MS260 Piston Pin Circlip Killed Piston

[SteveSr]

When you have one of these grenade like this what is the best practice to clean the bottom end out. Piston aluminum might or might not be much of a problem depending on size but any errant pieces of the circlip would be.

What would be the advisability of pulling the crank seals to allow inspection and flushing of the crank bearings vs. splitting the case? And then there is the big end bearing that should be flushed. Any tips?

 

[KarlD]

Imo the case must be split, cleaned out and full inspection

 

[Fatherwheels]

Looks like the cylinder was off before, some marks on the bottom
of it that didn’t come from nowhere. No signs of heat, so your mix
was lubricating, still odd that the saw does look dry though, one would
expect traces of oil in the case, even on the piston sides.

The c clips seem to be aftermarket, not many use them as the Stihl ones
are way better, no one with any thought would scrimp on them, I would
say your saw would still be going if the clips had stayed in place.

Sure hope you get a decent saw builder to put your saw together again.

 

[Ricrhys]

Imo the case must be split, cleaned out and full inspection

I'll split the case, what parts will be needed if in an ideal world I inspect it, clean it out and all is ok, the crank seal Im guessing and what else?

I found a genuine Stihl set https://www.lsengineers.co.uk/cylin...stihl-ms260-ms260c-part-no-1121-020-1217.html
so I'll go for that if they can get them in.

 

[Ricrhys]

When you have one of these grenade like this what is the best practice to clean the bottom end out. Piston aluminum might or might not be much of a problem depending on size but any errant pieces of the circlip would be.

What would be the advisability of pulling the crank seals to allow inspection and flushing of the crank bearings vs. splitting the case? And then there is the big end bearing that should be flushed. Any tips?

Would definitely appreciate any tips on this!!

 

[KarlD]

I'll split the case, what parts will be needed if in an ideal world I inspect it, clean it out and all is ok, the crank seal Im guessing and what else?

I found a genuine Stihl set https://www.lsengineers.co.uk/cylin...stihl-ms260-ms260c-part-no-1121-020-1217.html
so I'll go for that if they can get them in.

2 crank seals
2 crank bearings
1 Crankcase gasket
Cylinder/piston/rings/wrist pin bearing/circlips
Oil pump gasket
Base gasket
Think that’s it

 

[KarlD]

That’s a good buy from LSE

 

[Ricrhys]

Thanks Karl, that’s exactly what I’m after.

I take you’re all in agreement it’s worth rebuilding as opposed to just take a punt on another on fleabay?

I’m not going to strip anymore until I have the right parts. I’ve cleaned it up as much as I can for now.

 

[KarlD]

Yes definitely split/inspect and rebuild rather than buy an unknown. The 026 is a great saw in it’s class. Keep the pictures coming as you progress

 

[blsnelling]

I see no reason to spill the case. Most wouldn't even remove the seals. Careful inspection and a flush should be sufficient.

 

[Patrick62]

I'm with Brad on this, if the bottom end is good, flush the thing, put new top end on it and run it like you stole it.

 

[dmb2613]

+3 on not splitting the case, wash it out good with the same mix you run in the saw, you can put seals in it afterwards if needed

 

[KarlD]

I don’t understand why you would choose not to split the case and do it properly. The only added cost is some time, a gasket and a couple of bearings and seals. All the money is in the top end. Just my 2p

 

[cuinrearview]

That's funny to me. Three years ago I had a 2149 that ate a circlip just like this and Brad was the first to say I should split the case.

 

[Ricrhys]

Hmmm decision time then, to split or not to split, I've ordered a genuine top end from a local Stihl dealer for the same price as L&S (support local and all that) and a new small end bearing and gasket from L&S, should all be here by the end of the week.

Can anyone shed light on why the bottom end would be dry?

 

[82F100SWB]

Most of the time a quick flush is all you need to clean out the bottom end. If you want to split it and make sure, it isn't going to hurt anything, but personally I wouldn't.
The bottom end looking dry is probably it being a bit lean on oil. I like to run fresh builds at 32:1, but I don't mix gas separately for them so everything gets it. Not a huge fan of 50:1, but it isn't the end of the world.

 

[Ricrhys]

Most of the time a quick flush is all you need to clean out the bottom end. If you want to split it and make sure, it isn't going to hurt anything, but personally I wouldn't.
The bottom end looking dry is probably it being a bit lean on oil. I like to run fresh builds at 32:1, but I don't mix gas separately for them so everything gets it. Not a huge fan of 50:1, but it isn't the end of the world.

Cheers for the advice, I've had a good clean out of the bottom end with a combination of fuel mix and compressed air (not at the same time). I'll be rebuilding it with an ex yamaha motorbike engineer so I'll trust his judgment on splitting and keep everyone posted.

 

[SteveSr]

Hmmm decision time then, to split or not to split, I've ordered a genuine top end from a local Stihl dealer for the same price as L&S (support local and all that) and a new small end bearing and gasket from L&S, should all be here by the end of the week.

Don't forget the 3rd option... pulling the seals is a great way to inspect and flush both crank bearings. At least, you'll be able to positively make sure that no pieces got on the seal side of the bearing. It all depends on how much use this saw has had whether or not the bearings are an issue. I would think probably not.

Pulling the seals might also be a good first step and depending on what you find you can make a decision to split the cases or not.

BTW, the gasket kit comes with the seals for less than the cost of just the seals.

 

[blsnelling]

That's funny to me. Three years ago I had a 2149 that ate a circlip just like this and Brad was the first to say I should split the case.

Now that's funny! Lol . I guess I'm getting lazy in my old age!

 

[cuinrearview]

Now that's funny! Lol . I guess I'm getting lazy in my old age!

Our opinions definitely evolve over time. I'm glad I took your advice.