Actually fuel injection has little to do with allowing you to run more compression on a particular grade of fuel....

The reason the YZF, Suzuki DRZ400 (both carbureted) and Cannondale are able to get away with such high compression ratio's is they run very wild, high overlap cams combined with well designed combustion chambers.

The high overlap cam allows some of the charge to escape, thereby lowering the effective compression ratio.

This is also why you don't see 12.5:1 fuel injected production cars. The automotive manufacturers can't get away with running high overlap, race style cams.

 

is it true that if you use race gas that you have to drain the tank of what you didn't use

 

No. Acutally just the opposite.

Race gas will last much longer than pump gas in a given container, so that's not a concern.

You want to minimize transfers from one container to another to avoid losing vapors. Draining your gas after every ride would be one of the worst things you could do.

 

The Cannondale runs on 93 octain thats what the owners manual says. I should know I own fx400 #14

 

first, gabe, it is good to hear from you, and as usual, you explained it. i was thinking is was something like that, but doubted it, because it kinda defeats having a high compression piston, except as a $$selling$$ point. hey canman, do you have any picks, and how does she run? (what did you pay?!) hope you have good luck with #14!

 

Actually it works really well. The compression stays right where it should be with the radical cam.

 

Well, are you going to give us a review then?

 

my XR250R is 11.5-1 stock and it runs on 85 octane well, just gives a knock or two when ya drop the clutch in hot weather

 

Hello #14. This is #5. Glad to see someone beside myself has a fx400 on this forum. What kind of riding are you going to do with yours. I'am trying a H/S race this weekend. Talk to you later.

RACERJIM

 

what color did you guys get? any problems croping up yet? and where they 8000 or did you get a deal? so where is the review?