Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice


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Tamresnier
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Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice

Post by Tamresnier »



Hello everyone,

I recently replaced the valves on the right side cylinders of my engine, but now I have some concerns regarding compression. After the valve replacement, the right-side cylinders consistently show higher compression compared to the left side . Difference is about 20 psi. Unfortunately, I used handheld diy tester and just pressed didn't have precise measurement tools, so exact data is unavailable, but I know there are difference

Could anyone shed light on whether this compression difference could pose any significant issues? I've become worried, especially because after the valve replacement, I've been hearing detonation at lowering from high RPMs.

Is it possible that detonation is related to these compression differences? I would greatly appreciate any insights or advice!

Best regards,

Rein


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Rambozo
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Re: Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice

Post by Rambozo »

Do a leakdown test if possible. More than likely you have valve leakage on the left.
What was the reason for the right side valve replacements?
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Tamresnier
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Re: Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice

Post by Tamresnier »

Hello!
The reason of replacing was bended valves.
You can read about it here

viewtopic.php?f=6&t=70243
Rambozo wrote: Fri Sep 01, 2023 10:59 pm Do a leakdown test if possible. More than likely you have valve leakage on the left.
What was the reason for the right side valve replacements?
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Re: Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice

Post by Rambozo »

Ok, I would expect slightly higher compression with a fresh valve job on the right. 20 psi difference is not a big deal, but it might not idle quite as smooth. If it bothers you, you can do the left side valve job. Detonation doesn't happen during deceleration. But vacuum leaks can cause popping during decel. Check all the vacuum hoses as they are often cracked on a bike this old. The good thing it is an easy fix.
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Tamresnier
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Re: Compression Discrepancy After Replacing Right-Side Valves - Seeking Advice

Post by Tamresnier »

Thank you for that reply!
I did find one loose hose.
Just made a post about it here:

viewtopic.php?p=418668#p418668

I would be grateful if you could take a moment to review this post. Maybe you have some knowledge about it that you could share with me.

R.

Rambozo wrote: Sat Sep 02, 2023 1:50 am Ok, I would expect slightly higher compression with a fresh valve job on the right. 20 psi difference is not a big deal, but it might not idle quite as smooth. If it bothers you, you can do the left side valve job. Detonation doesn't happen during deceleration. But vacuum leaks can cause popping during decel. Check all the vacuum hoses as they are often cracked on a bike this old. The good thing it is an easy fix.


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