Stihl 025 cylinder dilemma...

[Stihlofadeal64]

Hey guys, thought I'd throw this question out. I have a box full of parts I've had for ages of Stihl 025/MS250 stuff. I understand there are a few differences in the saws. I've probably built (in days past 25 or 30 already but its been a while.) I picked up a parts saw this weekend from a guy and have some leftover stuff to pull the saw together. Here's my dilemma. One of the differences between the MS250 and the 025 is .5mm. I don't have a dial bore gauge so I can't measure inside.
Since the cylinder is slightly tapered it's hard to tell whether it is a MS250 or an 025.

I have both pistons (42 and 42.5mm). They both fit in the cylinder, one very snugg, and the other with some clearance (without the rings they both dropped clean).

The markings on my cylinder read as follows:
1123-025
>AL<
BR

(not sure if Stihl indicated in some code which one this is or not, maybe someone can chime in. I know on the 029's and the 029supers and the MS290's they have specified 45 and 46mm).

Is there a way I can check the cylinder to see what it is by the markings, or another way I can measure to identify without a dial bore gauge? I am not sure how much clearance should be between the piston and the wall without the rings, or can I check/measure or identify it some other way. It's late and all this may be fuzzy, but I'm just trying to verify. Thanks in advance for your replies. Tommy

 

[H 2 H]

Here is a 2011 MS 250 cylinder

Numbers

Here is the piston I used in the last rebuild

Ring gap I cant remember off the top of my head but I think it was .011 - I should have wrote that down

 

[Stihlofadeal64]

Thanks for your reply. My concern was that Stihl had changed the size and included that in some code in the markings. Perhaps some of the other clam-shell experts can chime in as to their experience with these cylinders.

I once built a MS250 and put the 025 piston and rings in. It would never idle properly or run properly. Couldn't figure it out so I took it to a local dealer. They had three of their guys go through the saw (3 times) and no one could figure out why it would not run. Then it dawned on me that the piston is .5 too small. Broke it down and swapped out the piston -- cha-ching! All went fine! :msp_wink:

 

[Stihlofadeal64]

What I found as a solution was: I put the ring in the cylinder (both of them) and checked the ring gap. This allowed me to determine which cylinder was the right one for my piston. I also found that the larger cylinder was still marked "025". Cranked the saw after the build and it runs great!

 

[H 2 H]

What I found as a solution was: I put the ring in the cylinder (both of them) and checked the ring gap. This allowed me to determine which cylinder was the right one for my piston. I also found that the larger cylinder was still marked "025". Cranked the saw after the build and it runs great!

Thats what i wanted to hear

 

[Blade]

I'm opening this old thread as the MS250 cylinder and Meteor (42.5mm) piston photo's are identical to the parts I'm using on a customers chainsaw....or at least attempting too.

I'll say upfront that I don't generally do much more than general service work on these mid-range saws, as my core business is rebuilding large pro saws. Accordingly I don't profess to be an expert on the MS250.

Long story short a customer brought in an MS250 that upon inspection had a damaged needle bearing were the conrod connects to the crankshaft. The cylinder was fine, so I just grabbed a good used MS250 crankshaft from a box of parts I have in the workshop, put on a new Meteor piston, new oil seals, bearings, a bead of Dirko, and the job was done...or so I thought.

Before placing the assembled motor on the crankcase I hand turned the crank to ensure everything moved smooth, however I couldn't get a full rotation as the piston was hitting the top of the cylinder.

Pulled it apart and the crankshaft had Stihl part # 1123 / 68 LJ stamped on it. I know many of these small model saw had multiple variations, so I checked the Stihl IPL's for the 025, MS250 and MS250C to make sure I was using the correct part.

The IPL's showed 1123 / 0400, and 1123 / 0408 as the normal crankshafts used in all models, along with a 1123 / 0410 as a Brazil only model. There was no listing whosoever for the part 1123 / 68 LJ.

Call me a poor dumb simple Aussie, but am I missing something here with this crankshaft ???

Any assistance would be greatly appreciated.

 

[smallengineredemption]

Thanks for your reply. My concern was that Stihl had changed the size and included that in some code in the markings. Perhaps some of the other clam-shell experts can chime in as to their experience with these cylinders.

I once built a MS250 and put the 025 piston and rings in. It would never idle properly or run properly. Couldn't figure it out so I took it to a local dealer. They had three of their guys go through the saw (3 times) and no one could figure out why it would not run. Then it dawned on me that the piston is .5 too small. Broke it down and swapped out the piston -- cha-ching! All went fine! :msp_wink:

Anybody know the year they went to the 42.5??

 

[DND 9000]

The change was in the year 2000.

 

[smallengineredemption]

The change was in the year 2000.

How did you learn this?, seems much later than I would think

 

[DND 9000]

Reading the right Information, lol

 

[smallengineredemption]

Could you be more specific

 

[DND 9000]

The info is from an old Technical Information from 2000.