Engine Compression
#1
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
#2
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.
#3
Sounds like the cams are off 1 tooth.
30 lbs difference is what we've seen when that type of scenario is brought in for repairs.
Scott
30 lbs difference is what we've seen when that type of scenario is brought in for repairs.
Scott
__________________
HILLSIDE MOTORCYCLE & MACHINE, INC.
HARLEY-DAVIDSON SPEED & SERVICE CENTER
5225 SOUTH MAIN ST., MUNNSVILLE, N.Y. 13409
Sales/Support 315-495-6650
www.hillsidecycle.com
Walk-in Retail Showroom
Complete H-D Machine Shop
Case & cylinder boring
Complete Cylinder Head Shop
High-Performance Engine Kits
Crank Rebuilding
Direct Link & PowerVision Tuning
Goodson HD Tooling Manufacturer
Maxton Mile World Record
4500 sq ft. facility
OVER 35 YEARS OF H-D ENGINE BUILDING.
See us on Facebook.
HILLSIDE MOTORCYCLE & MACHINE, INC.
HARLEY-DAVIDSON SPEED & SERVICE CENTER
5225 SOUTH MAIN ST., MUNNSVILLE, N.Y. 13409
Sales/Support 315-495-6650
www.hillsidecycle.com
Walk-in Retail Showroom
Complete H-D Machine Shop
Case & cylinder boring
Complete Cylinder Head Shop
High-Performance Engine Kits
Crank Rebuilding
Direct Link & PowerVision Tuning
Goodson HD Tooling Manufacturer
Maxton Mile World Record
4500 sq ft. facility
OVER 35 YEARS OF H-D ENGINE BUILDING.
See us on Facebook.
The following users liked this post:
Jeckel (08-16-2016)
#4
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.
#5
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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