Octane rating for 810 motor?

I was wondering if anybody out there that was running an 810cc kit in there 650 could tell me what octane fuel they have been using... and in particular if they are using an oil cooler?

I am asking because I am building a similar motor... want to run without a cooler if possible.

Would like to know if I should try and drop my static compression ratio... right now at 9.9:1 and I can alter that pretty easy.

I don't mind running premium gas if that's what it will take.

You should use premium in the compression that this motor is supposed to have.

I have mine built, but have not run it yet so I can't give you concrete info. But I'm going to be using an oil cooler, I just think its a good way to protect our investment.

I run premium and a oil cooler.

Mark

Thanks Mark.

I ran almost the same combo with a cooler back in 1990...

I am again running those same pistons but they have been modified by lowering the dome and bigger valve pockets than in 1990. I must have been about 11:1 then, but never really bothered to CC anything - just stuck it in and ran it!

I just CC'd them with the head I am going to use which has the valve seats sunk and de-shrouded.

Pistons are old MTC 831cc units, current combo has ported head with stock valves flowing 25% more air than stock, Andrews 20 cams, and VM26 carbs from a KZ1000. Going to run stock air box and dual exhaust.

I don't want to run a cooler because I want it to look stock - I am not going to put a ton of miles on it... it's going to be a Saturday Nite Special.

I am in Canada, so it is a bit cooler here.

I was pretty sure I could get by on 91 octane and if it pings I will try and find some 94 or use some booster... just could not remember what I was running back then!

10:1 is normally ok on the kz900 motors, i dont see why this would be any dif. the only thing that would be an issue would be the extra heat and small duration cams.
i run 91 on my 1200cc bike so u should be fine. if u have a ping u could try a cooler then.
u could run a tighter squish to improve the burn and help prevent stagnation at the outer edge of the cyl. Also make sure u massage any sharp edges from those pistons and there valve pockets.
does the 650 run a shell main bearing or a needle?

Bearing shells, the big motors (900 and up) are the only ones with roller bearings (don't know about the Z2 though).

u can run .040" squish on a kz900 with rollers. a kz with shells should be able to run even tighter.