I have a 1976 6hp Johnson. Compression in both cylinders is 50 psi.
Oddly, the motor runs well (pushes a 14 foot alu hull ~15 mph) and idles well. It does take quite a few pulls to start, 5 - 10. Warm restarts are pretty easy.
I am pretty confident the gauge is accurate - I cross checked it with a bike pump equipped with a tire gauge -- 50 equalled 50.
Soaked a couple days with Marvel -- no change.
Replaced head gasket - no change.
Cylinder walls look fine. Too smooth, but no evidence of damage.
So, next steps as far as I know:
Ignore the readings, accept the balky starting and run it.
OR
Replace the rings and lightly hone cylinders.
OR
Bore engine for OS pistons.
3 is pretty unlikely due to cost.
Are new rings often a good solution here? Or is that pointless? Is there some cause of compression this low I am overlooking?
Oddly, the motor runs well (pushes a 14 foot alu hull ~15 mph) and idles well. It does take quite a few pulls to start, 5 - 10. Warm restarts are pretty easy.
I am pretty confident the gauge is accurate - I cross checked it with a bike pump equipped with a tire gauge -- 50 equalled 50.
Soaked a couple days with Marvel -- no change.
Replaced head gasket - no change.
Cylinder walls look fine. Too smooth, but no evidence of damage.
So, next steps as far as I know:
Ignore the readings, accept the balky starting and run it.
OR
Replace the rings and lightly hone cylinders.
OR
Bore engine for OS pistons.
3 is pretty unlikely due to cost.
Are new rings often a good solution here? Or is that pointless? Is there some cause of compression this low I am overlooking?