Ms260 Rebuild by a beginner

[Basher]

 

[pwheel]

If you find aluminum bits in the bottom end, consider splitting the case and replacing the main bearings & seals. Otherwise, the bits might trash the bearings and travel up into the top end and do the same there. Been there; ruined that.

 

[Swizzler]

Hey Tinkerer, I'm also working on my first attempt at a rebuild. I did an old 028 WB my father in law gave me.
Now I'm just trying to figure out why it stopped running

Good luck to you! I'll be following along.

 

[Wonkydonkey]

 

[Tinkerer Carver]

We are here to help. Personally have done a few of them 026/260’s.

Which parts do you have? Looks like a 44mm top end to me. I’d use that jug cleaned up, you won’t get the same performance from an AM P&C set. Meteor pistons are fine. That broken fin won’t do a thing.

Do you definitely have a carb with 2 adjustment screws? They came both ways, and IIRC only the Zama has an adjustment limiter. Never seen one on a Walbro on the 1121 model.

If you plan on working on saws, a vacuum and pressure testing tool is a must. In general. A small air leak will result in issues with keeping idle stable. You’ll chase it forever.

You are really forced to go through everything because the saw scored in the first place. Invest in a new oem fuel line and filter and a new oem impulse line. Carb needs to be gone through as well, may as well rebuild it in case there is an issue with fuel supply with the carb itself. The screen may be caked with the debris or there may be a metering issue.

The 1121 is one tough little saw. The bearings are oversized and usually last a very long time. If there is no radial play and they look good, you can probably get by with leaving them alone. A case split may be more than you’re up for at this point.

I know it sounds like a lot, but you can do it.

I’ve got the tune up kit, ignition coil, new intake manifold boot, and a complete gasket set. Also bought a piston ring compressor and piston stop kit. It has a Walbro carb with two adjustment screws.
I guess I will order an impulse and fuel line along with a vacuum tester. So far, the crank feels like it rotates well and I don’t see any off kilter wear. And you are correct, a case split does seem a tad intimidating at the moment

 

[Sagebrush33]

Hey Tinkerer, I'm also working on my first attempt at a rebuild. I did an old 028 WB my father in law gave me.
View attachment 294365 Now I'm just trying to figure out why it stopped running

Good luck to you! I'll be following along.

Welcome Swizzler.
I think the problem with your 028 is it's ashamed of it's colors.
It'll run great..... back to orange and white.

 

[Tinkerer Carver]

We are here to help. Personally have done a few of them 026/260’s.

Which parts do you have? Looks like a 44mm top end to me. I’d use that jug cleaned up, you won’t get the same performance from an AM P&C set. Meteor pistons are fine. That broken fin won’t do a thing.

Do you definitely have a carb with 2 adjustment screws? They came both ways, and IIRC only the Zama has an adjustment limiter. Never seen one on a Walbro on the 1121 model.

If you plan on working on saws, a vacuum and pressure testing tool is a must. In general. A small air leak will result in issues with keeping idle stable. You’ll chase it forever.

You are really forced to go through everything because the saw scored in the first place. Invest in a new oem fuel line and filter and a new oem impulse line. Carb needs to be gone through as well, may as well rebuild it in case there is an issue with fuel supply with the carb itself. The screen may be caked with the debris or there may be a metering issue.

The 1121 is one tough little saw. The bearings are oversized and usually last a very long time. If there is no radial play and they look good, you can probably get by with leaving them alone. A case split may be more than you’re up for at this point.

I know it sounds like a lot, but you can do it.

Also, on the condition of the jug. The OEM jug for this one is a Mahle and I had thought it would be scrapped because of the piston scoring, but I looked at it again last night and I think it’s saveable.

 

[Swizzler]

back to orange and white.

Ew. She should be ashamed. Sadly, the paint job is probably the highlight if my work. Lol.

 

[Chainmale]

A service manual is handy, you should be able to get someone here to send one to you. Have you done some dremmel work to the intake?

 

[smokey7]

Is that a pipe plug in the decomp hole?

 

[Spladle160]

That jug definitely looks serviceable. I would stick a good meteor piston and caber rings in it, replace the previously mentioned common wear/air leak items of the impulse line, fuel line and intake boot, rebuild the carb and vacuum/pressure test it. This would be a good chance for some basic performance modifications if you were interested like deleting the cylinder gasket assuing it leaves enough squish, advancing the timing, and opening up the exhaust a bit or at least matching muffler gasket and inlet to the exhaust port outlet. And remember it's just a saw and you have plenty of "help"

 

[Spladle160]

Is that a pipe plug in the decomp hole?

Sure looks like one... and that would definitely not be the right threads. That cross thread would be a very likely place for a small air leak.

 

[Swizzler]

I guess I will order an impulse and fuel line along with a vacuum tester.

I'll have to get one of these vacuum testers as I suspect my issues are impulse or fuel related.

 

[stretch5881]

I like it, jump in with both feet. I have seen pipe plugs like that with metric thread also. Might be?

 

[smokey7]

Looks like a 1/4 npt pipe plug to me. If they tapped the hole correct it could work I guess

 

[drf256]

Also, on the condition of the jug. The OEM jug for this one is a Mahle and I had thought it would be scrapped because of the piston scoring, but I looked at it again last night and I think it’s saveable.View attachment 294392View attachment 294393View attachment 294394View attachment 294395

Looks like a 44.7

 

[merc_man]

Subbed.
This may be a good time to invest in a mighty vac presure/vac tester.

Sent from my SM-G950W using Tapatalk

 

[Sagebrush33]

Subbed.
This may be a good time to invest in a mighty vac presure/vac tester.

Sent from my SM-G950W using Tapatalk

Whoa.... new avatar. I almost didn't recognize ya.
I was fond of your old one. LOL

 

[Tinkerer Carver]

A service manual is handy, you should be able to get someone here to send one to you. Have you done some dremmel work to the intake?

I may have played around with my dremel when I thought I was going to scrap it. Really I just took off enough to make the whole port shiny and practice technique

 

[Tinkerer Carver]

Is that a pipe plug in the decomp hole?

Not sure. I’m just gonna leave it be until I have reason to otherwise