Re: Johnson a65 scored pistons?

[need2fish]

Before spending your money on rings, mic the bores — if the runout from the bottom to the top is more than .020 (in my experience), rings may not help — the balloon in the ring wear zone may be where your compression is going. Given the shape of the piston skirts, I`d say you`ll see some significant wear. Bore should be 1 7/8".

Also, make sure the block is not leaking where it joins the crankcase, and top and bottom crank bearings are not leaking.

Lastly, pull the carb and evaluate the rotary valve for wear or damage.

I have both the A and K inline motors and they suffer when there is carbon build up in the area between the exhaust chamber and the leg. The right angle turns get loaded up with carbon and the motors lose top end and accelerate slowly (because exhaust is not getting scavenged out of the exhaust chamber).