nm

[MR_T]

Well, should I be worried here with the color? I did a trade for a saw without asking for piston pictures.. Was told they put a used piston in with new caber rings, so I assumed everything would look fine..

 

[cuinrearview]

I don't understand. Is it the color you're worried about?

 

[MR_T]

I don't understand. Is it the color you're worried about?

yes, first time seeing this on a piston.

 

[farminkarman]

yes, first time seeing this on a piston.

I wouldn't be worried about the color. I thought maybe you were worried about the scratch lines on the piston.

 

[MR_T]

I wouldn't be worried about the color. I thought maybe you were worried about the scratch lines on the piston.

I see that now. early scoring marks?

 

[farminkarman]

I see that now. early scoring marks?

Have you run it yet? If not, then it might be worth pulling the jug and making sure there isn't transfer on the cylinder bore.

 

[MR_T]

Have you run it yet? If not, then it might be worth pulling the jug and making sure there isn't transfer on the cylinder bore.

Yea, maybe 5 minutes

 

[hacskaroly]

Yea, maybe 5 minutes

If you do pop the top and everything looks ok, you might use some SeaFoam and a green scotch bright pad to work the discoloration/carbon off. It will easily take that discoloration off without much pressure.

 

[MR_T]

If you do pop the top and everything looks ok, you might use some SeaFoam and a green scotch bright pad to work the discoloration/carbon off. It will easily take that discoloration off without much pressure.

Is the color from running hot or rich?

 

[jacktheripper]

Is the color from running hot or rich?

That looks more like crappy oil. Carbon left from unburnt oil.

 

[hacskaroly]

Is the color from running hot or rich?

That I don't know, I generally work on free or project saws and they usually come with issues. Looking at the carbon in the exhaust tube, its possible that the saw has sat idling at times and so it has not been able to fully run clean (hence the unburnt materials collecting). Looking at pictures of those on the forum running heavier oil mixtures (40:1, 32:1) their pistons look clean, so I would guess maybe at times the saw is hot then sits and idles and the unburnt stuff starts sticking to the hot surfaces. This is just a guess on my part.

 

[huskihl]

It’s possible that it got hot but that usually doesn’t happen if the saw sounds right and is 4 stroking out of the cut (unless it has a limited coil obviously). Usually when I see that it’s from the owner running *s-wordty oil that doesn’t burn clean. Could also have been run with a plugged up exhaust screen causing heat to stay in the muffler

 

[MR_T]

That I don't know, I generally work on free or project saws and they usually come with issues. Looking at the carbon in the exhaust tube, its possible that the saw has sat idling at times and so it has not been able to fully run clean (hence the unburnt materials collecting). Looking at pictures of those on the forum running heavier oil mixtures (40:1, 32:1) their pistons look clean, so I would guess maybe at times the saw is hot then sits and idles and the unburnt stuff starts sticking to the hot surfaces. This is just a guess on my part.

Yes, there is more buildup than I'm used to seeing. I'm not a big-time builder. I know how to take things apart and put them back together, but it's the diagnosing that I'm learning when it comes to stuff like this.

 

[jacob j.]

I see that now. early scoring marks?

Naw - those look like pretty average wear marks to me. Most two-cycle pistons will pick up wear lines or marks. Apart from the burnt oil residue Kevin mentioned, that piston looks pretty good. A lot of the original machine marks are visible.

 

[dangerousatom]

Id say crappy oil too, or running a very rich mix a few tanks and oil built up in the bottom of the CC. Then the saw was run near upside down just before you go it and the oil burnt onto the piston. Id pull the jug and look at the chamber after you compression test it....if its low.

 

[dangerousatom]

What saw is it? an older saw with no side transfers will leave oil in the CC more then ones with them.
.
.

 

[cuinrearview]

Valvoline Restore and Protect at 29:1 for three tanks="problem" solved.

 

[cuinrearview]

I wouldn't be worried about the color. I thought maybe you were worried about the scratch lines on the piston.

Now look what you've done

Have you run it yet?

I raffed

 

[farminkarman]

Now look what you've done

I raffed

Well, it looked to me like old carbon buildup with new scratch lines. Seemed like maybe a case of a good used piston + saw that had previously burned down and wasn’t properly prepped. Either way it looks like I led to this getting blown out of proportion

 

[MR_T]

Well, it looked to me like old carbon buildup with new scratch lines. Seemed like maybe a case of a good used piston + saw that had previously burned down and wasn’t properly prepped. Either way it looks like I led to this getting blown out of proportion

no worries