First saw rebuild couple questions.

[STLfirewood]

I have an Echo CS670 that I would like to make run again. The saw was ran a little lean. Not to bad but it did suffer a little damage. None of the damage will grab a finger nail. It was still running (but not good) when it was taken apart. Here are some pics. I am thinking that I can re ring it and hone the cylinder. What do you think. Also I am going to remove the base gasket. Do I need to adjust the intake and exhaust ports when I do this? I included a pic of the ports. What should a beginner do to them. I'm going to mod the muffler also and put a new carb kit in it. Please lead me in the right direction. I always did like this saw I hope to make it run really good again.

Scott

 

[PB]

Do you have a compression reading before tear down?

 

[STLfirewood]

The shop did one it was over 100 but not more then 125. I can't remember exactly. Here is a picture of the ports.

 

[PB]

Your piston doesn't look that bad, and I will be condemned but you could clean it up with some very fine grit sand paper or emery cloth. New rings are in order as well as a hone. Should get your compression back up.

I am not the person to ask about the gasket and port situation.

 

[pioneerguy600]

Your piston doesn't look that bad, and I will be condemned but you could clean it up with some very fine grit sand paper or emery cloth. New rings are in order as well as a hone. Should get your compression back up.

I am not the person to ask about the gasket and port situation.

I rebuild a lot of saws and that piston looks good enough to be put back in service for a while to run the saw as stock but if you want to hot rod it by leaving out the gasket,increase compression, raise the exhaust port lower the intake the thickness of the gasket removed and widen out the intake and exhaust ports as a starting point then you should think of using a new p and c kit. The existing piston could be cleaned up with fine emery cloth and a new set of rings then hone out the cylinder and it would run good enough to cut wood for several years. IMO. Pioneerguy600

 

[djohn]

You should check your squish with a piece of solder before just taking out the gasket. Too tight make it go boom. 0.020 is a safe distance between the squish band and the piston. Widening the ports but not changing the timing would give you some more power but can cause more wear on the piston which in your case is already not fresh. I would recommend doing one mod at a time though and see how it performs, tear it back down and make another change. You will learn more about hotrodding a 2 stroke that way and it gives you more tinker time.

Good luck and have fun with it.

 

[STLfirewood]

I'll clean the piston have the cylinder honed and re ring it. I'll leave all the ports stock and start off with a muffler mod. If I just get it to run right again I think it will be a success.

Thanks Scott

 

[CharlieG]

Clean the piston up, replace the ring(s), hone up the cylinder, and replace the base gasket with a fresh one. After the saw is up and running, and broken in, then start the mods like STLFirewood said (+1). Start off with a good platform, and I think you''ll be more successful in you hot rodding.

 

[blsnelling]

That piston doesn't look to me to have been run lean. No scoring at all. You have a few wear marks, but nothing more. I wouldn't go polishing on the piston skirt either. Maybe some 0000 steel wool. No sand paper. You want to keep those little circular lines. They help hold oil. I'd remove the deposits near the ring grooves, break one of the old rings and clean out the grooves, hone the cylinder, and put back together with new rings. Be careful with your honing as well. It shouldn't take much. Also, you cannot just pull a base gasket. Get the squish too tight and you'll have problems for sure.

 

[Zodiac45]

rebuild

I agree with Brad about the honing. As little as possible to clean it up as the cylinder bores are usually coated versus plated these days.

 

[huskydave]

I would replace the piston. Their is some wear on the skirt and the scratches go up to the ringgroove. you could get away with using it but pistons are pretty cheap your call.