A little help with carb tuning

[stihl025]

I have had my Stihl 025 for 10 years now and still running strong. Finally decided to do the muffler mod, what a difference that makes...

Recently, I took my saw to my local dealer to have it re-tuned after the mod. Got it back and having some trouble with keeping it running. It is a little slower to accelerate now, and if I let off the throttle, it will die when returning back to idle. The first thing that I suspected was that I opened the muffler too much that now it doesn't have enough back pressure. But after reviewing the muffler mods posted on this site and comparing them to what I did, I don't believe that to be the case. If anything, I was a little conservative in opening up the muffler.

I have adjusted the idle srew in a little to help, but just doesn't seem to be enough to keep the saw running at idle without the chain starting to turn. I am not sure if I should return back to the factory specs and try that or not. If I do that, I am worried that I may run too lean.

If anyone can offer some suggestions for some carb setting to try, it would be greatly appreciated.

 

[Lakeside53]

Hmmm... I'd take to back to the dealer.... If he gave it back to you like that, someone made a mistake.

Take it back on both L+H to 1 turn out from gently seated. Muffler mod or not, it will work just fine IF everything else is correct. You may need to make a small adjustment on the L to make it idle correctly when warm. 1 turn out on H is richer then you need, so don't worry about being too lean.

If the saw does the same thing, then you likely have an impulse line problem.

If it runs fine, make very small adjustments to the H screw leaner while listening for the "4-stroking" sound. If you're worried, just leave it at 1 turn

http://www.madsens1.com/sub8.htm Then select "saw tunning" fore a good tutorial.

 

[MacDaddy]

The low side it out try turning it in a 1/8 and if it gets better do it again untill its the best you can get or go out with it the same way and you will figure it out Its easy after you do it a few times

 

[Patrick62]

Adjust the low for the best speed, then run it just a tiny bit richer than that. Set the idle to what you like. Next go find a test log an keep playing with the hign (appox 1 turn) until it runs nicely.

Idle flows so little that the stock muffler would not restrict it, your gains are at speed where the mod allows better flow.

-Pat