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T i m T i m is offline
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Default Sthil ms260 rebuild

On Thu, 22 Apr 2021 16:45:50 -0700 (PDT), Chade
wrote:

On Wednesday, April 21, 2021 at 11:21:13 AM UTC+1, T i m wrote:
On Tue, 20 Apr 2021 13:48:55 -0700 (PDT), Chade
wrote:
Hi all

My sthil ms260 was starting fine but overheating and cutting out. My local garden machinery repair place told me it was because the piston/cylinder was scratched

Do you know how they knew that?


They said they had removed the muffler and so looked directly at the piston.


Ok. Did they give you it back complete and did you confirm the damage
when it was apart OOI?

and as this would probably have damaged the rod it was beyond economic repair.

'Probably'?


If you still have the old parts, can you feel any slack in the big end
bearing or gudgeon pin? If you hold the crankshaft still and the
conrod square to the crank, can you move the rod up and down at all
(in the same plane as the rod, not sideways or rock it etc)? If not
(and same with the piston to rod), you might not have needed a crank
if they don't come as one assembly (with piston etc) and maybe keep it
as a spare?

Knowing nothing about engines, but surprised by the cost of new chainsaws, I spent some time on google and youtube. I ordered a new crankshaft, piston, various bearings, gaskets and cylinder assembly.

Ouch (unless they were Chinese clones)?


Apart from one bearing they were third party at less than a third the cost.


OK, result. ;-)

snip

Are these 'plain bearings' (metal on metal) or 'open' (presumably)
roller or ball bearings?


Pin roller bearings. I guess they would be classed as open.


Yes, 'open' in that they didn't have seals and you could get grease on
them (even if only when out of the machine etc).

I know really I should take it all apart again to clean it and put it all back together, but if I started and ran the saw as it is and everything else was right would it do much harm?

The only place I can think of where you wouldn't want grease is on the
centrifugal clutch shoes and they are fairly easy to get to if you
thought there was a chance.


The clutch shoes are grease free.


Cool.

As newshound confirmed, the chances are any bearing in a chainsaw is
unlikely to suffer with (over/) greasing and if it's say on the big
end or crankshaft main bearings, are likely to be washed out with fuel
pretty quickly anyway (and why there is oil in the 2/ mix).

Well done for saving another otherwise 'written off' tool (we have
saved others similarly by mixing and matching 'broken' kit).

Cheers, T i m