The compression ratio on the 400EX is 9:1. The Raptor is 9.2:1. The Z400 is 11.3:1!!! I know a car wont run that much without racing fuel...how does this quad manage? Anyone at sea-level having problems running 91 or 92 octane in it?
Thanks,
Fish

 

technology my friend...don't ya just love it? All these bike are meant to run on pump gas, I have seen a running difference on all with racing castor and octane booster(blendzall)

BRAAAP

 

up to 11.5:1 is ok to use premium with, after that you are getting a high posibilty of early detonation without race gas

 

The reason for the high compression is to compensate for valve overlap. What happens is the exhaust valve starts to open while the intake valve is still open, bleeding off some of your compression. The reason why they do this is at high rpms you want the valves open as long as possible. HAVE FUN & RIDE ON!

 

P.S. Badfordman here again....The Z400 only requires 87 octane.

 

I always run 93 in mine and have had NO problems at all! (Except when I got thrown and got blood on the brain! But I DON'T think it was the gas' fault! hmmm....maybe I could sue TEXACO!? lol)

 

For the average Z400 rider pump gas works fine. I would use what it calls for in the owners Manuel and any more than that is up to you.

Chet

 

They get away with the higher static compression ratio by the valve overlap (bleeds some compression at lower RPM's and the combustion chamber design (the biggest reason).

 

Two other things help the Z get away with its high compression.
(1) There is a jet streem of oil shot at the under side of the piston that keeps it a little cooler.
(2) The metallurgy relationships between the piston, cylinder wall, and head are specialy designed to help eliminate detonation.
But as we all keep hearing from the know it alls, the Z is just a 400ex with yellow raptor plastic, so none of this could have possibly been Suzuki's idea.[img]i/expressions/face-icon-small-wink.gif[/img]
LMAO

 

lol...im sure noone here cares, but the 400EX requires 91 octane...
just my 2 cents.