Mark on cylinder wall By masterburt (Read 802 times)

[masterburt]

is this a bad thing engine has only been started a few times,o miles driven lost compression 100 psi now. still feels flush ? 

[cyborg]

wrist pin clip get out of it's groove? or a ring break?,,,probably can hone it out and rering i would think

[masterburt]

thats the problem wrist pin fine so is the piston rings the compression is at around 100psi and when you plug your thumb again the sparkplug hole and crank it seems not to suck my thumb with force,unlike other engines

[Guitarman]

Looks like hell in the pic. Hey, this is America! Just sue someone over it. You'll get money and a free one for life if you win your case....

[kevinharrell]

Since it is just make sure that the circle clips on the wrist pins are not rubbing, the rings are good and run the engine. When I say run the engine I mean that you should ride the bike. The compression should get better when the parts start to wear together, you know, the regular break in process.

[jct842]

On a 2 stroke the rings have to be set so that the end of them does not line up with the ports as the groove in picture indicates…

[jct842]

I was in a hurry when I posted on this before. I should have mentioned that most of the 2 strokes I have had apart for rings have a piston that is pinned. In the ring groove is a tiny pin sticking up. The rings have a matching notch at the ends. This is so that the rings can only be installed with the ends at the proper place in the grooved piston. If a ring end is left in a port it will more than likely at least chip off the end of the ring and score the cyl wall. With the score in your cyl wall where it is tells me that that almost had to be incorrectly installed rings.

I learned about 2 stroke rings the hard way when I was 16. I had a JAMES motorcycle that I bought real used. I broke rings regularly. The man at the briggs and stratton repair shop showed me what I was doing wrong, but it was a little late in the game to save the cyl. It had worn so badly that at the bottom of the stroke you could take your finger and push the piston side to side yet at the top of the stroke it was tight! Learned a lot with that old piece of junk, my dad gave it to the junk man when I left for the navy. In a worn cyl you test fit the rings in the tightest place in cyl and see that the end gap is correct there also. If the end gap is too tight or not at all you stand to trash the cyl too.

[royldoc]

Any marks on the piston? Two stroke pistons have a locator pin that keeps the rings from being installed wrong and also keeps them from spinning on the piston so the ends of the rings don't get caught in the ports. Is it possible the piston was installed wrong? They usually have an indicator. if not it may be the ring pin that determines which way to install the piston. It may have been a small piece of foreign material that went into the port. Hone it out and install new rings depending on how deep the groove is. If it is to deep and you hone the cylinder to far the rings may not seat and a loose cylinder may create a piston slap condition.

Roy

[masterburt]

yes the piston has locators on them,I'm more going with the me installing it in a rush and them getting caught up.Problem is that where you can see the mark is exactly where the locator pins on the piston sits,am i right in saying the aarow on the piston should be facing the exhaust port this is the horizontal engine.