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CB77 cylinder compression

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tom1104
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Posts: 9
Joined: Sat Jun 15, 2024 10:26 am

CB77 cylinder compression

Post by tom1104 » Sun Aug 11, 2024 9:30 am

Hello all,
I've just checked the compression on my CB77 and it's a bit lower than the spec thats mentioned online at around 150psi.
Mine read around 130psi is this still a good compression, what would be considered low compression for these cylinders
Thanks
Tom

tom1104
honda305.com Member
Posts: 9
Joined: Sat Jun 15, 2024 10:26 am

Re: CB77 cylinder compression

Post by tom1104 » Sun Aug 11, 2024 12:46 pm

Did another check and it seems I have 149psi on the left cylinder and then roughly 135psi on the right cylinder

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sky.fred
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Re: CB77 cylinder compression

Post by sky.fred » Mon Aug 12, 2024 12:50 am

If your measurements are different from the first time, you may have taken the wrong compressions, or your equipment may be unreliable.
To be optimum, compression should be done with the engine warm and the throttle open to allow air to enter the cylinders.
If compression is low, you need to put a little oil in the cylinder through the spark plug hole. If the compression is higher, the leak is in the piston rings. If it remains the same, the problem is in the valves.

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