Modding MS260

[18 stoner]

Managed to get hold of a couple of second hand 260's the other day. The hope was to get one good saw out of the two, but turns out both are good enough to give a bit more servicable life.

The thought was to try and get a bit more torque out of one of them initially. Not really worried about modding an "old" saw on the grounds it may finish it off, as i still will have another, and, they really were not much money

So just wondering if anyone has tried opening the muffler on one of these little saws, are there any particular methods better than others, like what size hole should i go for on the outer case, should i scrap the inner baffle totally etc.

Cheers, Pete.

 

[Al Smith]

Well just keep in mind that we on this side of the big pond can do just about anything we desire to a saw .From what I read about GB ,you all are under some watchfull eyes . That said here's one method .

You want to crank the most power out with just a muffler mod then completely gut the baffles,screen and diverter if it has one .Install another hole or series of holes in the cover equal to about 75-80 percent of the area size of the exhaust port in the cylinder .Don't forget to retune the carb so you don't sieze the engine from running too lean .Because it will breathe better and thus move more air,it also needs more fuel . Now don't forget or in time you will in fact cook the piston and cylinder .

Actually you could leave the screen intact if you so desired . With just this little carving job alone it might wake that little saw up you don't want to do any more to it . Now it's going to get louder ,not unbearable though --usually .

 

[MasterBlaster]

I love an 026. It sounds like you lucked up!

 

[Al Smith]

They are neat little saws .

 

[sotc]

http://gypoclimber.com/showthread.php?t=11478&highlight=ms260

 

[Al Smith]

That was a good thread .In all seriousness though you don't need to cut raised dome pistons like Jay and I did .Oh sure they get the job done in grand style but most people don't have the facilities to do it .

A standard Stihl base gasket is 20 thou thick .If you cut one half as thick or ten thou you will raise the comp a tad . At the same time you've lowered your intake by ten thou .

If you did nothing more than bolt it back together at that point you will see some improvements if you did nothing else .

Now if you widden the ex port to within 40-50 less than the width of the piston piston skirt than did nothing but polished the intake ,you will see more improvement .At this point you have not changed your port timing except perhaps lengthening the duration of the power stroke because the ex will open later . The intake and transfers will still be pretty much stock .

What I just pointed out,anybody can do with nothing more than a file and some sandpaper .,no kidding .

What I'm trying to point out is you don't have to go to extremes like a few of us do to see improvements .Just a few basics but you have to build up your nerve to do the first one .After that it's smooth sailing .

 

[Al Smith]

Let me claify something in that last post.When I said 40-50 thou on that ex port .I meant leave than much on each side of the piston to assure the skirt seals .Some go less but I don't .Rather conservative ,ya know .

 

[woodworkingboy]

With Al's caution in mind about leaving enough material on the sides of the exhaust port, I'd widen to 65% of the bore, if allowable.

 

[18 stoner]

http://gypoclimber.com/showthread.php?t=11478&highlight=ms260

Sorry Willie, guess i should have used the search thingy before i posted the thread

 

[18 stoner]

Cheers you guys, all sounds good advise, i was initially just going to do the muffler mod as i have done a few of them but it sounds like just a little opening of exhaust port and a thinner gasket is worth a try.

Cheers again to you willie for the link, all i need to do now is read through, so bear with me, im not the fastest reader of info

 

[sotc]

No worries, I enjoyed the thread

 

[Al Smith]

Well 18 you aren't going to screw it up ,go for it .Get some juice out of that one and go on to the next ,maybe with some more moxie .

GB needs someone to get the ball rolling ,might as well you .