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I know there are many variables and I don't know what internals are in my JD but can anyone tell me the normal compression rates for the JD? Mine started running bad and when checked I got 25 psi out of the rear cylinder and only 15 psi out of the front cylinder.
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Sounds very low. You should have at least 75 psi. Confirm your guage accuracy. -
My racer, runs about 55 to 60 lbs warm, with an original iron piston/rings and tapered bore, since I built it about 5 year ago. Try lapping the valves, and the intake housing.Last edited by dlm32; 08-19-2016, 07:42 AM.David Morrill
Sylacauga, AL. USA.
AMCA #15284
Deadly Dave's Blog
Sharing the Lost Stories of Early American Motorcycling.
http://dlmracing.blogspot.com/
1921 Harley-Davidson Model J Racer
It will break a hundred, if you drop it from a plane!Comment
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