Stihl MS 261 rebuild questions

[angelo c]

Pry the caps/covers off the muffler screw holes in the center of rhe muffler. The bolts are t27

 

[huskihl]

You can usually clean up the cylinder if there’s no deep scoring. Oem piston is $35

 

[Spladle160]

I would be livid if my 17 month old barely used pro level auto tune chainsaw lean seized on properly mixed fuel. If Stihl didn't make it right ASAP I would start calling lawyers and reporters. Worrying about rebuilding it myself would be well down my list. Of course i would have no warranty because I wouldn't have run their oil and would have opened up the muffler and advanced the timing at a minimum.

 

[lehman live edge slab]

The oil wouldn’t have voided the warranty but the other stuff does. They only give the double warranty to get you to buy the Stihl ultra

 

[Spladle160]

Sounds like their warranty may not be worth more than the paper it's written on anyways.

 

[MustangMike]

My advice: The saw s/b covered by warranty, but if not:

If either of you have to rebuild your saws, I would try to clean the OEM cylinder (their are videos on how to do it by Randy/Mastermind) and use either a Stihl or Meteor piston. Meteor pistons (which come with Caber Rings) are top notch, not so much their cylinders.

I would not use Stihl Oil in the future, it sucks! I like AMSOIL Saber at 40:1, and I have a ported 261 C V II and it runs just great on it. I have seen many saw failures with the use of Stihl Oil.

 

[deraeler]

Did a little digging - it appears if they removed teh little rotary clips that hide the muffler screws the dealer must have re-installed them, most people seem to replace those once removed. Still have no idea how they got those clips off, special tool?

Still hoping for a service manual and some video resources - anyone? Thanks!

 

[deraeler]

Thanks to Ray for the manual resources...! One goal accomplished, back soon.

 

[deraeler]

Sorry for the newb questions - does 'ported' mean rebuilt with an aftermarket cylinder?
What tool is used to perform a vacuum test / compression test? Any how-to's available?

 

[RI Chevy]

Think of ported as a high performance hot rod. Built up engine by using tools to enlarge the openings of the OEM Cylinder. More in, more out.
I'd stick with OEM. After market is a cheap alternative, BUT, lots left to be desired.

 

[RI Chevy]

Mityvac

 

[MustangMike]

Porting means that the ports in the cylinder (OEM or AM) have been modified to optimize performance.

To Vac/Pressure test a saw, you must seal the exhaust port, intake port and hook something to the impulse line (like this).

I believe this is the devise that is most commonly used by folks on this site: (don't go over 10 psi).

https://www.amazon.com/Mityvac-MITMV8500-Silverline-Automotive-Vacuum/dp/B0002SQYUA/ref=sr_1_3?dchild=1&keywords=vacuum+pressure+tester&qid=1593188147&sr=8-3

 

[deraeler]

Answering my own questions...I see the tools listed in the SM. I see vac/testers on ebay ranging from $70 - $360.
Trying to determine all tools needed for the cylinder rebuild....will take some time.

 

[RI Chevy]

Have you pulled the muffler to get a peek at the insides? The cylinder and piston?

 

[deraeler]

Porting means that the ports in the cylinder (OEM or AM) have been modified to optimize performance.

To Vac/Pressure test a saw, you must seal the exhaust port, intake port and hook something to the impulse line (like this).

I believe this is the devise that is most commonly used by folks on this site: (don't go over 10 psi).

https://www.amazon.com/Mityvac-MITMV8500-Silverline-Automotive-Vacuum/dp/B0002SQYUA/ref=sr_1_3?dchild=1&keywords=vacuum+pressure+tester&qid=1593188147&sr=8-3

Nice Mike, thanks!

So I'm not looking to port/optimize, just replace the scored cylinder, and try to address whatever caused the fail in the first place.
I can't tell by that product description whether this pressure/vac test k it includes these tools listed in the CM:
- Nipple 0000 855 9200 Testing carburetor for leaks
- Hose for leakage test 1110 141 8600 Testing carburetor for leaks
- Plug for leakage test 1122 025 2200 Leakage testing decompression valve
2 Sealing plate 0000 855 8106 Testing crankcase for leaks

There are of course numerous other tools listed in the CM, trying to determine which would be needed....bit of a long study.
Baby steps...

 

[RI Chevy]

You'll need to pull the carb off and muffler off and block them both off. Stihl sells plates I think.
They can also he made if your handy by tracing the ports.

 

[heavy_oil_saw]

I built an MS261 MT from “parts”, even managed to source a 2nd hand slant fin cylinder, but built it first with a horizontal fin cylinder, both worked.
Here’s a suggestion for the press & vac test kit, from the photos, 3mm rubber sheet cut to size and same with some tin sheet. For the adaptor I cut the lip that secures the ceramic part of the spark plug off and removed the ceramic part, and stuck a suitable pipe in there (it’s Plexus adhesive). The Mityvac press tester has an adaptor that worked with the pipe.
Never built a saw, but have a mechanical background, so helped. This forum was very helpful sourcing information on M-Tronic, and I bought a maint booklet, now I have a running saw.


Sent from my iPhone using Tapatalk

 

[RI Chevy]

Very nice.

 

[MustangMike]

Unless you have gouges in your cylinder, clean it up. This is one of Randy's videos, there are a few of them.

Follow what he says, it works (may take a while). Be carful near the ports.

https://video.search.yahoo.com/search/video?fr=yfp-t&p=removing+transfer+from+chainsaw+cylinder#id=5&vid=58985b571b7cd652ca2af8e1c12890bf&action=click

 

[Spladle160]

@heavy_oil_saw that's not the prettiest set up I've ever seen but it looks 100% effective and you're pics do a great job getting the idea across. The only thing I would add is make sure to rotate and push and pull on the crank some while it's under vacuum.