Chainsaw Repair

I have a Husquavarna 257 with a Welbro HDA-144-1 carb in it. I am attaching a screenshot of my repair guide that shows the exploded view of my carb. I have an arrow pointing to a screw that I would like to know what this screw is for and what does it do. I am trying to get my saw to run and I know it is not the L or the H but does this screw need to be adjusted or what. Thanks

That screw is for you idle adjustment. To start I would screw it in till it stops and then back out 2.5 turns as a starting point. It allows a small amount of fuel air mix into the motor at idle. Would also add that you're H and L screws should be 1 turn out from a lightly seated position. Hope this helps.

Yes the spring will compress as you turn it in. Trim off the little plastic tabs of of the black and white limiter caps. You can use a razor knife or razor blade. Just watch your fingers.

OK, it's dark and I turned on my porch light where the saw is sitting and you know those LCD bulbs that they say last 20 years or better. Well that one didn't cause I replaced it at Thanksgiving. So I aimed the best I could and took several. Here is the best one. I circled the H-L screws in black. Then I did a dotted line where I think you said to cut the limiter cap on the white one because that is the only one that is showing good. Is that correct?

Now last year about this time of the year I replaced the carb unit thanks to a youtube video and someone here helping me by answering questions. I ran it all summer although I did take it to Ace hardware to get them adjust the carb for me. I have never been any good at adjusting those things. Anyways it ran all summer but toward the end of the summer it got to being hard to crank. Taking a dozen pulls. Then it got to where when it did crank I could run one full tank of gas but it I turned it off or if I had to refill it with gas that I just couldn't get it started back up for anything. Almost like it needed to cool down. Cause if I left it or came back the next day it would after another dozen pulls crank back up and then not after it got hot. So I broke it back out this week to check it out before the weather really gets nice.

I had no idea you could cut those off.

Found this on the HDA carb
http://www.walbro.com/media/21886/HDAseries.pdf