Engine Compression
Engine Compression
I have finally found that the compression on a twin cam should be around 190, is this right? I have been trying to track down a pinging issue and did a compression test. Front cylinder is 175 and rear is 208. What could cause such a high compression in the rear and low in the front? The bike runs well if you ignore the pinging, and we did do the test when the bike was warm if that matters.
2010 FLHX
screamin eagle stage 2 103 kit
big bore cylinders
big bore flat top pistons and rings
SE-255 cams
stage I air cleaner kit with one-piece back plate
heavy duty clutch spring
thunder header 2 - 1 - 2 exhaust
2010 FLHX
screamin eagle stage 2 103 kit
big bore cylinders
big bore flat top pistons and rings
SE-255 cams
stage I air cleaner kit with one-piece back plate
heavy duty clutch spring
thunder header 2 - 1 - 2 exhaust
HDF Community Team
Joined: Jun 2006
Posts: 12,776
Likes: 2,607
From: san antonio
Assuming heads are stock and OEM head gasket has been used, I would be doing a leak down test on the front cylinder. CCP on both should be near 200psi with your configuration.
You failed to mention fuel management and tuning or how you ride the bike. If the motor hasn't been dyno tuned, that could solve the pining issue. Also, down shifting and keeping rpms up at a reasonable level will help as well. Some consider anything under 2500rpms as lugging; not good for the motor.
You failed to mention fuel management and tuning or how you ride the bike. If the motor hasn't been dyno tuned, that could solve the pining issue. Also, down shifting and keeping rpms up at a reasonable level will help as well. Some consider anything under 2500rpms as lugging; not good for the motor.
Assuming heads are stock and OEM head gasket has been used, I would be doing a leak down test on the front cylinder. CCP on both should be near 200psi with your configuration.
You failed to mention fuel management and tuning or how you ride the bike. If the motor hasn't been dyno tuned, that could solve the pining issue. Also, down shifting and keeping rpms up at a reasonable level will help as well. Some consider anything under 2500rpms as lugging; not good for the motor.
You failed to mention fuel management and tuning or how you ride the bike. If the motor hasn't been dyno tuned, that could solve the pining issue. Also, down shifting and keeping rpms up at a reasonable level will help as well. Some consider anything under 2500rpms as lugging; not good for the motor.
HDF Community Team
Joined: Jun 2006
Posts: 12,776
Likes: 2,607
From: san antonio
sespt is what I'm using. has not been dyno tuned, I don't think that will fix this issue. I have been doing smart tune runs to adjust ve tables and have fattened up the whole fuel table when not in smart tune mode. Pinging happens worse in the higher rpms, but not quite as bad when the temps are in the 60* range.
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gnirtsnod
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Nov 12, 2011 09:33 PM
