Stihl ms 211/ c throttle linkage removal

[John Rainford]

Thanks Wedgebanger

[EricBradley]

If there is excess oil around the clutch area I would see what the housing is like, these saws have a tendency to wear away the casing and break through to the oil pump channel so when its running its pumping a little oil onto the bar and a little oil on into the clutch.

[bmp01]

It's a bit difficult for peeps to comment on a problem when there's not much info to go on.

What exactly was the problem that caused you to pull the saw apart ?

I'd expect there to be an oil film inside the engine,  especially if it wouldn't start and/or has been "cranked" lots with the choke on. It's typical of 2 stroke fuel to evaporate the petrol and leave the oil behind. ..

Similarly, carbon on piston and combustion chamber is normal, within reason.

And what is pitted? If it's the combustion chamber, after you've cleaned the carbon off - are we talking about the cast surface? That's normal.

If the original piston and cylinder are genuine parts, they need to be wrecked before its worth looking at inferior aftermarket parts.

 

Post some good pictures.

Edited April 22, 2019 by bmp01
Missing word added

[John Rainford]

The reason I am stripping the saw down is to find what is causing it to conk out soon after starting, only starts on cold start and engine reved extremely high without me touching the throttle. I didn't attempt to start it again after that. I have to admit that I can't post pictures because I don't have a good enough phone to do this. 

Since my last posting I have got interested in the workings and problems with stihl chainsaws and am now not sure that I need to purchase a new piston and cylinder. i have learnt that a layer of carbon on the piston head is fairly normal and the pitting on the cylinder head may not be a big issue, although does indicate a possible fuel/air mix problem. I am now thinking that I have an air leak somewhere. I have checked the intake boot and it is fine. I have ordered new crank seals and will be replacing the gasket sealer in the cylinder. I now realise that the saw needs a pressure/vacuume test to see if it is an air leak. I will pull out the fuel line and check that because it's stripped down already. Anywhere else to check before it goes for a vaccume test?

[peatff]

First thing to do would be to check the H & L screw by screwing them in till they seat gently then turn them out 1 full turn each then try to get the tick-over fairly even when you have warmed up the saw.

[bmp01]

26 minutes ago, John Rainford said:

The reason I am stripping the saw down is to find what is causing it to conk out soon after starting, only starts on cold start and engine reved extremely high without me touching the throttle. I didn't attempt to start it again after that.

Right, that's a decent starting point. 

So this is the normal starting procdure (below), can you confirm at what stage your saw revved up "extremely high" ? This might help people to offer advice. 

1) cold saw, so set to choke position, saw cranked, saw coughs at this stage,

2) control set to fast idle, saw cranked, saw starts and revs high (assuming chain brake not applied),

3) throttle trigger squeezed momentarily to disengage fast idle, saw should idle.

 

Your air leak diagnosis could well be right, certainly if the saw revved madly while on choke (1 above).  It'll be a big air leak in that case, inspect parts and replace as you are doing.

 

The only example I can think of where this happened was with a MS181 where some of the screws - engIne to saw body came loose. These screws double up to hold the two halves of the crankcase together (clam shell engine) so the air leak was where you have the liquid gasket. There was a lot of grey paste from worn aluminium. ...

 

 

[bmp01]

6 minutes ago, peatff said:

First thing to do would be to check the H & L screw by screwing them in till they seat gently then turn them out 1 full turn each then try to get the tick-over fairly even when you have warmed up the saw.

Saws in bits already. ...

[Wedgebanger]

Yah, when you re assemble it a pressure & vac test is needed. And remember to rotate crank to see if it holds the p&v.... then on to the next part of a rebuild, get it to run and tick over, then rev smoothly  up to max revs.... also that means a play with the carb. Oh those carbs can be finicky things to tune...??

[spudulike]

Just post some photos. Pitting on the combustion chamber tends to mean metal fragments have been smashed repeatedly between the piston and squish band but the piston would also have damage in this instance. It is most likely your description may be a bit off and a few photos will clarify.

The clutch oil leak - may be fuel oil residue from a badly leaking seal (if black) unless the oil is clean chain oil from other sources.

[bmp01]

9 hours ago, spudulike said:

Pitting on the combustion chamber tends to mean metal fragments have been smashed repeatedly between the piston and squish band but the piston would also have damage in this instance.

Replacement piston? Saw history.

My punt - it's the roughness of the cast surface compared with smoothness of machined surfaces. 

 

Mr Rainford, is the squish band in the cylinder pitted ? (Squish band is the 2-3 mm wide ring around the periphery of the combustion camber).