Stihl MS261 backfiring, running backwards and generally misbehaving

[spudulike]

I reckon you probably have a Flywheel part code  - 1141 400 1200

If so, you need a coil part - 1141 400 1302

Post your flywheel part code when you have it if it isn't this - do you have your existing coil part code?

[gand]

This is what I've got from your s/n.

 

 

[AWG81]

Great, thank you. I'll take the flywheel off tonight and check the part number. The only number I can find on the original coil is: 1106 0 621 which I think is for the rubber spark plug boot at the end of the lead. Should there be a number on the module itself? It just says ZhongfaTec. I'm wondering if this is non-genuine? Will report back later with flywheel info! Cheers!

[peatff]

3 hours ago, AWG81 said:

It just says ZhongfaTec. I'm wondering if this is non-genuine?

 

Looks like an Aliexpress seller so most likely a Chinese replacement coil.

[AWG81]

Ah, the plot thickens - the part code on the flywheel is: 1141 400 1220 B

 

Meaning, the saw probably has the incorrect flywheel fitted?

 

Is it a case of matching the correct ignition coil to the flywheel? Or is the timing out because of how the flywheel is orientated on the crankshaft?

 

Thanks for the help so far... 

[spudulike]

It is really difficult to tell, It would be unusual for someone to change the flywheel as it isn't the easiest of things to remove.

I would say that the coil failed or someone replaced it with some aftermarket coil that either isn't the correct one or is faulty. I once swapped out one on a strimmer and had a similar result and got a aftermarket coil but it was faulty and found the spark was around 180 degrees out. Started and run well with the correct OEM coil fitted.

I have pretty much drawn a blank on your flywheel part code bar this - https://www.zeichnung.ersatzteil-service.de/zeichnung-datenbank/1000293.pdf

How is your German?

This appears to list coils 1141 400 1302 & 1141 400 4702 but can't guarantee they would work but guess one or both will. 

Personally I would phone a decent parts suppler like L&S, state the flywheel number and see if they can phone Stihl UK and get the correct coil part code for your saw. They purchase direct from Stihl so can call on them for info like this.

One positive is that it looks like the crankshaft hasn't changed so that means if the correct coil for the flywheel is found, it should work.

BTW, L&S have been my supplier for around 10 years and always have been 100% in all my dealings with them.

Let us know how you get on.

[spudulike]

In addition to the above, I would also ask L&S to check that your flywheel is for the NON Mtronic model. It is possible that someone has fitted the Mtronic flywheel on it.

[AWG81]

Great, thanks Spud. I'll give L&S a shout today and see what they come up with. Will post back here.

[AWG81]

L&S have given me part number: 1141 400 1331 for the coil. The OEM part is £138 which a little out of my budget at the moment so this saw is going to have to sit on the bench for a while! Thanks all for the help, I will report back here when I get the saw up and running.

[Dan Maynard]

Hmm add in a carb kit and it's not going to be cheap job.