"Racing" over-reving 028

[logbutcher]

Help! My over-abused 1984 Stihl 028AV has a tendancy to over rev and race. Chain-braking stops it until after a cut. The other time, years ago, when it did this, the repair guru fixed an air leak to the carb.
It races when warm and only after WOT cutting. I've tried adjusting the hi and lo screws.
Under full disclosure: I drilled 2  small  3/16" holes on the exhaust under the screen. Got to blame those who recommended it here !
Any ideas out there ?
BTW: I'm looking at the MS260, MS250, 346XP for a soon replacement. Advice ?
Can't take responsibility you know.

[Ed_K]

 I'm planning on the 346 xp for my next small saw  .

[Minnesota_boy]

Check for a partially plugged fuel filter.  It might be outrunning its supply of fuel and thus running a little lean.  Could need a diaphram in the carb too.

Other things to make  a saw race would be crankshaft seals or a vent line or fuel line with a crack, or a gasket leak between the carb and crankcase.  It could even be caused by a worn throttle shaft in the carb that hangs up a bit on return to idle.

[Oregon_Rob]

If it were me, I would rebuild or have someone rebuild the carb, replace the fuel lines and adjust the carb. What you are describing is for sure, too much air/too little fuel thing and not a good way to run a saw, unless you want bigger problems

[tony_marks]

  well when u put the holes in u needed to readjust the carb..
   although i never got that reaction from opening one up..
 logbutcher i got say any advice u take on these forums,,iis
 given as an effort to help.. its your responcibility to use your on judgement ,,and its your responcibility if this type thing happens..
no offense intended but if these experienced mechanics and users ,,are willing to share thier knowledge ,,we should take
what everhappens from our actions,, in stride..
 i use to hear fellas talkin how theiier saw just screamed..
 after blowing 2 up .. i thot better of it.. now they only scream in cut...mabe u should take it to the fello that fixed it last time.. sounds like the same problem.. also i think u can cap off the holes u drilled .. if that fixes it problem solved.. good luck..

[logbutcher]

Thanx for the super advice. I can do the filters, lines, throttle shaft checks, but will leave a carb rebuild and crankshaft seal check to the local Stihl guy...he's good.
"Taking responsibility" and blaming : sorry Tony M, it's just an old Army joke for those who blame everyone else for screwups. Kidding here.  :Got to be PC I guess. Whew, I will be careful next time.

[tony_marks]

  just overlook me.. u guys familar with each other,,im dont know someof u....so i missed u meaning.. it aint the first time and sadly wont be the last..  i use to box a little.. mite o got hit a few to many times..