Quick piston question (Doh!)

[Aero Fifty]

So I took the top end off one of my aeros to investigate a strange rattling noise, thinking it was a bad bearing. Well the rod bearing looked fine but the top of the piston was caked in carbon so I cleaned it up real good with a wire brush.

While putting it back together I broke the top ring. Now for some reason I thought eh one ring is all it needs and put it back together. Well the noise was gone but it was down on power and wouldn't restart when I shut it off. I tested the compression...zilch

So i figure the excessive carbon must of been making the noise? Now I need to order a new ring set and cylinder gaskets.

My question is should I get a new piston or just reuse the old one? I noticed the ring grooves have lots of carbon build up but the piston/bore is smooth.

[Kenny_McCormic]

If its all smooth you are likely good to go. Check bearings for play.

[Wheelman-111]

Greetings:

Suggest you remove both rings and use a plastic or wooden instrument to scrape away all the carbon you can. Then use carb cleaner and a plastic brush to clean and check that piston carefully. Install a pair of new rings and see if you have compression. Don't use metal or risk ruining any chance of saving that piston.

[Wheelman-111]

Greetings:

Also depending on miles logged, you may wish to assess why you've got so much carbon buildup and correct.

[Lunytune]

Also depending on miles logged, you may wish to assess why you've got so much carbon buildup and correct.

I noticed the ring grooves have lots of carbon build up but the piston/bore is smooth.

You expect carbon under the rings on a 4 stroker because the oil rings scrape the walls clean and the compression rings are "unprotected" from the chamber.

I've got lots more experience with 4 strokers than 2 strokers, but so far, I haven't noticed carbon buildup under the rings of the 2 strokers I've rebuilt. Without oil rings, the oil in the system keeps the rings wet. So there's a problem with that much carbon in both places, the rings and piston.

Also, always replace both rings, not just one. And hone the cylinder to break the glaze. As far as replacing the piston, is there much play? You might want to consider a new jug and piston.

[eliteguy50]

Also depending on miles logged, you may wish to assess why you've got so much carbon buildup and correct.

I haven't noticed carbon buildup under the rings of the 2 strokers I've rebuilt. Without oil rings, the oil in the system keeps the rings wet. So there's a problem with that much carbon in both places, the rings and piston.

yes, carbon can be an indicator of bad or it could be 4000miles on a single ringset with cheap oil. I would clean it up and put the new rings on.

[Aero Fifty]

Thanks for the feedback I have the piston soaking in some solvent and hopefully I can get it spotless.
This particular aero lived a hard life as a pitbike and I'm pretty sure they thew in any 2-stroke oil they could get their hands on.
Now I just need to wait for my parts to get in so I can put it back together.

Anyone here try the scotchbrite pad method of honing the cylinder before? I figured since my bore is smooth I'd give it a try.