VPU4

[MELK-MAN]

never had any issues leaving the U4 in my 2000F4, never ever..HP gain?? how about 5hp.
here is the map with pump gas, and an "after" on U4 with jetting and 4deg timing advance.
REALLY woke the bike up.

[Super Dave]

Ack!  

Is that the kind of dyno sheet you should really get one where the first run is decent.  

Ouch...  Doesn't look like it carbureted well from the get go...prolly had less of a gain than 5HP...

And Greg...I saw you on the grid for one of the FUSA races...I was walking by, I waved...but you have no idea what I look like...LOL!

[davegsxrold929r]

Ack!  

Is that the kind of dyno sheet you should really get one where the first run is decent.  

Ouch...  Doesn't look like it carbureted well from the get go...prolly had less of a gain than 5HP...

And Greg...I saw you on the grid for one of the FUSA races...I was walking by, I waved...but you have no idea what I look like...LOL!

oh he did...  ;D :o   LOL.......

[MELK-MAN]

Ack!  

Is that the kind of dyno sheet you should really get one where the first run is decent.  

Ouch...  Doesn't look like it carbureted well from the get go...prolly had less of a gain than 5HP...

And Greg...I saw you on the grid for one of the FUSA races...I was walking by, I waved...but you have no idea what I look like...LOL!

Hey Dave. Nope.. I have seen your bike, was doing well in the FUSA race running about 16th. After the restart i crashed between T1-2 when a rider went around me and i hit his rear wheel.

The first run on the F4 was after a 2-brothers pipe, but yes, pre jetting. The bike did run stronger on top pre jetting and U4 but the midrange sucked. You could feel the drop. It made about 93 hp pre pipe, and about what you see after pipe (95+) then 101+ after jetting and U4 and timing advance..

[tug296]

When I run U4 in the stock 99 VTR with just cans, it has a noticable increase in power.

[L8brake731]

Remember what the absolute purpose for using "race fuel"is for: obtaining HP.
If you choose the wrong fuel, thinking that octane will equal hp, you might be in for a BIG surprise. You say you are planing on burning this in your R6; well all I can add is that if you your compression ration is less than 12:1, I would'nt venture into the octane numbers above 100 rm/2. Octane slows down the fuel mixture burn rate, causes in longer push so to speak after ignition is introduced. If you don't have the compression to burn the mixture through the entire stroke, you will only be losing hp.
On the other side, you asked about U-4. It is a highly oxygenated fuel. Kind of like giving you an artificial compression boost. As U-4 burns, it creates O2, and causes a volume change. Due to U-4's vapor pressure and distillation curve, it has been known to cause "vapor lock" on hot arid days on bikes that recirculate or just have high tank temps.
I run U-4 in my SV and have a 3.5 hp gain on the dyno. The curve is pretty linear, but more prevelant at 8k rpm. So far, I have had no problems with "vapor lock" but I do keep my fuel iced on hot days. If you think you can change the characteristics on race fuel by mixing it with "pump" fuel, be careful as you can easily screw up the "cocktail" and end up with some pretty expensive, nice smelling pump gas.
The choice in race fuel is a critical on especially at $10+ a gallon.

[L8brake731]

Ok, now I know what "thingy" is...
The male chicken ;D

It was meant to read: "Male Chickentail" above!

[speedster_1]

On my 954, From a custom map w/ 93 to another custom map w/ U4 I only got 2.5hp up top.  A touch more in the mid range.  U4 is 92 oct.

[Super Dave]

Remember what the absolute purpose for using "race fuel"is for: obtaining HP.

Unless you're looking to accelerate better.  Then we're back to fuel again.

How long are you at top RPM's?  But how long are you at lower RPM's?  If one can gain acceleration exiting a corner...

Octane is irrelevant.

It's all about chemical.

Use what's in your budget to get the best acceleration.  It might be high or low octane.  Many of the commonly available pump race fuels that one might consider to be high octane don't work well straight in multicylinder motorcycle engines.  Others can be different.  

It's hard to completely generalize on racing fuel if you haven't used everything.