Stihl 420 Blower Carb Adjustment

Discussion in 'Mechanic and Repair' started by sd_stack, Nov 12, 2005.

  1. sd_stack

    sd_stack LawnSite Member
    Posts: 3

    I left my brother-in-law borrow my blower and he wasn't smart enough to start it. He decided to mess with the adjustment screws on the back and I can't get it back like it was. :realmad: It was perfect before he messed with it. He said that he only messed with the big screw on the right. Can anyone tell me how many "turns out" from bottom that the screw normally is from factory, or even from a working unit for that matter. Thanks for the help.

    Homeowner Steve.
     
  2. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    What do you mean "like it was"? Many of us get caught by the screen getting clogged in muffler. I am not sure that one adjustment screw has much affect on running. But start by turning it in fully than back it out 1 1/2 turn and try running the unit. Keep backing it out as needed. This unit is very easy to flood when hot so maybe it still has a lot of fuel in filter or on spark plug.
     
  3. sd_stack

    sd_stack LawnSite Member
    Posts: 3

    "Like it was" - the unit is brand new and has been operated a dozen times for a total run time of about two hours. The screen shouldn't be clogged but I haven't checked that.

    One screw shouldn't have that much affect on one but it ran fine when I gave it to him and he turned the screw and I can't get it to run. The unit if flooding, but not while hot. I doesn't get a chance to get hot. I pull on it 10-15 times and take the spark plug out each time to find it flooded. I clean the plug and try again. I do this until I am tired.

    I will try the 1-1/2 turns tomorrow and let you know how that goes.

    Thanks for helping out a lowly homeowner that bought above his head... it sure does a good job though... when its running! :p
     
  4. ed2hess

    ed2hess LawnSite Fanatic
    Posts: 13,329

    The starting procedure for that unit cold is put it on choke until it fires once. Then take it off choke and pull it until it starts. Wet plug might indicate that the screw is out too far. Could be needle valve stuck, but since you know he turned that screw turn it in cw.
     
  5. sd_stack

    sd_stack LawnSite Member
    Posts: 3

    Thank you very much ed2hess. I turned the screw all the way in and backed it out like you said it it fired right up.

    Thank you so much for the help.

    Steven
     

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