20 Most Recent Oregon Scientific Complete Carburetor for Stihl 4122 Brush Cutter and 4226HS Hedge Trimmer - Page 2 Questions & Answers

high 2 turns out and low 1 and 1/2 turns out
after you get runing up operrating temp ajust
again throttle wide open ajust high neadle and
win idle ajust low neadle

look at your local lawn and garden place some times they have extra parts that you can use for your trimmer. Or call the company them selfs and ask them if they have parts.

call the company that you bought it from or the manufactor might have it yet so they can send it to you.

You can look on the internet, some times these things are on there or you can call the company and see if they will send you other book for it.

Clean the carb and give new gas.

should be a zama cafb...look on the main body of the carb...then the other side...go to this sitehttp://www.zamacarb.com/prod_lookup.cfmscroll down to product look up by type...this will be 3 alpha-numeric for instance C1Q (see photo marked first)...so click on that square and take the other side top alpha-numeric (see photo marked second) and will see select model...scroll down till you find yours, click search and it will take to to a break down...

remove the muffler and run it if runs good open the muffler and clean the screen

take off the muffler and try it if ok with the muffler off open the muffler and clean the carbon from the screen

this worked for me just nowhttp://www.stihldealer.net/videolibrary/OnePlayer.aspx?v=27&vt=27&vb=2&id=27

A shop like www.arcolawn.com can get you Stihl tools and parts.
It sounds like your carburetor is not meetering the fuel properly. A rebuild may work but the carburetors on many machines have fropped in half in the past 2 years.

You may have a bad seal on the crank shaft or an air leak somewhere. If you take it to a dealer most shops charge less than an hour time to perform a full check on the machine and you can do the work.

Good luck

The "H" is the adjustment for the higher rpm range
The "L" adjusts the acceleration and low rpm
The last is the Idle screw

I would check the spark arrestor screen in the muffler. They are known for plugging up and causing serious running problems.