What piston is this xr600

[litng1]

Ive got wiseco 4366P4 installed says its 40 over.What CC does this make my bike and how much compresion is it?Should I run 93 octane or is this not needed.Bike is all stock but with a superstrapp and KN and this piston with a 163 main jet.Thanks guys

[martinfan30]

Ive got wiseco 4366P4 installed says its 40 over.What CC does this make my bike and how much compresion is it?Should I run 93 octane or is this not needed.Bike is all stock but with a superstrapp and KN and this piston with a 163 main jet.Thanks guys

i would def. run supreme. dont know unless its in mm. 101 mm is 657cc, 102 mm is 653 cc 103 mm is 671.

[Beyond The Pale]

The stock piston is 97mm. .040 over is 98mm. That give you about 2% more displacement or 602cc up from the 591cc stock size.

Yes run 93 octane. The 4366 piston is the high compression one. If you run regular the engine will likely fry. Stock is 9:1 and your piston is 11:1. I get occasional pinging with premium in my stock compression bike.

[litng1]

Thanks guys.So would I be better to run some 110 mixed with 93? Is my main jet enough? I went from a 158 to a 163 and it picked up alot of power.I have a 165 and 168 Im going to try.Thanks again

[HawkGT]

As cleonard said, definitely run 93. I doubt I could run pump gas at all in my situation. But your's may be different.

My XR650R with it's stock 10:1 piston will knock just a touch on the crap 91 octane "boutique" fuel sold here in AZ. It has to be super hot outside (like 105+ degrees) and I have to put a serious load on it--but it will ping. The liquid cooled XR650R is apples to oranges compared to an XR600 though. I guess I bring it up just to point out that the particulars of the pump fuel in your area (beyond octane rating) can matter to a (relatively small) degree as does the conditions you ride in (this can matter a LOT).

I built TRX400EX (same engine as the XR400R and very similar to the XR600R, just smaller) with a 10.8:1 JE piston once. It would run on 91 but any kind of load and it would start knocking. Pretty much it was unrideable at anything but a put-put pace without at least a 50/50 mix of leaded race and pump. That experience is probably a lot more relevant to your XR600. But only relevant to a degree--I'd guess your riding is in lower temps, perhaps higher elevations, and almost certainly higher humidity---->all things that will suppress engine knock.

My advice for trying to figure out if you can get by on a certain fuel is to try it. Go find conditions that favor deto (as best you can)--low elevations, high engine temps, high air temps, low humidity, high engine loads, "best power" jetting (i.e. not rich), etc--and see if it knocks. Pulling a tall gear from lower RPM at WOT on pavement on a real hot day is what does it on my XR650R. If it knocks just a little under the worst of conditions then just having that awareness will probably be enough to get you by on that fuel. Slight knocking can usually be actively avoided by keeping the gas fresh and controlling engine load when knock is detected. If it knocks heavily under those conditions--or worse--knocks under less demanding conditions, than you know another fuel is needed.

$0.02