Stihl MS170

[djg james]

I have a Stihl MS170 that I put a new OEM Zama carb on last year. It starts fine and runs but will not idle. I've only used it once or twice since then hence the delay in addressing the issue. I thought it was an easy fix. Run a screwdriver into the screw and open (CW?) it up until it idles. Wasn't sure I was hitting the screw so I removed the cover. I tried to rotate the screw both ways with just hand pressure and it won't budge. I don't want to strip it off and it looks like it's in all the way. Since it doesn't idle at all it needs to be opened up Cw or CCW? Any ideas on how to get the screw unstuck without damaging it?



P.S. I found a video on adjusting it and it does have to be turned CW since it doesn't idle at all. So the question remains on how to free up the stuck screw. Put heat on it (wouldn't think so)? Run it till the engine is warm? Just crank on it hard?

 

[HarleyT]

 

[djg james]

View attachment 910898

Thanks, how many turns was my next question. Any ideas on it being stuck? Maybe it just that I'm not using enough force. Going to slide the carb back past the holes and use a larger screwdriver CW on it.

Edit: Got it! Bigger screwdriver and two turns CW and it's idling now. Thanks. No need to respond further.

 

[Jasent]

What you really need is to swap it out fro a walbro wt215. You’ll have h and L jets plus idle screw. Will have to do a few minor mods to get to the screws ( drill a few holes) buts it’s well worth the trouble!!!!!!!!!! Now it starts easy, idles great, not too rich or lean in the highs.

 

[J D]

You can also replace the fixed jet, the earliest ones were slightly bigger & they got progressively smaller over the years. I have also drilled them larger to achieve the same thing but you need some very fine increment bits to get it right