MS 260 MS 261 Problems. Should I rebuild? What Am I Doing Wrong?

[Jrlh]

In '09 I bought a new MS 260, ran the saw for 3 years cylinder seized, so I went ahead and traded it for new MS 261, Love this saw, treated with kid gloves. I only cut about 3-4 cord per year, always use Sthil 2-cycle oil. Then this spring saw died, and would not re-start...Took to dealer, piston looks like it got hot, low compression, dealer says it happens with cutting in hot weather? Dealer wants 500.00-600.00 to rebuild? Tells me I am better off to just buy a new 271? Offer me 20.00 for my old saw, said it is good for nothing but parts?
Anyway, I took my saw home, bought a cheap new Husky to get me through the winter while I go over my options. Just can't believe my MS 261 that cost me over 600.00 new, is just a throw away saw, or one that costs as much to repair as to replace? I'm mechanical but have never attempted to rebuild a saw. Should I tackle it? what can go wrong? .....Hate to be too wordy, but looking for some solid advice, on what others would do in my situation. ...and oh yea, am I tearing my saws up? Why the bad luck?

 

[jltrent]

If the saw was not straight gases then the crank/rod bearings are probably good. Also the cylinder will probably clean up with acid and hand work. A new meteor piston and fix what caused the lean condition and it will be a nice runner again. You will be surprised how good it will be after a few tanks put through it. I just did a MS290 like this and it looked pretty bad when I started. I put new bearing /seals and the rod bearing was tight. After a couple tanks it has 152 lbs. compression and I can't tell any difference than others I have at 160 lbs. plus.

A $39 piston and on the pro style MS261 at the most 2 hours and it will be ready to go.



https://www.wolfcreeksawshop.com/pr...r-stihl-ms261-ms271-44-7mm-italy-caber-rings/

 

[Tinman204]

Couple things I"ll mention.

Make sure your saw 4 strokes at WOT out of the wood and cleans up in the wood. If your 261 is an m-tronic then it shouldn't be lean although I have very limited experience with m-tronic stihls.

Make sure your chains are sharp, a dull chain on a 50cc will kill it pretty fast.

My neighbor gave me an ms 260 last year that had like 10 tanks through it. Piston was scored pretty bad.

I had to cut the limiters off the carb to get it tuned rich on the high speed jet.

The chain was so dull it wouldnt slice air let alone wood.

With some sand paper and patience you can ckean up the aluminum transfer on the cylinder and as noted above install a quality piston and your saw shpuld be good to go.

 

[thomasinvancouver]

I would fix it. If you have a bench and some tools; worst case is you’re out maybe $200 in parts and special tools but with much more knowledge.

 

[Jrlh]

Thanks for the advice, and ideas on what happened, and what can be done. You have given me just enough courage to tackle this...Ordered the parts today....So we will see!

Hope I can pull this off...Two saws are always better than one and besides I didn't need another boat anchor!

 

[Jrlh]

Thanks for all the advice....!! I was able to pull this off! Saw will still go to the shop, to make sure the original problem that caused the lean burn is addressed, but she will start and run with the new piston! Just do not want to re-damage it before getting her checked out!

 

[John Lyngdal]

Are there any carb adjustments on the saw?
Just wondering if it was a M-Tronic saw.

 

[Jrlh]

Are there any carb adjustments on the saw?
Just wondering if it was a M-Tronic saw.

Yea, although the limiters are still in place....I started it and ran it for a bit...Wants to bog, but I can keep it running if I feather the throttle, it's not four stoking the second or two I WOT and I think still running too lean, because when I pulled the exhaust it looked like the new piston had more than the 3 or 4 minutes of run time I put on it. So I don't want to chance it.

 

[Tinman204]

Yea, although the limiters are still in place....I started it and ran it for a bit...Wants to bog, but I can keep it running if I feather the throttle, it's not four stoking the second or two I WOT and I think still running too lean, because when I pulled the exhaust it looked like the new piston had more than the 3 or 4 minutes of run time I put on it. So I don't want to chance it.

Before you take it to the shop you should check a few things. You're in a great position to learn saw repair and if you take it to a shop you will miss out.

Also if you don't learn how to adjust your carb you will probably burn down your saw again..

First things first, does the saw idle properly? If you tilt the saw up, down and left and right does the idle change?? Make sure your fuel line is in good shape and that your tank is full while doing this.

If your idle changes I'll bet money you need a set of crank seals.

If it idles fine in the above listed positions then remove those carb limiters off and richen up the H jet by turning it counter clock wise. They limit carbs these days for EPA rules which more often then not makes then run lean.

Keep turning out the H jet a little at a time until you hear the saw 4 stroke which sounds like a blubbering sound. If its too rich the saw will run at a lower rpm and cut slower. Too lean and the saw will scream and be lazy in the cut.

The saw should 4 stroke out of the wood and then ckean up in the cut..

Low end is adjusted so the saw has snappy throttle response. If your saw is too rich on the low end it will not idle very long as it will load up with fuel and stall.

Also make sure your saw is warm and you have a sharp chain while adjusting your carb.

Do a YouTube search for how to remove limiters and how to tune a chainsaw carb.

 

[Jrlh]

Just ran the first tank of fuel through it...Idles well no matter how ya turn it....Seems to have as much grunt in the wood as it ever did, ...Turned the high side up as far as it would turn with the limiter in place, seems to be acting as it should....It had me worried, the way it was acting right after the piston replace....But seems to have leveled out. Sure glad I tried again without taking it in....Thanks!