Stihl ms261 piston question (burned)

[MartDalb]

Check the kill wire first, make sure it's not going to ground along its length and check the switch is all functioning correctly. Use a multimeter

Yes.

I will dig into it tonite.
Truly hoping it is a faulty wire etc.

What am i looking for with My multimeter?
Have never had to test a coil.
Just switched them to other used ones, and in this case, I can't since I only have stuff for 260s etc.
Damn fancy new stuff....

 

[Vintage Engine Repairs]

Yes.

I will dig into it tonite.
Truly hoping it is a faulty wire etc.

What am i looking for with My multimeter?
Have never had to test a coil.
Just switched them to other used ones, and in this case, I can't since I only have stuff for 260s etc.
Damn fancy new stuff....

No no, you’re not testing the coil. That’s not possible in this case.
Find the kill wire on the ignition coil and disconnect it and attach one probe to it. Turn the switch on the saw to the run position and touch any metal part of the saw, try a few spots. If you are getting continuity you have a short to ground. Then you go hunting along that wire. If a wire is pinched and the sheath is frayed touching metal it’s going to ground.

The HT lead can also be jumping to ground too.

Clip one multimeter multimeter to the spark plug spring in the boot. The other to the cylinder fin. It should be an open loop. If you get continuity your HT lead is grounding and causing a loss of spark.

 

[MartDalb]

No no, you’re not testing the coil. That’s not possible in this case.
Find the kill wire on the ignition coil and disconnect it and attach one probe to it. Turn the switch on the saw to the run position and touch any metal part of the saw, try a few spots. If you are getting continuity you have a short to ground. Then you go hunting along that wire. If a wire is pinched and the sheath is frayed touching metal it’s going to ground.

The HT lead can also be jumping to ground too. Check both.

Thanks a ton. I Will get af it once these pesky Kids give me some peace!

 

[Vintage Engine Repairs]

Thanks a ton. I Will get af it once these pesky Kids give me some peace!

Have a re read of my post, I added to it about how to test the HT lead too. I got a saw out to test proof of concept and that what I had in mind was correct. It is.

 

[huskihl]

It’s not that it’s harder just different. There are more parts, that kill switch itself is a pain to get out. I put a piston in a 261 m tronic and cleaned up the cylinder and I’m sure it didn’t take 10 hours but it took a while.

No need to completely remove it. If you unhook the rubber support on the right hand side, there’s enough slack to get it off the carb studs and flop it over the left hand side

 

[MartDalb]

No no, you’re not testing the coil. That’s not possible in this case.
Find the kill wire on the ignition coil and disconnect it and attach one probe to it. Turn the switch on the saw to the run position and touch any metal part of the saw, try a few spots. If you are getting continuity you have a short to ground. Then you go hunting along that wire. If a wire is pinched and the sheath is frayed touching metal it’s going to ground.

The HT lead can also be jumping to ground too.

Clip one multimeter multimeter to the spark plug spring in the boot. The other to the cylinder fin. It should be an open loop. If you get continuity your HT lead is grounding and causing a loss of spark.

Did as you explained here.

Found no continuity on kill wire to metal and same with HT lead.

Any other ideas?

 

[MartDalb]

Ok... Pulled out the ignition coil.
Took off the boot.

Looks like this.

(edit) and ofcourse the coil wire is too short after correcting the damn spring/wire connection

(edit) This could be the issue though, that spring was no where NEAR the wire, see picture nr 2.

 

[MartDalb]

Nope, still no spark

Out of ideas now...

 

[MartDalb]

This looks like a new ignition module then? Which is insanely expensive on this version, sadly.

Any last minute ideas, ill take them!

 

[Oldsawnut]

Most coils the other end of the lead is just threaded into the coil so the coil end of the lead also needs checked.

 

[MartDalb]

Most coils the other end of the lead is just threaded into the coil so the coil end of the lead also needs checked.

Can you elaborate?

I reconnected the boot plug/spring with the coil wire.
I took off the wires, inspected them all. no signs of damage.

Retested with 2 different spark plugs, and no spark.

(edit) this part, red circle in pic? I took it out and sat it back tightly, no change.

 

[SteveSr]

Can you elaborate?

I reconnected the boot plug/spring with the coil wire.
I took off the wires, inspected them all. no signs of damage.

Retested with 2 different spark plugs, and no spark.

(edit) this part, red circle in pic? I took it out and sat it back tightly, no change.

If this is an M-tronic unit you might not get any spark if there is no continuity to the carb solenoid. See the computer is smarter than you are! It knows better thant to try to run when it can't control the fuel solenoid.

 

[MartDalb]

If this is an M-tronic unit you might not get any spark if there is no continuity to the carb solenoid. See the computer is smarter than you are! It knows better thant to try to run when it can't control the fuel solenoid.

