pumps is only gonna be beneficial on a high compression motor, or one running a lot of additional timing advance. It's not oxygenated.

I'd like to run race gas just to smell it all day. :laugh It's real rough on O2 sensors and fuel pumps tho. So if you do decide to run it OP, be sure to syphon out the extra fuel after you race. Don't leave it sitting in the tank for the fuel pumps sake. And if you can, eliminate your O2 or get ready to replace it every 50 hours or so. LOL
 

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n00b
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2,325 Posts
Stock bike would you run anything above 93? Unless you are having detonation issues their is no reason to run higher octane fuel. You won't get an increase in power unless you tune for it like chief said. It's a waste of money to run race fuel unless you need it.

On another note I can get Cam2 110octane at a local pump for $7/gallon and it's fun to run just for the smell lol.
 

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www.1seven1.com
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2,064 Posts
I'd like to run race gas just to smell it all day. :laugh
So true! My bike blows wicked blue flames on downshift with u4.4, as well. :laugh

With stock motor internals and tuned fuel and ignition, I get maybe 3-4 hp running the spec fuel. I do like the unleaded so the O2 sensors last longer.

I'll be buying MR12 for the RS125, but that's a whole different animal.

-D
 

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Team STG Racing
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337 Posts
It was previously mentioned, but just to clarify, octane simply refers to how resistant a fuel is to combustion. So running a higher octane, for the simple reason of doing so, is not going to result in more power.

If your motor isn't modded, have higher compression etc and is tuned to need higher octane, you aren't doing anything but lightening your wallet. Ideally, you want to run the lowest octane possible that you can get away with without pre-detonation.

There are race fuels out there that are only 87 octane.

Labeling 93 Octane "Premium" is one of the biggest marketing schemes ever because it leads uneducated peoople into thinking "only the best for my shit". 93 Octane isnt better, it is just different. If your bike is tuned for 87, then putting 93 in it accomplishes nothing.
 

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Team STG Racing
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337 Posts
My motors are built to where they can't run on pump gas, at all. I have a selectable map switch and I run U4.4 for practice and track days, then MR12 for races.

Then yes, at the end of the weekend, i siphon it out, put some pump gas i there and let it run till the exhaust doesnt smell like race fuel anymore.

But that is only if it is going to be more than a week or so. If im doing back to back weekends, i wont even bother. The U4.4 is much better than the U4.2 in that aspect...which was much better than the U4. They say you can leave the U4.4 in there and it wont hurt anything, but i still siphon it out just for peace of mind.
 

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Discussion Starter #11
Thanks for all the info. I'm a noob with this stuff and wanna hear this stuff from people with experience and a gained knowledge
 

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FastForward Performance
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961 Posts
I'll be buying MR12 for the RS125, but that's a whole different animal.

-D
Not a smart move at all. Unless you are running a low compression unleaded head 10.4cc or more your motor will be very unhappy along with your wallet. If you are going to run VP I would recommend C12, MRX01, or VP110. MR12 is not formulated for high compression 2 strokes. Q16 works really well at high elevations because of the O2 content, but I would not run at your location any lower than a 9.8 or 10.0 head.
 
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