Worth trying to fix?

[Andrewnyc]

Hello,
i have an echo cs-370. I let it sit about ten years, pulled the chord and it started right up. Here is the problem, my neighbor lent me his gas - mixed 50:1 he said- was not.i didn’t know what was going on, over heated it, it started to seize, poured oil in spark hole and it immediately I seized.
Only have have 110 psi compression now, no leak. echo says I need 145 psi, so no fire in cylinder if I add gas to rest. Looked in spark hole and exhaust port cylinder has some minor scoring marks, piston top good, piston minor scoring.
Do you think it’s worth changing the rings to try to increase the compression?
thanks,
Andrew

 

[Bob Hedgecutter]

You wont be the first this has happened to, wont be the last.
Either with fuel mixed by others, or a fuel mixing mistake ourselves.

Photos will tell a truer story of just how good or bad things are, but you are going to need to pull the cylinder and inspect the interior of the bore for transfer of melted piston material to the cylinder walls.
Could be things were stopped early enough that the ring is stuck in the ring groove and it may be possible to free it up, but the odds are pretty good you will snap the ring trying to remove it.
The good news is, piston kits are available and it is not that hard of a job to replace one- but if there is transfer of melted piston material to the cylinder walls, the cylinder scored or port edges damaged, that will need repaired or replaced- as a new piston in a damaged bore will not last long.
Is it worth fixing? That is for you to decide, price of parts and if you are able to do the work yourself- versus the cost of a second hand or new saw of similar size. If you have to pay a dealer to fix, then probably not worth it.

 

[Andrewnyc]

Thanks for the reply. I will take it apart and post some pics to get a better assessment from you. I looked up the prices and may give it a shot. I do my own work so it shouldn’t be to bad price wise.

 

[Andrewnyc]

Ok so here is the cylinder, most of these marks cam right off with 400 paper by hand, there were two spots of deposit in bore, sanded out. The ring has a small score in it. Should I see if a new ring helps, or call it a day?

 

[Bob Hedgecutter]

That shows us the piston and not the interior of the cylinder.
Nice series of photos and the circled areas are a nice touch.
The interior of the cylinder need to be shiny and clean with none of that black smearing left (like you can see on the face of the piston) no grooves or scoring you can catch a small pick on or your finger nail on. No plating chips at the edges of any of the ports.
In my opinion- that piston is trash and the saw needs a new piston and ring kit.
Having said that- I have "recovered" similar looking pistons for saws where no replacement was available and found a new ring (or rings) from somewhere. However, as replacement parts can be found for this saw, that is the direction I would be headed.
If you have a saw pulled down this far and something internal is damaged, replacing the damaged with new at this stage renews faith that all is well in there and if treated well, it will not need attention again for a good long while.
In my opinion, that piston shows all the signs of straight gassing and an early save- so you did well to shut it down when you did and hopefully saved the need to also find a new cylinder.

 

[Andrewnyc]

Thanks for your opinion. Tomorrow I will post pics of bore, and cleaned cylinder, and I’ll see what up you think.

 

[Andrewnyc]

Ok here are some pics of after cleaning up cylinder, and the bore. There is a lot of reflection in there , but appreciate and input. I’m thinking get the ring, put together and see if I hit the 145psi necessary. I had 110 after running with very low oil and overheating a little.

 

[Bob Hedgecutter]

Yep- cylinder looks pretty shagged as well- still WAY too much transfer in there that might clean out, but the scoring looks too deep and some of the plating is missing in spots.

 

[Andrewnyc]

Ok thanks for taking a look. I guess it trash.

 

[Bob Hedgecutter]

Ok thanks for taking a look. I guess it trash.

Or keep for parts- you may someday find a same model that has case/handle broken, smashed exterior but a good piston and cylinder that can be swapped over to your old saw.
Or sell parts off what is left of yours.