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Engine and Transmission / NF Compression test figures.
« on: August 29, 2022, 06:13:19 pm »
Hi All.
Sorry for the length of posting but as a newbie I'm as ignorant as can be.
My newly acquired NF has developed a noise that at first I thought it was noisy tappet(s), but now suspect the "clacking" is lower down in the cylinder.
New to this wonderful old Militare and having only covered approx 250 miles since collecting the beast, today I decided to perform a compression test to try and diagnose whether it's piston ring(s) or valve guide(s) may be the culprit.
I understand that no engine likes to sit not run for long periods and these engines can be heavy on exhaust valve seat and guide
So......
The compression test results were:
Warm=60/65psi. For all three tests.
Warm with a shot of oil in the barrel=105/110psi for all three.
Seems a little extreme to me and on my other engines would suggest a broken or stuck ring, or very worn bore. But with less than 8K kms what would you far more experienced folk day?
It doesn't use oil that I can determine, but I haven't put enough miles on it as yet to know for sure. It does have smoke from the exhaust whilst idling and reving, but probably more black than blue! It does run rich. Better now the needle is on 2nd notch, but Spark plug very black.
So before I strip top end or do more damage riding it whilst weather lasts, I'm seeking advice.
I'm not looking to up the rather Conservative horse power, or make it something it wasn't designed to be. Making the head ready for E10 fuel wouldn't be a bad thing though. I'm using Valve master plus at the moment. Hope that hasn't been a reason for the smoke and noise?
Any help and comments most appreciated.
Sorry for the length of posting but as a newbie I'm as ignorant as can be.
My newly acquired NF has developed a noise that at first I thought it was noisy tappet(s), but now suspect the "clacking" is lower down in the cylinder.
New to this wonderful old Militare and having only covered approx 250 miles since collecting the beast, today I decided to perform a compression test to try and diagnose whether it's piston ring(s) or valve guide(s) may be the culprit.
I understand that no engine likes to sit not run for long periods and these engines can be heavy on exhaust valve seat and guide
So......
The compression test results were:
Warm=60/65psi. For all three tests.
Warm with a shot of oil in the barrel=105/110psi for all three.
Seems a little extreme to me and on my other engines would suggest a broken or stuck ring, or very worn bore. But with less than 8K kms what would you far more experienced folk day?
It doesn't use oil that I can determine, but I haven't put enough miles on it as yet to know for sure. It does have smoke from the exhaust whilst idling and reving, but probably more black than blue! It does run rich. Better now the needle is on 2nd notch, but Spark plug very black.
So before I strip top end or do more damage riding it whilst weather lasts, I'm seeking advice.
I'm not looking to up the rather Conservative horse power, or make it something it wasn't designed to be. Making the head ready for E10 fuel wouldn't be a bad thing though. I'm using Valve master plus at the moment. Hope that hasn't been a reason for the smoke and noise?
Any help and comments most appreciated.