MS 150 muffler mod tuning

[MiloFrance]

Greetings from France O knowledgeable ones. not been on the site for a while as everything was running smoothly with my jonsered and little Alpina. Things have moved on in the last couple of weeks as a tree surgeon friend was selling his 2-year old well used but looked after saws (3 of them!). As the title says one of these is an MS 150. I have just done a small muffler mod to it that has made a huge difference. Not only does it sound bigger but it runs better and you could almost say it's a much happier saw. As there was so much carbon around the muffler I thought I should give it a bit of a tune. idle speed is absolutely fine but the weird thing is that it's so happy that turning the screws for low and high doesn't make very much difference. It revs like mad, idles happily, does not bog down and cuts like it was new. The only thing I noticed against a shaft or sunlight was some smoke.
So my question is is do I need to to take something out that limits the range of the screws, or just get it to happiest and keep an eye on the the carbon build up?
Hoping you are all safe and well...
Milo

 

[rupedoggy]

The tree surgeon used a heavy mix on his oil. That is why his saws lasted a long as they did in commercial service.

 

[MiloFrance]

Thanks Rupedoggy. He uses the same mix as I do. I suppose what I'm getting out is how can I tell if I'm running too lean and therefore at risk of over heating from being too lean a mixture, burning out or or other things I know nothing about?

 

[Mad Professor]

Greetings from France O knowledgeable ones. not been on the site for a while as everything was running smoothly with my jonsered and little Alpina. Things have moved on in the last couple of weeks as a tree surgeon friend was selling his 2-year old well used but looked after saws (3 of them!). As the title says one of these is an MS 150. I have just done a small muffler mod to it that has made a huge difference. Not only does it sound bigger but it runs better and you could almost say it's a much happier saw. As there was so much carbon around the muffler I thought I should give it a bit of a tune. idle speed is absolutely fine but the weird thing is that it's so happy that turning the screws for low and high doesn't make very much difference. It revs like mad, idles happily, does not bog down and cuts like it was new. The only thing I noticed against a shaft or sunlight was some smoke.
So my question is is do I need to to take something out that limits the range of the screws, or just get it to happiest and keep an eye on the the carbon build up?
Hoping you are all safe and well...
Milo

not framiliar with that saw. Does carb have both Hi/Lo screws? If so check for limiter caps on the screws

 

[lone wolf]

not framiliar with that saw. Does carb have both Hi/Lo screws? If so check for limiter caps on the screws

Mine has a limiter on the H it needs to be removed by drilling a pin out of the side then a screw into the limiter and pull it out. Also he needs a special tool from Stihl to turn the H.

 

[rupedoggy]

. It revs like mad, idles happily, does not bog down and cuts like it was new

Well???????????

 

[MiloFrance]

I suppose what I'm getting out is how can I tell if I'm running too lean and therefore at risk of over heating from being too lean a mixture, burning out or or other things I know nothing about?

This... Don't want to blow it up after having it a week!