Cannot start MS260

[ErnieG]

Looks like it's been out quit some time judging by all the build up on it .

Ernie

 

[cookies]

Looks like you found the root of your problem, get that cylinder off and lets see if it is salvageable. I would put a drop of blue loctite on all 4 cylinder head bolt during assembly, being previously left loose those bolts hammered the threads in the case. I would also be likely to check every easy access case bolt for proper tightness and if any are found loose I would check every one.

 

[SteveSr]

It fell down when I removed the exhaust can. I thought I was having trouble with my adding for a moment - two holes, 3 bolts?

Definitely looks like a cylinder bolt!

BTW, what model carb is on that saw? If it has a non-adjustable "H" you might want to consider replacing it with a fully adjustable one and doing a muffler mod as well.

 

[deanbrown]

Here’s a few pics

 

[deanbrown]

 

[lone wolf]

View attachment 1148421

Did you check the hole in question to see if the threads are still good?

 

[deanbrown]

Did you check the hole in question to see if the threads are still good?

Yes, it's A++, no different from the others.

 

[lone wolf]

Yes, it's A++, no different from the others.

Try some muriatic acid on the transfer, but first look up videos on here about how to do it properly.

 

[lone wolf]

Here is Masterminds video on how he does it !

https://www.arboristsite.com/threads/show-us-your-cylinder-cleaning-tools.368676/

 

[SteveSr]

Yes, it's A++, no different from the others.

That's a LOT of transfer on the exhaust side and the worst is right next to the port edge where acid WILL ruin the cylinder if it gets there.

Anyone have any tips for keeping the acid away from the port edges if the OP decides to use acid?

I would almost start with 80-100 grit by hand keeping pressure away from the port edges.

 

[TNTreeHugger]

I'll bet if you had taken it to a shop seven days ago, it'd be up and running by now.

I know, this is more fun.
Carry on.

 

[cookies]

That's a LOT of transfer on the exhaust side and the worst is right next to the port edge where acid WILL ruin the cylinder if it gets there.

Anyone have any tips for keeping the acid away from the port edges if the OP decides to use acid?

I would almost start with 80-100 grit by hand keeping pressure away from the port edges.

I'd rub it with 200 grit to start then scotch brite, rub alittle grease in the port if scared. Use acid on a dipped Q tip and apply lightly to the transfer then count to 20 and dip in a bucket of water to neutralize, start over with 320 sandpaper, scotchbrite then acid. If I find a pit or scratch in the plating while using my method Its typically before the acid reaches it because my method is pretty slow going.

 

[stihltech]

Now you have a diagnosis. Nothing new on the bolt being out. See it occasionally. Check all bearings for looseness and cages intact.
Replace the gasket, remove the transfer, clean the cylinder up with you choice of glaze breaker, fine sandpaper, etc. New piston.
The next bet is the seal under the flywheel. Replace more of those than any other on saws.
PLEASE no aftermarket rubber parts! Sick of diagnosing saws with fuel hoses and filters that will not pass fuel.
And do not forget to verify the fuel tank vent is open.
Now we await results

 

[Sidecarflip]

OP said he didn't use it a lot in the beginning, spent most of it's life just sitting.

 

[deanbrown]

Can you guys recommend me where to get Stihl parts from? My nearest service center is a good 40 min drive so if I can get them online it would be good. I know ebay does sell some oem stuff but is there a better place?

 

[EchoRomeoCharlie]

I personally wouldn't buy parts online for a saw I need. For a fun saw, sure.

You can call the Stihl dealership and order the parts over the phone and only have to make 1 trip to get the parts. I have had a dealership I worked with a lot ship me parts when I was out of town and needed some stuff....I don't know if that's something a lot of dealerships will do or not...but maybe ask them. Obviously you will have to cover the shipping.

 

[markle]

I find lately, especially husky, getting parts from dealers and the mfgr warehouses takes weeks, often months. I look up part numbers online, and often go to eBay searching on the mfgr part numbers and make and model saw. I get oem parts much faster this way. If you’re not in a hurry, dealer it is, but they still make me pay for parts before they order. MS260 was popular and a good saw. Lots of parts out there. Minimally, it appears you will need the piston/ring/wrist pin/circlips and cylinder base gasket. that crank seal under the flywheel is a common failure, but it can be replaced from outside the Crankcase…no need to split open the crankcase for that one. You’ll know right away from pressure / vacuum test…or just replace it Since you’re this far into it. Once parts on order, work on cleaning up the cylinder, removing the aluminum metal that came off the piston from the overheating event. Thanks for your patience here. Lots of sound advice from people who hate to see saws on junk piles.

 

[Bob Hedgecutter]

Can you guys recommend me where to get Stihl parts from? My nearest service center is a good 40 min drive so if I can get them online it would be good. I know ebay does sell some oem stuff but is there a better place?

Do you know what you need to order yet to do an online order?
Personally I would buy a gasket set that included the main oil seals (cheaper here than buying the seals alone) and it gets you a new cylinder base gasket as well.
I would clean up and inspect the transfer out of the cylinder and if it passes- compile a parts needed list with the help of others here.

 

[Mad Professor]

That's a LOT of transfer on the exhaust side and the worst is right next to the port edge where acid WILL ruin the cylinder if it gets there.

Anyone have any tips for keeping the acid away from the port edges if the OP decides to use acid?

I would almost start with 80-100 grit by hand keeping pressure away from the port edges.

For the acid to work you need to first get any oil off the transfer, the acid won't work on oily surfaces.

I use a coarse wet/dry and dish detergent first, rinse it. You can protect the port edges by first drying off the cylinder then applying some grease on them with a q-tip. The acid won't get under the grease.

Go slow with the acid as mentioned using a q-tip. Have water and baking soda solution to rinse with/neutralize the acid. Also for safety and spills. Wear gloves and safety glasses.goggles. If you get any on the ports/edges rinse immediately. After a rinse use the wet dry paper again and see what's left. Then start over with the grease first, ..........

You will actually see the acid dissolving the transfer and it may bubble a little. Wait till bubbling stops before adding more acid.

Good luck and post pictures as you remove the transfer.

 

[Chevboy0167]

Part numbers help......

https://cdn.imagearchive.com/arbori...61716113b26530df5d93fc536efab33376cbac529452e