STIHL 4 mix valve adjustment

Discussion in 'Lawn Mowing' started by WalkerMike98, Dec 4, 2009.

  1. WalkerMike98

    WalkerMike98 LawnSite Member
    Messages: 167

    Thanks to you guys and my local dealer I adjusted the valves on all of my stihl 4 mixs today in about an hour. My local dealer gave me the clearance tool and showed me how to do it. Much easier than I had imagined. Both of my br600 blowers were way out of spec, hard to start and idled bad. Now both run like new. I would suggest to anyone that owns a 4 mix to do this.
  2. mnms0562000

    mnms0562000 LawnSite Member
    Messages: 43

    The recommended time to do a valve 'check' is 135 hours. Glad you got it out of the way.
  3. DFLS

    DFLS LawnSite Senior Member
    Messages: 354

    Guess I have to find a new dealer - the mechanic told me it was complicated, you needed a special tool and if I did it wrong then KABOOM. Where can I get instructions?
  4. grassman177

    grassman177 LawnSite Fanatic
    Messages: 9,795

    we have one 4 mix, it is the extended reach trimmer. it does idle a little too low and dies often. i know they run different anyhow, but this is not used too much. so, i guess i need to look into this huh.
  5. cpt87gn

    cpt87gn LawnSite Member
    Messages: 218

    if you can provide more info that would be great how much did the tool cost i have a
    br550 i want to do it on but i have no clue on how to do it i am mechanically inclined
  6. Stillwater

    Stillwater LawnSite Platinum Member
    Messages: 4,889

  7. WalkerMike98

    WalkerMike98 LawnSite Member
    Messages: 167

    My dealer gave me the tool. Take the shroud off and pull start. Should be no more than 5-8 screws. the valve cover has one screw on top. take it off and rotate by hand until tdc. Then use a 8mm socket and tighten valves until you feel resistance. Should be very little tightening but valves will be way off. They should be at 10 thousands. The stihl tool is pointed and tighten until there is resistance when it is inserted and taken out.
  8. Stillwater

    Stillwater LawnSite Platinum Member
    Messages: 4,889

    you set yours at 10?

    My stihl tech manual says 0.1mm or 0.004 of an inch
  9. WalkerMike98

    WalkerMike98 LawnSite Member
    Messages: 167

    Maybe I meant .1mm. I just used the stihl feeler guage. Sorry for the confusion
  10. Jason Rose

    Jason Rose LawnSite Fanatic
    Messages: 5,858

    When you ask for the gasket for the valve cover make sure they give you the one that also includes the feeler guage. At least the first time... It's a whole $5.00.

    I did mine earlier this fall, first time it's been adjusted in 3 years. It was just getting to where it was harder to pull, but still ran and idled fine. It was pretty far out, considering how tight the tolerance is when adjusted right. I went back and forth between the two at least a half dozen times just to be 100% sure that I had them perfect. Of course you hav to rotate the engine crank to open and close the valves to be adjusted. You can download a PDF with the instructions for valve adjusting, but it's literally just a couple lines long. I was suprised how easy it really was.

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