Small Engines (Lawn Mowers, etc.): STIHL HS85 Poor Running, zama carburetors, air mixture

Question
Hello Mr Bridgers;

My Father bought a New STIHL HS85 hedge trimmer in Dec 2001, it has never run smoothly and is particularly bad in warm conditions, when it stops it is almost impossible to re-start. Customer Service at Stihl is um 'Poor', My father was an engineer by trade but has not been able to cure the problem, it has been to several service companies but they appear to know less then him.
Please advise as best you can, many thanks....

Regards James

Answer
Hello James:

First, Remove the Muffler and make Sure the Exhaust Port and Muffler are Clear of Carbon. Stihl has a Very, Very Touchy Carburetor. If the Air Mixture Screws are Not Set Correctly, you will have Problems Starting the Engine. I have Also Found that Some of these Units came from the OEM with the Carburetor Metering Needle Set Improperly. That is Most Likely the Reason for the Hard Starting when it was New. To Properly Assist you, I Require the OEM (Walbro, Zama, ect) and the Model Numbers Off the Carburetor. With these I can Locate a Breakdown of the Carburetor and Better Assist you. You can Get Technical Information on Zama Carburetors at this Site Addy; http://www.zamacarb.com/tips.html and Select the Technical Guide. This Guide Works Well for Walbro and Other Trimmer and Chainsaw Carburetors. If you Hit a Snag or this Does Not Correct the Problem, I am Here if You Require More Assistance. Hope this Helps. Let me Know What Happens, Please. May the All Mighty Bless You and Yours. Thanks.

Good Luck

Respectfully

John

PS: I am Allowed to Answer 10 Questions a Day. If you See I am Maxxed Out, then Try Submitting your Question at or Just After 8pm EST (US). My New Day Starts then. Comments and Ratings are Greatly Appreciated. Thanks.

Respectfully

John