Any one here a 4 mix expert?

Discussion in 'Mechanic and Repair' started by txlawnking, Jun 15, 2005.

  1. txlawnking

    txlawnking LawnSite Bronze Member
    Messages: 1,905

    My new employer has LOTS of the 110 4 mix trimmers and edgers.. Today, I was trying to diagnose one that ran like this: VERY difficult to start, when running it would either not rev up like it should, or it would rev instantly to red line at times. It would just not run consistently..
    I thouroughly cleaned the carb, checked for plugged exhaust, and even checked the valve lash, which seemed real loose for this little engine ( probably somewhere around .020" or so).

    Any Ideas? I wondering if maybe a bad crank seal?, or a problem with the reed valve? I was unable to lash the valves, as I don't know the spec, and I was unable to check compression, due to the weird little plug (although it did seem good just cranking it over..
    I'm game to Ideas/ suggestions as this is the first 4 Mix I've ever laid hands on, and probly won't be the last..

    I also tinkered with another that acted like it was missfiring at high Rpm's ( banging out).. Are these things prone to coil failures?

    Almost forgot, the first one is two seasons old, the second is a year old.. Also, bossman said that MAYBE non-mix gas was used ( not certain )?
  2. vipermanz

    vipermanz LawnSite Bronze Member
    Messages: 1,773

    i saw some pretty new units that already had bad coils, i myself don't care for the stihl 4mix line, maybe that's because i had to work on so many..
  3. joe stihl

    joe stihl LawnSite Member
    Messages: 35

    The valve should be .010. The units come with a kit that has a small feeler gauge in it. Get this set and it may solve your problem.

    I don't have much experience with them, but I have seen several with carbon buildup on the exaust valve. Pull the exaust valve and carefully clean the mating surfaces.

    Lastly, the ones built in Germany(serial # starts with 1) seem to have more trouble than the US built ones(serial # starts with 2). Different carbs.
  4. Lawn Masters

    Lawn Masters LawnSite Senior Member
    Messages: 850

    I was told by a mechanic with plenty of experience with 4mix engines, that you could run up to 30 tanks of straight gas through them without damage, not that I recommend it, but it can be done in a pinch.
  5. Grassmechanic

    Grassmechanic LawnSite Silver Member
    Messages: 2,697

    If that is the case, ask him how the crank bearings get lubricated.
  6. txlawnking

    txlawnking LawnSite Bronze Member
    Messages: 1,905

    But my "boss" decided to take them to the dealer.. It was the valve lash on both counts..

    I've also used these things extensivelly now, and I must add, they suck.. the brand new ones we have are still weak..

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