Stihl MS211/C problem with power in the cut

[spudulike]

The clam should use a flexible liquid gasket and not JB epoxy weld, it may do the job for a while but isn't the correct material.

[bmp01]

3 hours ago, spudulike said:

The clam should use a flexible liquid gasket and not JB epoxy weld, it may do the job for a while but isn't the correct material.

Chap said JB Weld flexible gasket. Looks like JB Weld are putting their name to a few other products these days, flexible gasket should be ok providing its compatible with fuel. 

[spudulike]

OK, if it is a RTVS jointing compound, it should be OK.

[John Rainford]

I'll take a look at the second butterfly and check that, thanks. 

 

Butterfly is operating fine. I took the cylinder out to inspect it and the piston. I checked that the piston had been inserted the correct way round, which it had. The ring pins were facing the carb side and were intact, as are the rings. I made sure the rings were the right way up, which they would be because i have never removed them from  new. The rings move freely.There are a few very tiny hair line scores on the exhaust side of the piston and even smaller ones on the cylinder wall. On the top of the piston it has a dark brown patch covering about a third of the surface area. So I now have it more or less completely stripped down. I solved my flooding issue with a slight adjustment of the metering lever about .5 of a mm. The saw now pulls over and starts every time. One more problem to solve, why is there no power in the cut despite the saw reving well ? I checked the bar for chain movement in the groove, there is a little movement but nowhere near as much as I have seen on bad bars on you tube. There was a slight ridge on each side of the bar at the top of the groove, particularly in areas where pressure would be on the bar during cutting. I filed these down, but it didn't solve the problem. The J.B. Weld gasket sealer I used is fuel and oil resistant and high temp resistant to 500 degrees. My lack of experience does not allow me to determine if the piston and cylinder are damaged to the point of affecting compression , but I watched a good you tube video on piston damage on Steve's Small Engine Saloon and another by Donnyboy 73 and mine are nowhere near as bad as any of the ones on the videos. I can get a cheap piston and ignition coil on e bay for a total of £ 15 and I'll get some Dirko Red gasket sealer just incase the J.B.Weld wasn't correct as Spud pointed out. I know it could also be a carb issue. Not sure why, but you can't get aftermarket Zama CIQ S119B carbs, and I am not going to pay over £ 80 for a Stihl one. I'm treating this as a kind of hobby, so don't mind spending a lot of time and a little money on it. As usual, any thoughts will be gratefully received.

 

 

[spudulike]

One of the first things that should be done is a compression check as without it, you don't know what you have got and if you change the piston, how will you know if it has improved the situation at all - it will probably reduce the compression until run in. You are probably changing the coil and piston for no reason bar that the may possibly be an issue and most likely changing them with inferior quality aftermarket parts dubious manufacturer.

I have had a couple of saws where the bore ended up being very slightly oval, one had the piston fitted round the wrong way round and forget the other but I simply couldn't get the compression up to decent levels so the saws were hard to start and lacked any power. The only solution was to change the cylinder on these. A very unusual fault but it does happen and the compression gauge told me a story!

Compression and carb issues must make up a good 85-90% of issues in bad running saws, coils very rarely fail and if they do, you can get total failure, failing after a period of use or just the old limited revs failure where the saw won't rev up properly.

I appreciate you are trying but the way you are going, your saw will be like triggers broom, you will have nothing left on the saw that is original and will have spent a fortune on it.

Glad you sorted the flooding issue, the metering arm is the usual place to check along with the diaphragm on older machines.

When you say the machine lacks power: -

1) Does the chain stop in the cut AND the revs die to the point of stalling

2) Does the chain continue to run at high speed and the saw revs high but doesn't cut

3) Does the saw rev high but the chain speed slows right down in the cut

Be careful in answering the above because each has its own set of faults that will cause the symptoms.

I can sort of see why you are doing this but despair about where it may end up.

Diagnosis is a precise skill, some people have a shotgun approach, I prefer to align myself with the American Sniper, one shot, one part, one fix! I guess it is why people like what I do.

PS - If your JB is a rubbery compound, you are fine, if it is grey and rock hard like a grey araldite, you have cocked up.

Edited January 15, 2020 by spudulike

[John Rainford]

Thanks for your info spud. Wise words from an expert as usual. The compression test is obviously a must and your line about inferior parts resonated as well. So I will take your advice and keep my original parts until the culprit is found. The JB Weld gasket sealer is a rubbery type substance which says that it is high temp, fuel and oil resistant, so maybe that was okay. In answer to your questions.

1. The chain starts to cut and will go in to the wood a couple of centimetres. At this point the chain tends to stop running, but the engine doesn't die, it still sounds as though its operating well.

2.  The chain does not continue to run at high speed. Although the engine is running and sounds good, the chain stops moving in the cut. If I lift the saw away from the cut, the chain will start to run again.

3. The saw revs high in the cut, the chain slows down and then stops altogether, although the engine is still at high revs. 

[NFG]

"The saw revs high in the cut, the chain slows down and then stops altogether, although the engine is still at high revs.  "

 

Would that be the clutch slipping then? would have thought it would be smoking though holding revs.

[bmp01]

49 minutes ago, NFG said:

"The saw revs high in the cut, the chain slows down and then stops altogether, although the engine is still at high revs.  "

 

Would that be the clutch slipping then? would have thought it would be smoking though holding revs.

Sounds like it or the sprocket is so completely trashed the chain is slipping over (or through) the teeth. Either way it doesnt sound like an engine problem.

 

Edited January 16, 2020 by bmp01

[bmp01]

5 hours ago, John Rainford said:

Thanks for your info spud. Wise words from an expert as usual. The compression test is obviously a must and your line about inferior parts resonated as well. So I will take your advice and keep my original parts until the culprit is found. The JB Weld gasket sealer is a rubbery type substance which says that it is high temp, fuel and oil resistant, so maybe that was okay. In answer to your questions.

1. The chain starts to cut and will go in to the wood a couple of centimetres. At this point the chain tends to stop running, but the engine doesn't die, it still sounds as though its operating well.

2.  The chain does not continue to run at high speed. Although the engine is running and sounds good, the chain stops moving in the cut. If I lift the saw away from the cut, the chain will start to run again.

3. The saw revs high in the cut, the chain slows down and then stops altogether, although the engine is still at high revs. 

John - regarding compression test,  in your previous thread you confirmed - the crude hang it from the starter cord test ....the saw dropped and nearly stopped at each compression stroke. Ok, its not precise but it confirmed compression isn't too bad.

I think Spud was offering multiple choice type questions, but nevertheless you're one step further on. Got any pictures of the clutch drum? 

Edited January 16, 2020 by bmp01

[NFG]

1 hour ago, bmp01 said:

... or the sprocket is so completely trashed the chain is slipping over (or through) the teeth. Either way it doesnt sound like an engine problem.

 

Oh yes, that would be a sorry sight!