MS261 Compatibility

[furb]

Today I got a nice 261 mtronic version two. Something came apart and took out the top end and left a bunch of junk in the bottom end. I have a few smashed version ones that have good top ends and cranks. Visually it looks like I can swap the top ends but I think I was told they don’t interchange. Both have the three bolt intakes. I recall there being different versions of intakes as well. I used to think I knew the difference but I can’t remember now. Anybody know what parts don’t swap? Thanks

 

[RI Chevy]

Depends if you have a 261cm Version 1 or Version 2.
Could you please post some photos of your saw. Makes it much easier than guessing.

 

[markds2]

Depends if you have a 261cm Version 1 or Version 2.
Could you please post some photos of your saw. Makes it much easier than guessing.

If you read his post Jeffus, he tells us that he is wanting to put a V1 crank and top end on a V2 saw. Unfortunately I don't know the answer. But I did read somewhere that it causes problems around the partition between the carb and cylinder. I guess one way would be to try and see.

 

[RI Chevy]

Sorry. I missed that.
Will not work. Cylinders are different.

 

[furb]

Would it work it I used the partition and intake from it? I’ll try and see before I split the case.

 

[RI Chevy]

No I do not believe so. Different cylinder design.
@drf256

 

[furb]

I can probably get the junk embedding the top of the cylinder out and get a new piston. Are the cranks the same?

 

[drf256]

I’ve been in both versions, but I don’t know what swaps out and what doesn’t. I can tell you what I do know.

The cases and cranks should be the same, but the V2 case is assembled with aluminum bolts that snap easily. Unsure why they went with these, as the weight savings are minimal from 5 bolts, but they did it. I use the same builder case to port V1 and V2 jugs, so both jugs will bolt down.

I believe the odd unidirectional base gaskets are the same. The pistons are the same.

The V2 has the tilted fins for weight savings. The V1 jug should bolt on and you should be able to use either intake.

I am told that the difference is in the partition to the airbox (the one the plug sticks through). Also possibly the top cover-I am not sure. I am fairly certain that if you have both parts saws there, you should be able to make something work.

OEM pistons for these are pretty cheap.

How bad is the damage? Any pics? Can the jug be fixed? What’s up with the crankcase, is it definitely fubar’d?

 

[furb]

The jug will be ok if I can get the debris that are imbedded in the top out. I have a good piston from the v1. The case is probably ok but I think the metal came from the bottom which is why I want to split it and may need to replace the crank. I think from experimenting last night if you swap cylinder, partition and cover you can do either way. I’ll get pics up later.