if you jet for ultimate 4,what do you use for practice?

i was thinking of running ultimate 4 in my 03 cr450 to get more hp on race day , i know some say you need to rejet and some say you dont. but lets say you get it spot on with u4 what will happen when i go back to regular 93 octane pump gas? how hard is it to rejet. i have raced years with four strokes and never once touched the jetting. would it be worth the work of rejeting each time. cause of course i cant afford to practice with u4. also this might be a really dumb question but what do you do with the 5 gallon vp gas can when its empty, do they return them or do you just throw them away(that would seem really wastefull)

I run the same jetting with U4 and pump between practice and race days. I was happy with the jetting in both cases. If anything, I run a little richer with the pump fuel. I run the U4 50/50 with pump. Hope this helps.

I'd keep the can and find a shop that carries a drum of the U4. We are constantly looking for steel cans to refill because we buy the U4 in 30 gal drums.

This may be a dumb question, but can you mix the U4 with regular gas or do you have to empty the tank to switch between them.

Thanks.

This may be a dumb question, but can you mix the U4 with regular gas or do you have to empty the tank to switch between them.

Thanks.

Not a dumb question. You can mix them. Actually on my 450 (that's for sale) I never saw better benefits from running straight U4. I always mixed. And yes I jetted properly for it. On my 250F though I run it straight.

As for what I do on practice days? I rejet and go back to pump. I have it down to be able to rejet the bike so quick I dont really care.

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