Saw building 101?

[LAWN BOY]

I'm getting a Stihl ms250 from my uncle for free, needs a new piston and maybe cylinder. I was leaning towards using aftermarket parts... Any recommendations on pistons and cylinders on a budget? I'm tossing around the idea of doing an all out build and learning some more stuff while I have it apart. It'll be my first rebuild. What's involved in porting? What tools would I need to do it myself? What about dying the plastics? I'd like to dye them black, what materials would I need for that? This will probably be a project for this summer, but we shall see.

 

[GMB74]

Dying the plastics is simple. Clean them up well, get some Rit dye and a big pot of water, follow the directions on the package.
Aftermarket parts are always a gamble. I have used the cheap no-name pistons and cylinders off ebay and they have worked. But maybe I have just been lucky. Using name brand parts like Hyway may increase your odds, or maybe not. Check the return policy on whatever you buy. If you are going to port the cylinder, you can get by with a lesser quality item because you are going to grind out the defects anyway.
Someone should be along shortly with more specific information regarding porting.

Get the shop repair manual to have handy in case you run into a snag when rebuilding.

 

[Woodwackr]

I wouldn’t spend much on it. That is a $200 saw when completely fixed up.

 

[GMB74]

It's not worth a lot of money, that is true. On the other hand he doesn't have to invest a lot of money. Aftermarket parts are cheap and generally of decent quality for this model saw. If it doesn't work out or blows up, he hasn't lost a lot. Just the cost of tuition for his learning experience.
Here's a thread with some good cheap and easy upgrades, once you get the engine repaired:

Thread 'Bernie’s MS250 Upgrade'

Oct 21, 2023

My good friend Bernie has a nice MS 250 that he’d like me to improve. Usage is for dead tree cleanup on his property and firewood cutting. Runs great, he takes care of his stuff.


After reading a bit more about this model, looks like a muffler mod is in order, but not much else. I hesitate to open it up and adjust intake and exhaust port widths.

Any suggestions on the muffler mod recommended for one of these?

• Paul Fithian
• Replies: 73
• Forum: Chainsaws

 

[hacskaroly]

I'm tossing around the idea of doing an all out build and learning some more stuff while I have it apart. It'll be my first rebuild. What's involved in porting? What tools would I need to do it myself?

Here is a video of a guy porting a clamshell Poulan (similar to the MS250), should give you a good idea of what you might need and how to tackle a porting project.