John Rainford

Not sure what happened to the photos, they uploaded okay and were there for a while and then disappeared. There is some grease inside the drum so I will remove all of that. I,ll check the oil pump. I will put the saw back together when I have some free time at the end of the week and see if I can upload a video. I did try the saw with a couple of different chains which I had sharpened and checked the raker depth. Chain sharpening does seem to be a bit of an art and although I don't seem to be able to sharpen to the level of a new chain, I can get them reasonably good. When I post the video I will show the chip size. Maybe this one will still be going on until 2021 spud.

Photos of my clutch and sprocket.

Oops, I misunderstood the 1,2,3, question. After reading your replies I took a close look at the clutch and sprocket as well as looking at a couple of videos of clutch and drum issues. The sprocket has two grooves on each arm, which have been cut in to it to a depth varying between 0.5mm and 1mm so I guess your theory of the chain slipping over the sprocket without engaging could well be correct spud. The springs on the clutch look good, they haven't eaten in to the metal as I have seen can sometimes happen. Not sure how to check the brake shoes, will look that one up. I will post some photo's of the clutch and sprocket later today. You never know you might have solved the issue for me.

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.

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.

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

Thanks for the replies. Yes I am an amateur and learning about 2 stroke engines as i go along. Amazing how many different things can go wrong with such a small engine. I think I will need to take it to a specialist , but I have some time and am going through all the parts carefully to make sure I didn't make an error when I stripped it down previously. So far I have checked the gap on the spark plug, the plug is wet and black, indicative I think of running rich. I have checked the gap between the flywheel magnet and the ignition coil. I have stripped the carb and checked the diaphragms are in the correct places and the right way round. The metering needle is at the correct height according to Zama diagrams and instructions. Used carb cleaner on the carb and checked the strainer wasn't blocked. I have washed and dried the air filter, sharpened the chain, checked the oil flow to the bar, cleaned the carbon deposits from the muffler and exhaust port. I Checked the fuel lines and filter for holes and signs of ware, same with the intake boot. I will remove the cylinder and check the seating of the baring seals, bearings are good. I will check the piston and inside of the cylinder, although from what I can see through the exhaust port they seem fine. I used JB Weld gasket sealer which is good for high temps and fuel resistant. If I don't find any issues after all this I will give up and take it to an expert who will probably diagnose the problem(s) in a few minutes.

This is a follow up to my post a few weeks ago which was about an ongoing flooding issue on start up. sometimes it would start and sometimes it would flood. I'm wondering if this new problem might give a clue to the issue. Once started it revs well, but when cutting, although it sounds fine, there is very little power and it takes four times as long as it used to when cutting a small log, and has no chance of cutting anything more than 10 cm in diameter. My brother used it to cut some small logs for the fire and used a tank of fuel in less than 15 minutes. I'm guessing compression issue, or maybe an air leak, but I am no expert. I would like to fix it myself and have stripped it down completely in the past so feel confident I could do so if I knew what the issue was. I was hoping not to have to pay out for compression and pressure/vacuum tests, but perhaps that is the only way forward.

Thanks Spud, I have been thinking that the compression may be low for a while now. I guess a compression test might be my next move. Do you or anyone else have any views on these cheap cylinders and piston kits from China. I just can't imagine that a cylinder and piston for less than £30 is of the quality needed for a chainsaw.

I posted here on another issue a few weeks ago and had some very useful replies so I thought I would do so again. I have a flooding issue on start up. My usual starting procedure is to put it in cold start, give it one or two pulls until I hear it trying to crank over, then move it to warm start and it usually starts on two or three pulls. However, after the carb screws were adjusted by a small engine mechanic, if it doesn't give me the cranking over sound after one or two pulls on cold start, it floods the engine and I can't start it at all. I took the plug out, it was very wet with fuel, and pulled the muffler which revealed a lot of fuel in the combustion chamber. Let it dry out over night and it started fine the next day. It is however, an ongoing issue, sometimes it will start and sometimes it floods. I'm wondering if the carb screw adjustment which was carried out resulted in to much fuel being sent from the carb to the combustion chamber, or perhaps there is another issue with the carb. I put a new carb kit in a couple of months ago, so I know the diaphragms are working. Could the metering needle be the issue? Any thoughts would be gratefully received.

It cuts straight and the chain is sharp. I don't have the easy start' on my saw so you can hold it at waist height and test the compression by holding the starter rope and letting it drop. It drops a little way, then holds for a few seconds, then drops a little again and then holds for a few seconds and then drops to the ground.

It cuts straight and the chain is sharp.

Cutting through some logs that were around 12 inches thickness the saw started getting stuck in the cut, ie there was not enough power to allow the chain to cut as it would normally do and it stopped moving. Small logs with less diameter were not a problem. I have a motorcycle repair shop opposite where I live so I asked them if they would do a quick compression test for me. It came back at 70. With what I have learnt from this web site I know that this is far to low for optimum power. So now I need to find out what is causing the problem. I have previously torn the saw write down for another issue which was resolved and the piston, crank arm and cylinder internals look good to me. The piston rings move freely and look fine and I made sure everything was replaced the right way round. Do I need to shell out for a pressure/vacuum test to get to the route cause or are there other things I could check first which don't need specialist tools. Any help would be appreciated.

