MS261 M-Tronic Build

[Heavy Oil Saw]

In the lock down situation the country is experiencing at the moment, thought I’d get the project moving, and here it is, pretty cack handed and bodged together, but looking OK.

The book said 10Nm for crankcase bolts, but the kit instructions said 3Nm and 90 degree turn, so I went with the kit destructions.

It’s a 261 carb case, and I have an M-Tronic get up, so came across this problem

 

The M-Tronic coil was hitting this guide, which in turn allowed the flywheel to foul the pick-ups. Soooo, in great heavy handed fashion.......

Almost there

And finally pulling 150ish PSI, I was slow getting the camera, and my tester must leak. Oh, and there’s spark as well.

Thank you to people who’ve answered my questions, and to the forum in whole for info, been lurking about reading about tapping the ends of the crank and helpful tips like that. Honed the cylinder with 1000 grit and 2 smoke oil as lube, worked a treat.

Most of the parts are 2nd hand, cleaned in works parts washer and cobbled together by me. Hats off to you small engine guys, it’s fiddly as ****, and big hammers won’t achieve the desired effect as on heavy plant.

Last final part is getting the clutch and chain lube side sorted and then run it up.

[Dan Maynard]

Kitchen table? Good stuff.

[Heavy Oil Saw]

Kitchen table? Good stuff.

Kitchen island, I’ll have you know [emoji1787]. It’s closer to the kettle in there, and my work oven.

[Heavy Oil Saw]

Sat in bed, watching the news, and thought to myself, those pipes will cause you nothing but problems once you get the Aspen in, best run down, strip it back, order the hoses and wait. The carb can wait, that’s easy to get at.

Upgraded the solenoid to the white one, and the orange mesh filter though, just as a precaution.

Edit:- Yes that is a tea spoon, great tool for hoses and leverage, no sharp edges and thin.

[Ratman]

Keep us posted!

[Heavy Oil Saw]

@Ratman Only thing that’s worrying me is clutch side crank bearing, I’m sure it did something when I reheated the case half and fitted the crank. It isn’t interfering with the bottom end or the oil pump. I’ll let you know when it drops it’s guts on start up (if it starts up).

[peatff]

I'd have taken the corner off the cdi bracket on the bench grinder instead of grinding the case, but that's neither here nor there.

[Heavy Oil Saw]

I'd have taken the corner off the cdi bracket on the bench grinder instead of grinding the case, but that's neither here nor there.

On the damaged M-Tronic case, it’s that part that’s been modified, so I followed Stihl’s way of doing it. Didn’t want to mess with the coil.

[Heavy Oil Saw]

Pulled the jug off, again, anyone got a good idea about “free play” in the piston and crank. Got no vertical play, but some horizontal play in piston and crank.
I believe this is acceptable, but in what measurement?

[spudulike]

There should be no "up and down" movement in the piston to crank but there is always a slight movement side to side piston to con rod and around 2mm each side of the rod to the crank lobes at the big end.....if I am understanding you correctly. This float is perfectly acceptable whereas vertical movement shows wear in the ends, gudgeon pin or crank bearings.

The crank shouldn't move in the cases on this saw. They will on MS200s and similar as the bearings are a needle type allowing for some end-float and not roller bearings which hold the crank in place.

Edited March 29, 2020 by spudulike