Compression test |
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StevieG
Senior Member Joined: 06 May 2018 Location: West Sussex Status: Offline Points: 138 |
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Posted: 25 May 2018 at 19:49 |
moto Guzzi V50II
What is the ideal compression for each cylinder? I’m showing 125psi on the right, 110psi on the left which seems to have a leaky head gasket.
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motopete
Senior Member Joined: 18 Aug 2015 Location: Notts Status: Offline Points: 532 |
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Not sure how much difference capacity will make to the reading, but my 750 measures 210 -220psi.
Compression ratio would be similar I'd think...
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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My V50/3 had a reading of 149 psi on each cylinder after lapping in all the valves and fitting new head gaskets.
I would worry if both cylinders read differently by any significant amount. Did you have throttle wide open when doing test as 110 seems low CHRIS |
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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StevieG
Senior Member Joined: 06 May 2018 Location: West Sussex Status: Offline Points: 138 |
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No, plugs out, just turning over.
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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with throttle wide open maximum reading should occur within 4 or 5 revolutions of cranking.
Mine responded well to lapping the valves in and upped the psi reading on each cylinder CHRIS |
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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StevieG
Senior Member Joined: 06 May 2018 Location: West Sussex Status: Offline Points: 138 |
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thanks!! Will do just that plus head gaskets. Hopefully that will fix things.
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c13pep
Senior Member Joined: 31 Aug 2017 Location: Doncaster Status: Offline Points: 2110 |
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Just make sure that you are doing the compression test correctly before you strip the heads otherwise you will not have a reference point for comparison once reassembled
I think the V50/2 has slightly higher compression than mine so would expect reading to be more than mine. CHRIS |
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you can`t have any fun in a straight line
Monza Honda CB77 project |
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Brian UK
Moderator Group Joined: 13 May 2014 Location: Surrey Status: Offline Points: 17641 |
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The important thing is the comparison between the pots. The engine should be hot, and throttle held wide open. If this was the case, then 110 seems low. Unless you have a head gasket chuffing, it's more likely one exhaust valve is pitted. A leak down test tells you more but it's more difficult to do.
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Brian.
Better 5 minutes late in this world than years early in the next. |
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GC888
Senior Member Joined: 21 Dec 2015 Location: Manchester UK Status: Offline Points: 174 |
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160 on my v35
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