Compression Ratio for KZ1000?

Just a quick question guys: what is the compression ratio for a stock 77 kz1000?
Currently porting a head and the guy wants to know...

Thanks for the replies.

Steve
Auckland NZ

It's nice and high at 8.7:1 according to my OEM S/M published in 1981.

Later, Doug

Thanks Doug, I did a search in the database buy couldn't get the system to work. Appreciate that a lot. Cheers!

Steve

StreetfighterKz wrote: It's nice and high at 8.7:1 according to my OEM S/M published in 1981.

Later, Doug

I was surprised by this..who needs turbo pistons with this compression..lol.

What can one get away with increasing the compression with an oil cooler? 10:1? 11:1? Also happen to know the numbers it makes with higher compression?

I'm just curious.

An increase in compression alone, doesn't do much for you, maybe a couple of hp or so if you're still running pump gas. Compression increase, like most other mods, does not do a lot by itself, it needs to be combined with other mods.

Compression increase calculator by Bruce Bowling

.

Very interesting. So if I bump up the compression ratio on my KZ650-C1 from the stock 9.5 to 11 my peak hp will jump from 64 to 66. Certainly not much of a gain considering the costs and risks associated with boosting the compression ratio. This helps illustrate why the factory didn't bother with high compression ratios when the bikes were made. Ed

"This helps illustrate why the factory didn't bother with high compression ratios when the bikes were made. Ed "

That decision didn't have anything to to with HP, it was to make sure those things would run on whatever knocko-special gas you poured into them without pinging. Put a cam with more duration, and more displacement, and the increase in compression does a lot more for you.

Compression helps puts the "crispness" in the throttle response. That equates to better acceleration. I've run and built a lot of KZ street motors with 190 - 200 PSI on high test pump gas.

Squeeze is a good thing....as long as it's the right amount for the right application.....ask your girlfriend / wife if you don't believe me :silly:

Alot has to do with head design a more eff. head will
allow a higher c/r.
Look at a Gen 2 Busa or ZX14 their around 12 -14 to 1
and will live all day on ten pound's of boost with the right tune.

"..ask your girlfriend / wife if you don't believe me"

That's an advantage of having a sheep... no complaints

GPzEric wrote: "..ask your girlfriend / wife if you don't believe me"

That's an advantage of having a sheep... no complaints

:laugh:

zukdave wrote: Alot has to do with head design a more eff. head will
allow a higher c/r.
Look at a Gen 2 Busa or ZX14 their around 12 -14 to 1
and will live all day on ten pound's of boost with the right tune.

My Aprilia is at 13:1 and that little bugger has some serious bite to it. The throttle response and crispness of that engine is outrageous! Detonation isn't an issue unless you decide to use low octane piss fuel or run it lean.

It is never just one thing that will give you a lot of power other than boost or nitrous.
Compression adds crispness and response, removing excess weight from the bottom end adds more crispness and response, cams always help but really work well with some head work, and carbs make a huge difference once the head can flow enough to take advantage of it.
Power takes time and money. We all wish it was easy and free but it isn't!