200 Johnson question

[logrady]

I have a 1994 Johnson 200 horse, model no.VJ200SLETF. Number two piston is chewed up on top and so is the combustion chamber. Head surface looks okay. The lower ports on top and bottom have a good size chunk missing from them. I'm asuming that's how the piston and head were damaged. Any idea what causes this? I've heard number two is weak in some way on this motor? Should I do a complete rebuild or can I get get away with using the other good five piston's and sleeve number two?

 

[Dhadley]

Re: 200 Johnson question

Yes you can sleeve the one cylinder and re-ring the rest if they measure in tolerance after the final hone. Regardless of how "good" they look. This final size is what we call the finished bore size. Its the final actual size of the cylinder taken at room temp.<br /><br />The wear tolerance (life) of that motor is .004". Lets say the other cylinders measure .002" over standard. That means 1/2 the life of that cylinder is gone (or left - depending on how you look at it). Lets further assume you hone it with an automatic hone and can hold the tolerance to .0005" (1/2 of a thousanth) and that it cleans up. Youll then have .0015" (1 & 1/2 thousanth) life left. <br /><br />If you get carried away with the hone and knock out .0015" you'll be down to .0005" wear (life) left. This is why measuring the block correctly is so important.