bmp01

The clutch cover might be the problem and you might have to get a known good one, one you know really belongs to a 024... But back up a bit, put the bar on the saw with out clutch cover (or chain). Can you confirm the collar on the bar stud below the surface of the bar ? If that's ok then take the chain adjuster out, it's not hard, then put the metal cover on. Can you see the thread on the bar stud continuing into the hole? (.....so the nut isn't bottoming on the stud before it clamps the clutch cover). If that's ok pop the nuts on and do them up. Still the same or fixed? bmp01

Owh hang on a minute... what's this in your picture? Is the tensioner holding the cover off ?

This is how the bar sits on the studs, note the collar is below the bar surface. Even then the clutch cover has 2 counter bores in it, so if the collar sits pround (above) of the bar surface it should still clamp.... If the above is ok then either, -the clutch cover is sitting on its outside edge, maybe it needs tightening down some more ? -the thread on the bar stud doesn't go deep enough so the nut is binding on the stud before it clamps on the cover, is the cover loose as well the bar ? HTH bmp01

Bar clamping info: Bar is 4.5 mm thick Stud collar height is 4.0 mm Tin plate is 0.5 mm thick This assembly does have a screw to hold the tin plate in place, studs screw down to saw body, so in this case the collar height is effectively reduced by 0.5 mm ----> bar 4.5 mm thick over collar height 3.5 mm.

Blimey this is getting a bit muddled. Couple of facts: 1) The location of the bar the saw case is 'roughly' located with the collar on the bar studs and the slot in the bar. This is not adequate for anything other than assembling the bar/chain and clutch cover onto the saw. 2) The side cover must clamp the bar to the saw for running purposes (and maintain chain tension etc). As mentioned hold the top of the bar up when the clutch cover is tightened down. Clearly something is not right with this saw. I've just pulled the clutch cover off my MS260, for a look see, taken some measurements and pictures.... all Stihl parts, just as it came out of the factory. First up bar stud collar and bar slot. ...

Looks like the clutch for dcs6000/6800 is obsolete but the drum is still available. .... didn't look too hard, part shop direct.co.uk Had me worried there.

That was worth a watch ? That guy should be dead by now.... staged or not.

Idles surprisingly well doesn't it.... Considering the high speed running I'm a bit surprised it doesn't just throw the towel in and give up. Probably just a fueling issue but I'd check the piston condition before running it anymore, (exhaust off, visual check through exhaust port). An outside punt, does chain run freely, chain brake is not clagged up ? Could explain why it idles ok but can't achieve a decent running speed. Edit: scratch that, looks like chain is running on at the end.

Did you spot that piece of plastic stuck in the reed valve , it isn't particularly obvious. Its the leg of the primer bulb. Saw would run on choke, not at all off choke and try as I might I couldn't see a problem with the carb. Checked for pulse signal for the carb pump - nothing, then we got there, the reed valve was blocked open. ....

Bought a Tanaka ECS 3351 yesterday, spare or repair . Plentyof compression but I had the exhaust off just in case - nice and clean piston. Rest of the saw was a little grubby but otherwise good condition, little used. Had the feel of being unused, 'parked' under the bench. ... Anyway reason for the post, slightly different 2 stroke design with intake charge controlled by a reed valve, don't see that to often in a modern saw and a then one of those 'Really !?! ' moments.....

To be honest I didnt have a scobby-do either .... I'm still bemused any one could chomp through or snatch up some fence wire and not know about it until investigating a running on chain. ... maybe someone else was to blame.

My money is on that. Either run on old pump grade fuel mix or the carb is gunked up. Lots to check, make sure you find something 'coz finding nothing is definitely the wrong answer.

I'm assuming the wire isn't a "design feature" but wrapped itself around the sprocket during a cutting incident. ... The chain running on being a result of the wire pressing on the crank and driving the sprocket (and chain) even when the clutch has disengaged. Happy to be told I'm wrong .... It'll all be fine in a bit though, the wire will soon wear to give running clearance and/or something else will break.

Giving the clutch a helping hand. ...

Oops.... Good inspection of chain required after that or is chain obviously fubarred? Was the "chain running on" the first sign of a problem ? No cutting issues up to then, no strange noises .....?... ???

Oh, ok, I'll go first. ... Other saw is a MS 192T and the box is cardboard like, crumpled news paper packing. And ermmmmm...... they need cleaning ? Nexxxttttt !!!

Here's another version, from a 021 parts list, L&S Engineers....

Private message sent to you regarding carb fix.

White smoke is usually associated with water (or coolant) going through the combustion chamber, not likely with an air cooled 2 stroke unless there is water in the fuel. But I'm guessing you changed the fuel for fresh mix when you did the fuel filter. ... I expect your white smoke is down to the 2 stroke oil you used during the rebuild, it's probably inside the exhaust and needs can good thrash to clean it out. That will have to wait. Have a look at this thread regarding carb problems : https://arbtalk.co.uk/forums/topic/111138-ms181-spluttering-and-bogging-down-at-high-revs/ HTH.

Piston is just as soft as the cylinder. So as Spud said if something has gone through the engine you'd expect to see a damaged piston too. So either piston has been replaced or it's a dodgy cylinder from the off. Could be aftermarket parts, do you know the saws history? Regarding assembly issues - the need to assemble the engine lose and bolt it all up in situe is a truely shite idea. I don't have any respect for Stihl for employing this design. Compound that with making it almost impossible to position the engine in the saw body.... just stupid. I've done a few now and it's not easy, best way I've found is to have the engine upside down and position the body over it. Well, the truth is you're not expected to rebuild these saws. Personally I'd just run it, you've changed and/or inspected all the bits that leak. If it's an old saw expect the carb to be a pain. ... bmp01

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).

Saws in bits already. ...

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. ...

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.

If you look from underneith, you'll see a slot at the operator end of the handle. The top cover has a clip with a barb on it which you can access in that slot. Flat blade screw driver in the slot to release the clip. Be super careful with the front end of the cover, there's a stupid flimsy piece of plastic ...