Worth it fixing this saw?

[seagull369]

I bought a Makita saw on the cheap the other day (Dsc400 I think, for $50). It didn't lite up despite spark & ether and had absolutely no compression, so I ripped 'er open and found the piston scored and the head very lightly scratched on one side.

My bigest concern, i guess, is the head. I figure replacing it would too cost prohibitive for me so was wonderin' if a shop might be able to machine it or even just smooth out affected area (or maybe I could do the latter with an emery cloth?). Then I could toss in a new piston (or larger one if it's bored over) + new ring and be on my way.

ANy thoughts on that idea?

If I decide to fix it, is there a trick to getting that wrist pin out? I thought it was pressed in, but when I press a small screwdriver on it and twist, I can see it twirlin around in there (wouldnt think a pressed pin would behave like that). I thought about tryin this setup with it:

http://www.rudigreyling.com/pictures/rotax/rotax_13.jpg

but not sure if it'll work.

 

[Bowtie]

There is a wrist pin circlip on both sides holding the piston in. You will need to remove that. Also, Its not feasable to bore a chainsaw cylinder because it will have to be coated with chrome or nikasil. Usually you can clean up the cylinder with muriatic or hydrochloric acid. Do a search, lots of info here on that.

 

[zr900]

There should be cir-clips holding the wrist pin in, use a small pic to remove and them, and then the wrist pin should slide out.

Second DONT use ether to try to get a 2-stroke to fire!

 

[seagull369]

Wow, thanks for the speedy replies. I didn't realize the bore face was anything more than just milled aluminum (alloy) up in there. I wonder if using muriatic would remove any coating that might be on it now. I'll check for those circlips. I looked pretty close up but didnt notice any and but I coulda missed it.

Thanks for the ether warning. I knew about the probs with it (thanks to the site here), but I got weak!

 

[nmurph]

muratic acid will not hurt the nickasil coating. it will remove the AL transfer, just keep it out of the ports.

 

[Teddy.Scout]

I have been fortunate with pretty clean cylinders.
I saw my neighbor freaking run a Small engine hone through a jug(for way to long) on a craftsman saw. How long before that heat would warp the cylinder?, from the coating being removed.

 

[pioneerguy600]

I have been fortunate with pretty clean cylinders.
I saw my neighbor freaking run a Small engine hone through a jug(for way to long) on a craftsman saw. How long before that heat would warp the cylinder?, from the coating being removed.

No worries about warping the cylinder but it does not take very long to destroy the lining. If the cylinder is of the older unlined aluminum style then it does not take long to either oval the cylinder or oversize it to where it is useless. The older cast iron lined cylinders could be bored and honed and a new oversize piston installed but todays cylinders don`t need honing unless trying to remove aluminum transfer, even then use the hone sparingly.Ball hones catch in the intake,exhaust and transfer ports so they have to be used very little and also very carefully. Cylinder hones like the brake hones can also catch the ports and cause worse damage to the cylinder and the hone.
Pioneerguy600

 

[Teddy.Scout]

Thanks!
good info, going to need it here shortly!!!!
Thanks