I've been looking for an aftermarket carb to replace my Zama CIQ S119B, but despite a thorough trawl of the internet I could only find one that is in America. There are other models which are in plentiful supply that took exactly the same as the S119B on the outside, such as the S119C, but that's the outside, could the inside have a different make up ? Any ideas? The Stihl part number is exactly the same on both carbs 1139 120 0601.

After stripping down my saw, renewing the crank bearing seals, cleaning the carbon from the head of the piston and top of the cylinder, trying a couple of different spark plugs and fuel filters, I still have a saw that will sometimes start, run erratically for a minute, shoot out huge amounts of white smoke from the exhaust and then stall, so I am back to aquare one. I am thinking that the excessive smoking is a clue to what might be going wrong. I looked for a spark arrestor in the muffler, but it doesn't seem to have one. The muffler is the same as the one on the Stihl ms 181which is one complete unit, with nothing to take apart. So, what causes excessive smoking and rough running before conking out. Has anyone any ideas what I should try next. Maybe a carb clean/kit. Could my piston and cylinder be the culprit, despite cleaning the carbon from the piston top and cylinder top.

The pitting is all over the top of the inside of the cylinder, it's like little pin pricks all over the surface. The cylinder walls look fine, no scratches, no scoring. My new baring seals arrived today so I installed them. I couldn't see anything wrong with the old seals on inspection. However, the old ones slipped off the crankshaft with ease. The new ones were a much tighter fit. I did an experiment to see the difference between the old seals and the new ones. I put the old seal back on the clutch side and gave it a little squeeze. Squeezing it created a gap between the seal and it's seating. This didn't happen with the new seal, so I'm thinking the old seal has worn and no longer provides a tight air tight fit. I had an issue with putting the piston back in the cylinder. It didn't want to go in as easy as it came out. I made sure I had it round the right way, with the ring pins facing the carb. In the end I had to smother the cyllinder with 2 stroke oil and eventually it slipped in to place. I also got stuck trying to get the cylinder back in to the saw, until a little research showed me that it's much easier on this saw if you seat the cylinder base with sealant applied, on to the saw and then take the main part of the cylinder to the base. I was a little concerned that the gasket sealant was open to the elements for half an hour before pressing the cylinder parts together, but i'm hoping it's not going to be an issue. I used a sealant which is high temp, fuel and oil resistant. I did make one error, which was that I managed to snap the corner off one of the cylinder fins at it's base when trying to get it back in place on the saw. Next I have to decide between putting everything back together, checking the carb adjustment and firing her up or spending out on a compression/vaccum test. Any thoughts?

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?

Thanks Wedgebanger

Thanks for all the help. It was all very usefull. This is where I am with my first stripdown and repair. Everything removed down to the piston assembly. Clues as to the problem are as follows. Lots of excessive oil everywhere, especially around the clutch area. The crown of the piston was covered in a layer of carbon deposits which are black and smooth to touch. The top ot the inside of the cylinder was covered in a layer of carbon and is pitted underneath the carbon. One or two vertical scores at the exhaust port side of the piston. Crankshaft bearings look good under close inspection and rotate freely without any noise. Bearing seals look okay, but do have one area on each seal which is marked. I have cleaned the carbon from the piston and cylinder using a degreaser, but the pitting remains. I now need to decide how to proceed with the repair. I have ordered the seals at a cost of £4.50. I can get an aftermarket piston kit for £ 14 or a piston and cylinder kit for £ 25. Hutzl in China do the kit for £ 13 but are currently out of stock. High temp gasket sealer is about £ 6. Do I start with the seals and see if that works now that the carbon has been cleaned from the piston and cylinder, or do I jump in and do all of the above and hope I have sorted the problem. Any advice would be appreciated. Thanks wedgebanger.

Thanks for all the help. It was all very usefull. This is where I am with my first stripdown and repair. Everything removed down to the piston assembly. Clues as to the problem are as follows. Lots of excessive oil everywhere, especially around the clutch area. The crown of the piston was covered in a layer of carbon deposits which are black and smooth to touch. The top ot the inside of the cylinder was covered in a layer of carbon and is pitted underneath the carbon. One or two vertical scores at the exhaust port side of the piston. Crankshaft bearings look good under close inspection and rotate freely without any noise. Bearing seals look okay, but do have one area on each seal which is marked. I have cleaned the carbon from the piston and cylinder using a degreaser, but the pitting remains. I now need to decide how to proceed with the repair. I have ordered the seals at a cost of £4.50. I can get an aftermarket piston kit for £ 14 or a piston and cylinder kit for £ 25. Hutzl in China do the kit for £ 13 but are currently out of stock. High temp gasket sealer is about £ 6. Do I start with the seals and see if that works now that the carbon has been cleaned from the piston and cylinder, or do I jump in and do all of the above and hope I have sorted the problem. Any advice would be appreciated.

Stripping down my saw and have taken off the muffler, air filter and housing, carb, 4 Torx screws which hold the cylinder to the crank case, clutch and worm gear, flywheel and it looks like I need to remove the throttle linkage which appears to be stopping me lift the cylinder away from the crank case. I have watched some videos of other saws where you just pop the linkage from the handle and then pull it out at the end near the cylinder, but this one doesn't come out like that. Does anyone know how to remove it at the throttle trigger end? I tried to take the top of the handle off, but can't see any screws holding it on. Maybe it just pops off, but I dont want to force it.