Stripped head....helicoil?

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Well, sheeeeet. I have come to learn that the MS462 that I need to fix the spark plug threads on takes an NGK CMR6H plug which is M10x1, I was assuming M14x1.25 like my Echo, Husqvarna and Jonsered saws. That's a big turd in my punch bowl.

Can I still retap it as M14x1.25 and use a comparable plug to the CMR6H or is my only option retapping it with a M10x1 kit?
What other saws do you have? I am trying to figure out thread sizes for bpm7 and 8. Cs 490, 620 and 272xp
 
What other saws do you have? I am trying to figure out thread sizes for bpm7 and 8. Cs 490, 620 and 272xp
I have an echo 590, Husqvarna 445, and a Jonsered 451. All are m14x.125 thread size, I could be wrong but I'm pretty sure that is by far the most common threading of plugs for small engines. Stihl just changed to that smaller m10x1.0 recently I think.
 
I found this useful reverse engineering tool on NGK's site.

Unfortunately there didn't seem to be a full match. I can get the same thread reach (12.7mm vs 9.5mm) and heat range in M14x1.25 but the resistor would be different, 5k vs 10k.

Nkw I'm not sure how big of a concern this, anyone?
Spark plug experts, could I run a 5k resistor plug where Stihl specifies a 10k plug for the 462?
 
I have an echo 590, Husqvarna 445, and a Jonsered 451. All are m14x.125 thread size, I could be wrong but I'm pretty sure that is by far the most common threading of plugs for small engines. Stihl just changed to that smaller m10x1.0 recently I think.
I believe the Husqvarna 500 series pro chainsaws use the M10 x 1 Thread. I know the 545 for sure. I'm not a big fan of the smaller plug, not performance wise. It makes it hard to check compression and it's a bummer trying to look through the spark plug hole to look at the cylinder and piston.
 
That is a real pain, stripped spark-plug threads is got to be one of the worst things to really ruin your day......:eek:)

If I may, here's a talky video on a jury-rig solution I came up with myself that appears to work dandy:


Some background if you're interested:
Another of my hobbies is Johnson Outboards. Anyway, I stripped the threads in my Johnson 6HP I grew up with. Threads were gone, spark plugs just fell out. I noticed that the spark plugs had about say 1/2" of thread, while the hole in the cyl head had about 3/4" of thread. About 1/4"++ of unused hole. Further, I had a set of Champion L78C plugs I don't know where they came from, looked about the same as the original J6C plugs, but with longer 3/4" thread shanks.

SO, I decided, what have I got to lose - I took the pair of L78C's and screwed them right into the head! They went past the stripped area and bit right into the soft-as-butter aluminum that had never been touched, torqued them down and done. They weren't long enough to interfere with the piston, so all good. Looks like your chainsaw head has a bit of extra threads in the hole too.

I did this about 8 years ago. For obvious reasons I haven't attempted to remove the plugs since, and the motor continues to perform flawlessly, starts right up, decent power and speed. See the movie, it doesn't go that fast on my big boat, but on a lighter 12ft jon-boat it flies. The movie was made about 2014, motor still working fine in 2023.....:^)

Hope this helps someone - Cheers!~ Bellarmine
 
That is a real pain, stripped spark-plug threads is got to be one of the worst things to really ruin your day......:eek:)

If I may, here's a talky video on a jury-rig solution I came up with myself that appears to work dandy:


Some background if you're interested:
Another of my hobbies is Johnson Outboards. Anyway, I stripped the threads in my Johnson 6HP I grew up with. Threads were gone, spark plugs just fell out. I noticed that the spark plugs had about say 1/2" of thread, while the hole in the cyl head had about 3/4" of thread. About 1/4"++ of unused hole. Further, I had a set of Champion L78C plugs I don't know where they came from, looked about the same as the original J6C plugs, but with longer 3/4" thread shanks.

SO, I decided, what have I got to lose - I took the pair of L78C's and screwed them right into the head! They went past the stripped area and bit right into the soft-as-butter aluminum that had never been touched, torqued them down and done. They weren't long enough to interfere with the piston, so all good. Looks like your chainsaw head has a bit of extra threads in the hole too.

I did this about 8 years ago. For obvious reasons I haven't attempted to remove the plugs since, and the motor continues to perform flawlessly, starts right up, decent power and speed. See the movie, it doesn't go that fast on my big boat, but on a lighter 12ft jon-boat it flies. The movie was made about 2014, motor still working fine in 2023.....:^)

Hope this helps someone - Cheers!~ Bellarmine

Nice job seems like a super easy way to fix it if it holds up and looks like yours is.
 
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