Over revving at idle or over revving at full throttle ?

 

At full throttle.

 

Maybe the high speed screw has turned from all the vibration and it is now running too lean. Check that, or have it checked.

 

Running too lean on the high speed mixture screw would cause the RPM to drop, not increase. Same thing with running too rich; it causes an RPM drop. When you set fuel/air mixture, you're looking for the highest RPM that you can achieve between the two drop off points: too lean and too rich. The higher RPM means the engine is making the most power because the fuel/air mixture is where it should be.

I suspect the OP's machine needs its throttle cable adjusted.

 

What Ridin' Green said.

 

and what model hedge trimmer?

 

Yeah, which model? My HS45 is a real hand shaker.

 

It's a HS82T. I'll check the High speed screw. My thought is fuel related but the mix has not changed.

 

what fuel are you using and what oil mix?

 

6 ounces 2 stroke oil/2 gals 87 octane. All of my 2 stroke equipment has been running on this mix for years and I have over a dozen Stihl products utilized daily.

 

i'm kinda at a loss at the moment without having my hands on it. if you want to rule out fuel, get a quart (7.99) stihl motomix. dump out the old stuff and put that in there. see if it changes. if you had brought it to me that would be the first thing I did just to rule out fuel issue. stihl products are made to run on higher octane fuel. the new motomix they released this year is 93 octane. plus it has the full syn stihl oil in it. according to your mixture, your low on octane and high on oil content. understand you have been running for years but motors will run different over time on the same fuel as they wear. up to you if you want to try the motomix, i'm just saying that's where I would start if you came and dropped the hedge trimmer off on my counter. let me know what you come up with, more then happy to help anyway I can. good luck.

 

Look, yer issue is not with the gas/oil mix. I too usually replace a customers fuel with my own shop mix, just a good brand of oil and usually mid grade gas. No hi-test.
More than likely ya gots carb problems. Sometimes dirt will migrate into the HS passages causing a lean condition, resulting in high revs. Try this: while warmed up and revving, slam the choke shut 'till it just about dies, then open choke and let it recover. Do this a few times. Sometimes it helps to clear out the circuits, sometimes not. As others have said, it could just be the HS needle needs tweekin'. Could also be a loose carb/air leak.
Have fun.

 

warming up, slamming, and choking repeatedly. that's just dirty.:dancing:

 

That last sentence is true, and goes along with what I said before.

I know what they do and how to adjust them. Been doing this a long time now. Most of my machines with adjustable carbs on them have 3/4 of a turn stop to stop, not 1/4. Don't take my word for how to do it. read the ops manual that comes with them when they do have adjustable carbs. They clearly tell you how to adjust them, and that tiny increments one way or the other make a difference, and you can hear it and see it on a tach. I stand by what I said in that you can get too lean or too rich before you have gone to the point of power dropping off. Been there, done that.

 

That last sentence is true, and goes along with what I said before.

Only the last sentence ?

I consider mixture adjustments to be quick and easy as long as the carb in in good shape. I think you're making a big deal out of nothing.

 

The engine is equipped with a rev limiter that kicks in at 9300 rpms. Unless it doesn't.
That will cause your over-rev problem. Would it not?

 

Took the trimmer to the shop because they said it was still under warranty. Turned out to be carbon build up in the exhaust. $33.00 and running like new. Thanks for the responses.

 

Turned out to be carbon build up in the exhaust.

Huh ??? Sumpin' ain't right there. Usually carbon buildup in the exh. port prevents it from revving up normally.
That's a new one on me.

 

Let's hope your arteries don't look like that!

 

Don’t know if it idled ok at normal rpm, but my thought was the cable housing had some strain on it-was backed out of one end of it’s mountings, or inner cable not seated fully in the ferrule.

 

'Bama Jeff, what say you ? Come in Jeff...Jeff ?...Jeff...Jeff...Jeff ?

 

I have a stihl HS 82 T that is also over revving @ WOT, and I know for sure is not the exhaust port, because I checked that by the way it's only 5 months old. Take the carburetor off today cleaned everything checked everything it all looks great the only thing I can think of would have to be Rev limiter I'm assuming that's just part of the coil?