Damn new fancy stuff!
Yes it is an m tronic.

Any advice how to test and possibly fix this?

 

[Vintage Engine Repairs]

Ok... Pulled out the ignition coil.
Took off the boot.

Looks like this.

(edit) and ofcourse the coil wire is too short after correcting the damn spring/wire connection

(edit) This could be the issue though, that spring was no where NEAR the wire, see picture nr 2.

It’s far from ideal in picture 2. The end of the HT wire should have the strands exposed and wrapping around the spring. That spring should be pushed right back too.

Either way this seems not to be your issue.

Don’t be too disheartened, this is all part of the “fun” of fixing saws or any engine. You have a good group of guys on the forum behind you.

My suggestion is to do a quick search for used ignition coils (OEM) and give it a go. You may be able to call your local Stihl shop and ask if they have an good used one. Most shops have lots of spares out back. You can install it there and test for spark. If it works you can pay them, if it doesn’t you know that is not your current issue. At least that’s a free way to test the validity of your current coil and you’ll get a good used one if yours isn’t working.

 

[MartDalb]

It’s far from ideal in picture 2. The end of the HT wire should have the strands exposed and wrapping around the spring. That spring should be pushed right back too.

Either way this seems not to be your issue.

Don’t be too disheartened, this is all part of the “fun” of fixing saws or any engine. You have a good group of guys on the forum behind you.

My suggestion is to do a quick search for used ignition coils (OEM) and give it a go. You may be able to call your local Stihl shop and ask if they have an good used one. Most shops have lots of spares out back. You can install it there and test for spark. If it works you can pay them, if it doesn’t you know that is not your current issue. At least that’s a free way to test the validity of your current coil and you’ll get a good used one if yours isn’t working.

It’s far from ideal in picture 2. The end of the HT wire should have the strands exposed and wrapping around the spring. That spring should be pushed right back too.

Either way this seems not to be your issue.

Don’t be too disheartened, this is all part of the “fun” of fixing saws or any engine. You have a good group of guys on the forum behind you.

My suggestion is to do a quick search for used ignition coils (OEM) and give it a go. You may be able to call your local Stihl shop and ask if they have an good used one. Most shops have lots of spares out back. You can install it there and test for spark. If it works you can pay them, if it doesn’t you know that is not your current issue. At least that’s a free way to test the validity of your current coil and you’ll get a good used one if yours isn’t working.

Yeah i did weap the wire as you mention here.
Do you know how the other end should look like?
I took it out and it was just a tiny hole into the wire that sits on a small needle. Does it need more exposed wire in that end as well?

And yes, this forum, and all its amazing folks have helped me so many times on various saws.

I might be able to call some shops, but I have had very little luck with stihl shops and used items, seems to be vastly different from US to EU on that side of things?

Anyhow, ill report back in. And try to check the other wire end. Perhaps remove the kill switch entirely and try that.

 

[Vintage Engine Repairs]

That little hole in the HT lead is because it is threaded onto a screw in the ignition coil which in turn gets covered by a rubber boot. It should screw on tight. Confirm that the screw in the ignition module is clean and free of rust

 

[MartDalb]

That little hole in the HT lead is because it is threaded onto a screw in the ignition coil which in turn gets covered by a rubber boot. It should screw on tight. Confirm that the screw in the ignition module is clean and free of rust

Roger.

I removed a little form the wire end before reinstalling it - no spark.
I also removed kill switch + red wire that leads to carburator - no spark

@SteveSr - You mentioned continuity on the carb wire, can you perhaps explain a way to test this?
I tried to touch the "red wire" end and other end to metal - it showed it had continuity. But can I even test it like that?

 

[Vintage Engine Repairs]

I’d suggest the next port of call is buying a used OEM ignition coil that you can verify works and see if this changes things.

 

[drf255]

Update.
Put the saw back together to test it out.

No start, No spark.
Tried New spark plug, brand New.
No spark.

Reset the distance on ignition module.
No spark.

Sigh...

Did it run when you got it?

If it did, doubt the coil went during repair. Did you put some mix down the carb bore and see if it popped?

How friendly are you with the dealer? Pretty sure those ignition parts are lifetime guaranteed for the original owner only by Stihl.

 

[MartDalb]

Did it run when you got it?

If it did, doubt the coil went during repair. Did you put some mix down the carb bore and see if it popped?

How friendly are you with the dealer? Pretty sure those ignition parts are lifetime guaranteed for the original owner only by Stihl.

No no it's all on me, I bought it knowing it would not start - just did not expect it to be this sorta thing.
Had it been any other regular non Mtronic I could have just slapped on a spare coil....

I could go ask my local Stihl, doubt they will help though.
Another solution is to buy an OEM (stupid expensive and twice the price I paid for the saw ), test it out and return it if It doesn't help.


Open to any suggestions!