HELP! HT131 running issue

[Paul Lloyd-Jones]

I have a Stihl HT131 pole saw that had a broken choke switch that could not be repaired apart from replacing the carburetor. So, I replaced the carburetor today. (I also did a valve adjustment.)
I have very limited experience with tuning carburetors. I played with it a bit, and was getting it honed in pretty well, I thought. But then, after making a few cuts with it, it started faltering/undulating as I would hold the throttle, even when I was not cutting. I don’t know if those are the right words to use to describe it, so maybe someone can help me out. Also, I have a short video of it, but I’m thinking there is no way to post videos on this website?
Anyway, does that seem like something that would be related to the carb tune?
Just a note: I also accidentally pulled out the spark plug boot spring(?), and had to reinstall it in the boot.
Thoughts?

 

[Lone Wolf]

I have a Stihl HT131 pole saw that had a broken choke switch that could not be repaired apart from replacing the carburetor. So, I replaced the carburetor today. (I also did a valve adjustment.)
I have very limited experience with tuning carburetors. I played with it a bit, and was getting it honed in pretty well, I thought. But then, after making a few cuts with it, it started faltering/undulating as I would hold the throttle, even when I was not cutting. I don’t know if those are the right words to use to describe it, so maybe someone can help me out. Also, I have a short video of it, but I’m thinking there is no way to post videos on this website?
Anyway, does that seem like something that would be related to the carb tune?
Just a note: I also accidentally pulled out the spark plug boot spring(?), and had to reinstall it in the boot.
Thoughts?

New OEM carb or what ? If so, you shouldn't have to tune it, something else is wrong, the video would help. What did you gap the valves at ? Is the spring on the coil wire installed with the spike end into the coil wire properly? I wonder about the coil being bad, did you replace the plug yet?

 

[stihl #1]

Look under the carb and there is a black hose that comes from the crankcase and fits over a brass tube on the bottom of the carb.

Note the top carb in this pic which is the carb you have. This tube supplies an impulse signal to drive the fuel pump, and is much larger than what is found on a two-stroke. It is easy to get this out of place when installing a carb on the 4-MIX engines, so it might be kinked or slipped out of place after you ran it some. Just something that is easy to check and might be the problem.