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Discussion Starter #1
I have sent a question to some dealers:
"Could you please send information about zx6r (09-12) engine compression rate dependent on head gasket thickness (0.6; 0.55; 0.50; 0.45)
What thickness gasket is safe to install without damaging the valves ?"

Received answers:
1. Kawasaki Ireland
"The thickness of the Gasket will have no effect on the valves, it will only make changes to the Pre ignition and the Detonation when the engine fires"
2. Thank you for contacting Kawasaki Motors UK.
Unfortunately the factory does not list the change of compression ratios when installing the Kit/different size cylinder heads gaskets. The main purpose of adjusting the head gasket thickness would be to achieve the correct Squish clearance. Once achieved you would then check the piston to valve clearance and if required adjust the valve timing as necessary.


Unless you have the relevant knowledge and equipment to carry out the necessary measurements, then i would recommend staying with the standard head gasket thickness. Many of our supported race teams run the standard cylinder head gasket.
3. Kent cams UK (company making supersport cams)
Hi
We don’t have a recommended gasket thickness.
Regards

So what is your opinion guys.
Is it good idea to install supersport cams (made by Kentcams UK) and 0,45 head gasket ? What ocate will be neccesary. Will i not blow my engine? :) Rev limiter will not be pushed up.
 

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There is a nice article in the latest edition (10/2013) of Roadracing World about setting squish; they talk about the effects, concerns and benefits of different gasket thickness.
 

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I have sent a question to some dealers:
"Could you please send information about zx6r (09-12) engine compression rate dependent on head gasket thickness (0.6; 0.55; 0.50; 0.45)
What thickness gasket is safe to install without damaging the valves ?"

Received answers:
1. Kawasaki Ireland
"The thickness of the Gasket will have no effect on the valves, it will only make changes to the Pre ignition and the Detonation when the engine fires"
2. Thank you for contacting Kawasaki Motors UK.
Unfortunately the factory does not list the change of compression ratios when installing the Kit/different size cylinder heads gaskets. The main purpose of adjusting the head gasket thickness would be to achieve the correct Squish clearance. Once achieved you would then check the piston to valve clearance and if required adjust the valve timing as necessary.


Unless you have the relevant knowledge and equipment to carry out the necessary measurements, then i would recommend staying with the standard head gasket thickness. Many of our supported race teams run the standard cylinder head gasket.
3. Kent cams UK (company making supersport cams)
Hi
We don’t have a recommended gasket thickness.
Regards

So what is your opinion guys.
Is it good idea to install supersport cams (made by Kentcams UK) and 0,45 head gasket ? What ocate will be neccesary. Will i not blow my engine? :) Rev limiter will not be pushed up.

I can figure it out if you know what the combustion chamber volume is

You can damage engine if the gasket is too thin with a stock set up, keep that in mind. Valve clearance is a big deal

Heres an article to help you out

http://www.racingheadservice.com/rhs/piston-to-valve-clearance-guide/
 

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Discussion Starter #5
Ok. as I see piston to valve clearance should not be a problem with 0,45 gasket.
What about octane ? will not 98 octane petrol detonate ? Local dyno guy said he will able to control combustion of 98 octane petrol up to ~13,8 compression rate.
 

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I ♥ Cute Cats!
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Depending on the geometry of the piston, the squish, etc. it's a little difficult to just say, "Use this octane with this compression ratio". Within a certain range you can usually extrapolate how a change in compression ratio will affect a cylinder, but you still need 2 data points :p Anyways I made this graphic a while back demonstrating spark-hook testing an engine:


Octane gives you a sort of buffer before detonation. So if you are using a lower octane fuel and can't realize the maximum power by advancing ignition timing, you can at least retard the timing so the engine won't detonate. A lot of forced induction engines do this so you can put lower octane fuel in, have a respectable daily driver, and at the track you can put higher octane fuel in, and it will advance the timing to where maximum power is. That and to cover their asses a lot of OEM's will design their spark timing maps conservatively anticipating that people might not use the correct octane fuel for their bike. So most supersports on the market say to fill up with 89 AKI octane fuel, but they CAN make more power if the timing is advanced and slightly higher octane fuels are used.

And by you saying "Petrol" and saying 98 octane I'm guessing you are not in the U.S. so I'll warn you that a lot of the people on KF from the U.S. might give you skewed advice on the octane portion. In the U.S. octane is an average rating of MON and RON rating systems. In the U.K. it's RON only. So in the U.S. 98 RON is really (98 RON + 88 MON)/2 = 93 octane (AKI = Average Knock Index).
 

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Discussion Starter #8
I have ordered 0,45 gasket, as soon as possible will take out the cams and will send to "kentcams", firstly my collarbone have to heal :)))
will update in a few months :)
 

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The Indifference Engine
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You can't (shouldn't) just slap a new gasket on there and pray. You need to measure the squish before you pull it apart. Check the stock gasket and determine what size you can run. A small change in head gasket thickness can have valve meet piston.
 

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You can't (shouldn't) just slap a new gasket on there and pray. You need to measure the squish before you pull it apart. Check the stock gasket and determine what size you can run. A small change in head gasket thickness can have valve meet piston.
this..

my bike will likely have a ss motor next year, Are you in the USA or in a diff country?? and i could have sworn there was a kit head gasket when the kit parts were out. Most that i will have build will just mill & deck the head most likely
 

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Discussion Starter #11
I am from EU. Still waiting for a gasket... and still did not send cams to remake.
But I do not worry about clearance...dealer confirmed there should not problem only by changed gasket. I will not grid the head... anyway i will check the clearance with clay.
Can't wait to try it... Have you done something to your engine already ?
 

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The Indifference Engine
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You really need to use plasti-gauge to make sure you're not going to tap a piston into a valve.
 

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Discussion Starter #13
All dealers I have requested do not have head gasket (0.45mm) it is backordered but nobody know when it will be in stock.
Do anybody have idea where can I get 0,45mm head gasket.
 

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What about butt dyno? Some people claim it's not hp but delivery.
 

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Gained 2hp, woohoo that was worth...
its not just the peak hp where you see gains, the midrange and length of midrange change is where the gains are at.
 
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