Is race fuel worth it for 4 strokes?

[Rubblemaker]

I'm considering switching from pump gas to VP's Ultimate 4 race fuel in my '03 CRF 450. While talking to a VP dealer, he informed me that I would need to go up probably 2 main jet sizes when I switch.

My first question is for those of you who run race gas, is it a noticable difference, considering it's $10.75/gal? Secondly, did you need to make the above mentioned jetting changes?

Just a note, I ride at an altitude of about 5,500 feet.

 

[Ray3667]

I have run Race gas on a few occasions. I have found no measurable(seat of pants) gains. but I do live and ride at 7500ft +...

 

[Patman]

Yes I run VP fuels in all our bikes. I don't know that the seat of the pants difference is huge but the bikes are more crisp and consistant, this was especially true when I ran VP MR2 in my Montesa 315R and in my XR284 which gets VP U4. Yes I did need to fatten the brass in the carbs a bit and am still messing with my son's CR85 because it's just not quite right yet.

 

[a454elk]

Put this in the back of your mind as well, when done riding and if you won't be riding anytime soon, clear out the race gas, it'll gum up the carb, please! Yes, I learned my lesson the hard way, wasn't worth it to me, don't need no race gas to beat Texans like Twinny and Thump.

 

[Patman]

Yeah Carlo but your running that tofu pump stuff.

 

[wornknobby]

well i find it wierd that some of you guy's needed to fatten up the brass alittle, because i have my cr jetted perfect for vp and when i could use any thing but 93 from the pump, my jetting was still dead on. why is this?

 

[cr lover]

i have a 04 crf 450 and i run tt111 race gas 106 octain mixed with 92 octain pump gas 50/50 at 1300 sea level do i neet to go up on my main ?it seems to run fine with no backfiring.

 

[Okiewan]

fatten the brass in the carbs a bit

Oh.. you sexsay tuner you! Nuttin better than fat brass, lol!!!

 

[Patman]

Oh.. you sexsay tuner you! Nuttin better than fat brass, lol!!!

that's me :fft:

besides unlike Okie, Patman can't afford the 24K gold carb parts, but atleast you gots the fat brass. ;)

 

[a454elk]

Fat brass rocks. I like BIG BRASS and I don't know why...

 

[slideways11]

Hey Patman are you running the stock carb on your XR284??

 

[Rich Rohrich]

Yes, Pat currently has the stock carb on his XR284.

 

[highmileage]

Patman has stated that he was thinking of trying of new carb. Will it be Mikuni flat side, Keihnin FCR, or Edelbrock? Rich I know your watching...Is there any hope with the stocker if line bored to say 33mm?