Philip Osborne

OK, thanks for that, I will try the A4 paper gapping and see if it improves things.

What is meant by 'tiered' is it to do with the strength of the magnet?

Would you believe it, if I pull the starter ridiculously fast it sparks, anything less than that and there is no spark at all. Whether I can pull it that fast to start it under compression with the spark plug in position remains to be seen. Thanks again for the helpful suggestions from both of you, I find these forums are very helpful.

Thankyou for this information. The new ignition module was the genuine Stihl part complete with HT lead. I used a thin business card (.00115") to gap the coil from the flywheel. The magnets on the flywheel are surprisingly strong and I have cleaned them thoroughly. I have added a separate earth from the coil to the engine. I will go and try it again in the garage in total darkness, giving it a hefty pull like 'Openspaceman' suggests. Although looking at the video's on Youtube, the operators didn't seem to pull the starter chord excessively hard. I'll let you know what happens......

I don't think so, I've been pulling the pull cord quite quickly with no plug in, so it has been turning over very fast.

I have recently acquired a Stihl MS181 chainsaw that is is approximately 4 years old. I was advised by the previous owner that this chainsaw hasn't worked for the last year. I have been online to familiarize myself with the technical details of this saw and have made a start at trying to find out why the saw doesn't work. First I checked for a spark and there was no spark, so I replaced the plug for a new one of the correct type, still no spark. Then I replaced the ignition module with the correct Stihl replacement and set the gap between the module and the flywheel to the correct amount, still no spark. I have tried it with and without the positive wire connected to the coil, just in case it was a fault in the wiring harness. I have even tried it with an extra earth wire, in case the coil isn't earthing properly, still no sign of any spark. I have even tried it by holding the plug to see if there was any kind of electric shock, but there was nothing. I am at a loss as to what to try next, given that this is a very simple engine, with a basic ignition system. Any help would be greatly appreciated.