Hi Randy:
Thanks for the prompt reply.
The "scratches: run the entire length of the cylinder wall and are parallel to the piston travel from the bottom to the top. This is good? It means that the ring is an equal area cylinder abuser. If the scratches were only present above the bottom of he stroke, then I would think that the cylinder/ring fit was bad. In this scenario, It makes me think that the marks are not scratches but marks caused by burnishing the high spots off the cylinder wall. Or could they be caused by irregularities on the face of the ring? No matter what the cause, no compression!!!
Any thoughts/suggestions?
Be well,
Frank McCune
Hi Frank
The surface needs a "cross hatch" in the cylinder liner to help facilitate the break in of the ring, scratches running up and down the liner will NOT do anything to help the ring seat,, and will actually hurt it, these were made by the up and down motion of the piston, You can take a brake cylinder hone and rough up the surface before installing a new ring, the cylinder honing CANNOT go just in a motion around the sleeve, it has to swirl up and down, so you need to move the sleeve back and forth while the hone is running, then remove the hone, switch the the opposite end of the sleeve , and do the same process, you just need a light honing, do not try to grind on the sleeve, just enough to see the light swirl marks, after clean it all well, and fit a ring with about .001 gap for non chromed, or .0025 for a chromed liner. I would spin the engine over many times before cranking it, just put some light oil in the cylinder, and spin the prop with your hand, many times like several dozen, then spin the other way, this will start the process of wearing in and the ring seating, without it getting hot and taking a chance of the end gaps touching, if the crosshatch is doing its job it will open up the gap as it seats, Some people use a drill to spin the engine over, again this will help seat the ring and make sure its not getting too hot. Afterwards when you run it on the bench, run it sloppy rich, and do not lean it until you have 2 or 3 runs on it, Then you can pinch the fuel tube, and let it burst into a two stroke for a few seconds, do this at least a dozen or so times each run, You will be able to tell quickly if teh ring seats in well.
Hint the steel sleeve will cut easy, the chrome one will take a much longer time.
another Hint I told you a while ago, some sleeves will NOT ever take a ring and seat properly, that was the reason I suggested a New liner for one of you engines.
If you try to breakin a ring with the type sleeve you are asking about, it will NOT seal, and you will just quickly ruin the ring, Then you will have to get another NEW ring to install.
Randy
Also if this is an OS liner with nickle, then it is toast ! you cannot do anything with them except for honing and having the liner chromed