Author Topic: Rebuilding Stihl series 021,023, 025  (Read 231 times)

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Offline deereguy

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Rebuilding Stihl series 021,023, 025
« on: October 30, 2014, 03:03:31 am »
A number of 025's have came my way, recently.  I thought, I would share my experience with rebuild these saws.  I believe the following information to be a bit elementary for this group, but maybe of some value to someone planning on rebuilding one of these saws. 

With my trusty Dewalt 20V, these saw comes completely apart in 15-20 min.  The following are my observations.  I'm not a tech.  Just a hobbyist.  With a little effort you can make a nice homeowner excellent performing saw.

1)  Seals and Sealant:  Suggest the use of new seals with every build.  Imports seals seem to be ok and reasonable .50 ea.  Leaky seals are common fault with this series.  It's doesn't seem to be necessary to put sealant around where the seal fits.

I've been using Dirko which works, ok.  My tube is several years old so planning to try another brand.  The right amount of sealant on the pan/cylinder base is critical.   Right amount:  Enough to slightly overfill the channel on the pan base plus a thin coating.  I haven't figured out what liquid cleaner is the best for cleaning the mating surfaces of the pan and cylinder???  I'm hoping someone can better describe/ recommend process to apply sealant.

2)  Tork the pan to the factory spec.  The pan is flexible and prone to leak/ flex, if over tightened.

3)  Suggest changing the carb out to China fully adjustable.   They cost $12 and improve the performance.  Not to mention, the convenience of being able to fine tune the carb.

4)   Change the clutch from the OEM spur to a rim setup $17.   A nice cutting performance improvement.   The 025 seems to do well with the 3/8 pico

5)  I've had more than one issue with pressure leaks with this series.  So, don't forget to pressure test after assembly.   I find it convenient to pressure test the pan/cylinder assembly out of the case.  Use the metal grommets in the case with the pan screws.  Grommets push out of the case easily.

6)  I generally open the muffler exterior baffles up and remove the screen.   Of course, this would be a personal decision.

Anyone suggestions clarifications???  I might not be able to respond promptly, as I'm on duty to watch my youngest great grand daughter tomorrow.  rick
   

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Offline 660magnum

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Re: Rebuilding Stihl series 021,023, 025
« Reply #1 on: October 30, 2014, 06:39:59 am »
Try the Stihl PS chain in the 3/8 low profile applications.

The genuine twin needle Stihl WT-215 is like $22.50 at the Stihl dealer.

On the muffler I remove the whole indention behind the screen and open the outlet fins way out with the bar nut - spark plug wrench. Then I open all the holes up in the cage with a drill at the muffler inlet that I reach.

I have a extra set of pan grommets from a old case.

I take a sheet of 320 wet or dry sand paper on a sheet of glass and level off the mating surfaces of the cylinder and pan before assembly.

I have Dirko also

A alternative would be the off-white Three Bond 1194

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Offline 660magnum

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Re: Rebuilding Stihl series 021,023, 025
« Reply #2 on: November 01, 2014, 09:39:13 pm »
One thing that comes to mind with the Stihl Clamshell saws  (MS 210-250 & 290, 310, & 390) There are smaller saws too. The problem is the bottom cover or pan coming loose after re-assembly of the engine unit into the plastic outer case.

The solution is partially covered in the first post of this thread but to carry through with the solution, In addition to new seals, it talked about cleaning and leveling the mating surfaces and using a sealer like Dirko or Three Bond sealer on them (not PVC). It has also been mentioned to bolt the cover down outside the saw. This is considered important.

Then let the engine unit set on the table until the next day all bolted up before you touch it again. This is an attempt to let the gasket sealer set up.

Then carefully remove the bolts and place the engine unit in the plastic housing and re-install and torque the bolts from underneath the housing. Try not to bump the engine unit or do anything that would loosen the pan while placing the engine in the plastic case or installing the retaining bolts.
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
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Offline deereguy

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Re: Rebuilding Stihl series 021,023, 025
« Reply #3 on: November 03, 2014, 06:22:58 pm »
Good idea about letting the assembly sit overnight.  I haven't done in the past.  I generally go right to pressure testing. 

I don't recall having issues with sealing on the 029 series.  The 025 series has been a challenge.  I either get too much sealant or too little.  Also, I should have mentioned, make sure to get sealant at the corner of the each of the bearings (small depression).    rick

Offline 660magnum

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Re: Rebuilding Stihl series 021,023, 025
« Reply #4 on: November 03, 2014, 06:25:48 pm »
+1
We should share what we know... someone may learn...
That knowledge can live after us... and that "Pays It Forward".
Be all that you can be . . .

 

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