103 Engine compression help
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3rd Gear
Joined: Aug 2014
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From: Earth
103 Engine compression help
Hey I need some help finding the correct PSI reading when doing a compression test on a 2012 wide glide with a stock unmodified 103 engine. Anybody know what it is? All the searching I've done here and other places has only given me PSI readings on modified engines. Not a stock 103.
Thanks in advance for any help
Thanks in advance for any help
HDF Community Team
Joined: Jun 2006
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From: san antonio
Actually, the CCP in a stock 103 should be about 195psi (sea level); if above sea level that would need to be adjusted down. The number will vary a bit from motor to motor depending on the condition of the top end, actual chamber volume and deck height but it shouldn't vary much.
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3rd Gear
Joined: Aug 2014
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From: Earth
Thank You . Can you tell me where you heard 195 psi was the correct pressure? IdahoHacker's post is showing 125 psi as coming from the service manual. Is your number another figure from the manual? Maybe the highest reading the bike should show? The more I search this topic the more confused I get,LOL.
Club Member
Joined: Jul 2014
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From: Idaho
The service manual says a minimum of 125, with no more than 10% variation between the two, is normal.
The service manual is all about whether or not the bike needs service. So, if both cylinders are 130, no engine work would be considered necessary.
That's not the same as what compression you would see in a brand new engine.
The service manual is all about whether or not the bike needs service. So, if both cylinders are 130, no engine work would be considered necessary.
That's not the same as what compression you would see in a brand new engine.
HDF Community Team
Joined: Jun 2006
Posts: 12,763
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From: san antonio
Thank You . Can you tell me where you heard 195 psi was the correct pressure? IdahoHacker's post is showing 125 psi as coming from the service manual. Is your number another figure from the manual? Maybe the highest reading the bike should show? The more I search this topic the more confused I get,LOL.
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HDF Community Team
Joined: Jun 2006
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From: san antonio
All you need to know to get in the ball park is displacement (bore/stroke), head gasket thickness, chamber volume and dome volume. Use the defaults for chamber and dome volume for a stock motor; you can ignore deck height. Use the OEM head gasket thickness and 30* for the intake valve close as the OEM cam for a '12 model is not in the cam selection list. Adjust for sea level and you have it.