Rebuilding a Stihl 025 - advice welcome

N2DFire · Jan 1, 2020

So my old faithful 025 finally laid down on me. The repair guy that looked at it says the cylinder (and piston) are scored. I lucked into a major deal on a new but older Husky e445 so I'm in no hurry to fix the Stihl so I figured I'd take a crack at it myself.

What other parts besides the cylinder, piston, and rings should I look at replacing? Also suggestions for kits to buy or stay away from and repair manuals / videos to check out.

Not exactly a novice at turning a wrench but small engine stuff is not my forte so I'm trying to get educated before the parts start coming off.

Thanks in advance for any information you care to share.

ericm979 · Jan 1, 2020

While its apart I'd also replace the wrist pin bearing, crank bearings and crank seals. Being an 025 (which they stopped making in the early 2000s, though the MS250 is very similar) it's probably seen a fair bit of use and those parts don't last forever. And check the wear items outside the engine like the clutch, drum and sprocket though you can replace them any time.

I have a Stihl 025 service manual I can send you. Stihl does a good job on their manuals.

N2DFire · Jan 3, 2020

ericm979 said:
While its apart I'd also replace the wrist pin bearing, crank bearings and crank seals. Being an 025 (which they stopped making in the early 2000s, though the MS250 is very similar) it's probably seen a fair bit of use and those parts don't last forever. And check the wear items outside the engine like the clutch, drum and sprocket though you can replace them any time.

I have a Stihl 025 service manual I can send you. Stihl does a good job on their manuals.

Thanks for the advice. I looked at one "kit" on Amazon but it had one review and it was bad so I'll probably end up piece milling the parts I need.

I would love a copy of the manual if you don't mind. That saw was second hand to me so I didn't get one to begin with. If it's electronic you can send it to n2dfire (at) hotmail (dot) com

Thanks!!

Liquidsilver · Jan 3, 2020

I have an 025 that's older than my adult kids. It just won't die... and Lord knows I don't give it an easy life. I've had to have the carb worked on and the recoil rope changed, but it just keeps on truckin.' I dropped a dead 6-foot diameter oak with it yesterday.

Industrial Toys · Jan 3, 2020

There are great sources for very cheap aftermarket chinese parts for various Stihl saws. I squashed my 036 last year and will get some.

N2DFire · Jan 3, 2020

Industrial Toys said:
There are great sources for very cheap aftermarket chinese parts for various Stihl saws. I squashed my 036 last year and will get some.

Yup - just ran across this one a little while ago, think that's going to be the ticket.
Stihl 25, MS25, 23, MS23 cylinder + overhaul kit

I'll tear the saw down first and make sure I don't find anything else that needs replacing before I order.

ruffdog · Jan 3, 2020

Be sure to do a pressure/vacuum test on the engine as the plastic clam-shell type crankcases are known to leak. I have repaired nearly new saws because they had an air leak. Use the correct sealant between the 2 halves too.

N2DFire · Jan 8, 2020

Thanks everyone for the advice, tips, and especially to Eric for the manuals. Those are going to help a lot.

Ended up ordering this parts kit. Figured for a back-up saw, no more often nor harder than I use a saw anyway, that this wouldn't be too bad.

Amazon.com: Hipa 42.5mm Cylinder Assembly with Spark Plug Replacement Crankcase Connector for STIHL 23 25 MS23 MS25 Chainsaw: Automotive

ruffdog said:
Be sure to do a pressure/vacuum test on the engine as the plastic clam-shell type crankcases are known to leak. I have repaired nearly new saws because they had an air leak. Use the correct sealant between the 2 halves too.

That's my next item up - pressure / vacuum tester - probably from HF unless I get really hooked on fixing small engines. LOL

Now the real challenge - finding the time to do the work. May be a few weeks but I'll post back on the results.

yomax4 · Jan 8, 2020

Good for you tearing into the saw. I've done 5 or 6 more just for fun but even though a 20 yr old saw runs good, It's amazing the difference you see with a new Jug, Piston and Rings. Some after market parts are ok and even if something goes wrong you can inexpensively go back to the drawing board or just drop in a complete low cost after market engine. Good Luck !