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Cylinder pressure opinions 5 years 4 months ago #22061

  • Daro
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Hi I have a question regarding cylinder pressure. I have measured it on hot engine and the way the manual states. My Kawa have approximately 46000 km now, valve clearance is with in the spec and the measuring tool was compered to calibrated gauge prior to measurement. After adding some oil to the cylinders the measured value was more about 0,4 to 0,8 bar to compare to the measurement with out oil. What you guys think? I know what the manual says, but I like to hear you objective opinion what you bikes cylinder pressure look like and if anything needs to be done on my one any time soon or not. The bike starts and ride with absolutely no problem, spark plugs are all nice tan color.

Thanks Darek











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Last edit: by Daro. Reason: I posted in wrong category. Sorry about that.

Cylinder pressure opinions 5 years 4 months ago #22062

  • Kawboy
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Absolutely normal. The "little bit" of oil you added is non compressible and will take up space in the combustion chamber and that acts like putting in higher compression pistons. The oil also minimizes the leakage between the piston rings, cylinder walls and the piston.

Everything's fine. Go ride the wheels off of it and be happy. Burning a tan color - Tells me you're not burning any oil to speak of. Lucky You !!

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Cylinder pressure opinions 5 years 4 months ago #22065

  • Daro
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Hi Kawboy, I was thinking about the compression thing already for longer time, and as I read the manual witch max compression rate at 11,7 bar I thought my 9,2 bar was not that much but than again the bike actually runs great. Regarding oil, there is some degree of consumption especially when riding on high reeves. Thanks for you reply.

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Cylinder pressure opinions 5 years 4 months ago #22066

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Daro wrote: Hi Kawboy, I was thinking about the compression thing already for longer time, and as I read the manual witch max compression rate at 11,7 bar I thought my 9,2 bar was not that much but than again the bike actually runs great. Regarding oil, there is some degree of consumption especially when riding on high reeves. Thanks for you reply.

Not sure where you found that spec. This is from the KZ1300 manual which is where the ZN1300 manual tells you to go for information regarding the cylinders , pistons and head.

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Cylinder pressure opinions 5 years 4 months ago #22071

  • Daro
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Hi Kawboy, the spec is from the same table you posted, I converted (119~171 psi) to 8,2~11,7 bar and 14psi to 0,96 bar. Its still with in the usable range but I just thought 9 bar was rather on the low side, also the difference between two cylinder which in my case is almost 0,9 bar, its nothing dramatic thou, but still a slight concern.

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Cylinder pressure opinions 5 years 4 months ago #22072

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Daro wrote: Hi Kawboy, the spec is from the same table you posted, I converted (119~171 psi) to 8,2~11,7 bar and 14psi to 0,96 bar. Its still with in the usable range but I just thought 9 bar was rather on the low side, also the difference between two cylinder which in my case is almost 0,9 bar, its nothing dramatic thou, but still a slight concern.

the ideal compression
We have to keep in mind that this is a service spec. As the engine wears cylinders will wear at the top and piston rings will wear and the ring gaps get bigger. Valves will transfer material from the valve seats to the valves and also out the exhaust so the seal on the valves will be less.At the same time as all this happens, ash and carbon deposits will build up on the piston and cylinder head which will affect compression readings. So every engine manufacturer will come up with a service limit and allow the engine to run in a certain design criteria. If the compression falls outside of this window, you should probably do something. Too high a compression, and you take the chance of detonation. Too low compression and the wear rate will exceed exponentially.
You're differential pressure between cylinders can probably be explained away with different build up of carbon between the 2 cylinders and I wouldn't get too worried about it.
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