MS251C gone hard to pull over

[Echo]

Make sure clutch is not binding and when you pull the cord your trying to drive

the chain, look nothing disintegrated in at the oil pump drive too.

Other than that, take off they cylinder, its dry looking in there, maybe carbon is on the move,

maybe you got a ring locating pin coming out, its better to look in there, when the cylinder is off

you can examine all, and see how the crank bearings are.

[petercb]

Thanks for all the replies.

Starter mechanism is working ok and not binding.

Chain brake is working ok and bar does not try to turn when starting everything seems to be working as it should.

Have just managed to spend a few more minutes looking at it and it seems a bit freer than before no funny noises or anything obvious binding.

Have out some WD40 in bore but this was after finding it had gone a bit easier to turn flywheel.

Clutch is free with no obvious broken springs but I can see what looks like a bright piece of wire underneath it between two segments, just visible in photo as bright spot sorry can't get a better photo. Not sure what it is but will take clutch off this evening and have a look. As I've said clutch springs look ok. Maybe somethings moved while I've been looking at it and handling it.

[spudulike]

The binding is either in the engine or external to it. It is possible the flywheel is contacting the coil or a screw has come out and is behind the fly wheel. It is also possible to be a clutch issue. 

I usually pull the clutch off and the recoil cover and then, with the spark plug out, see if the flywheel is easy to turn round or not and also feel to see if the binding gets better or worse at any point as this tells you something about the engine.

When was the saw last used? if it was months ago, the fuel in the cylinder will have evaporated leaving oil in the bore and this can make a saw difficult to turn over.

If the saw feels notchy then it may be main bearings, big end or small end. 

If the saw feels like it is locking up then pull the flywheel off and look behind it....I had a saw once where a screw had lodged itself behind the flywheel - felt terminal but was just fine once I had cleared the issue. 

[spudulike]

Looks like the oiling arm or "spring" as Stihl call them! Ref the pic!

[ChrisNewport]

on re assembly the oiler spring sits in the cut out in the clutch drum, the line on the top of the drum aids re- alignment

[spudulike]

The clutch springs look a bit slack, fair bit of rust around the shoes!

[petercb]

Thanks Spud checked clutch springs and coils are sitting tight together. Took flywheel and clutch off and all as it should be, no foreign bodies floating around. I did notice before stripping it further that it was generally freer which makes me think maybe there was something there which has dropped out or alternatively as you suggested the rings were gummed up. Have WD40'd it and have now rebuilt it and can pull it over and start it. It's still not easy but it has always been hard to pull over right from new, probably one reason why I don't use it as my main saw. Note to self never buy petrol chainsaw without decompressor! Will see how it performs over next week or so.

Anyway thanks to you for your advice and indeed to all for your helpful suggestions.

 

[spudulike]

The coils sitting tight is a sign the springs are a bit shot, for the sake of a fiver, I would swap them out....they won't get better!!

[petercb]

The coils sitting tight is a sign the springs are a bit shot, for the sake of a fiver, I would swap them out....they won't get better!!

As you say for a fiver will swap them out. Counterintuitive though all previous experience with expansion springs is they open up when failing which is why I thought they were OK.

[htb]

They wear where they hook round the clutch shoes, leaving thin spots on the springs, the tension comes off as the springs become coilbound. 

Very common on well used 200T