2-cycle carb adjustment

Discussion in 'Mechanic and Repair' started by Craig Turf Management, Jul 29, 2001.

  1. Craig Turf Management

    Craig Turf Management LawnSite Senior Member
    Messages: 354

    Can someone with more mechanical inclination than myself, explain to me how to adjust the carb screws on 2-cycle stuff. I need to adjust these from time to time, and running the equipment to the shop for something I know I can do myself is killing me. What I need to know, is how many turns etc. to get the things running, and then hoe to fine tune it.
    All of my 2-cycle equipment is ECHO Commercial.
    Preciate it, Bill Craig
    P.S. Assume that I have already changed the plug and filters, dumped the old gas etc.
    Thanks, Bill:confused:
  2. vipermanz

    vipermanz LawnSite Bronze Member
    Messages: 1,773

    turning the screw IN will give it more air, less fuel,
    turning the screw OUT will give it more fuel, less air,

    Turn the screw all the way IN Until it gets ALMOST all the way tight, DO NOT OVERTIGHTEN!,
    unscrew it 1 1/2 turns, crank the engine (if not possible forget about everything else i say), once engine is running , adjust the screw OUT for MORE power, IN for LESS power,

    There are others that can give you a more precise answer, but mine was off the top of my head,

    Hope this helps!
  3. lakeviewnw

    lakeviewnw LawnSite Member
    Messages: 27

    Most manufacturers, and your dealer will strongly suggest you have it set at "factory settings" and leave it alone, to get the best performance out of your equipment
  4. sdwally

    sdwally LawnSite Senior Member
    Messages: 386

    On 2 cycle equipment be very careful on adjusting the screws. Factory settings should be maintained, problem is might require carb kit. Big mistake most people make is adjusting the high idle screw to lean and burning the piston and cylinders, especially on chainsaws. Most 2 cycle high idle screws are set by engine rpms, and rpms vary from machine to machine.
  5. SMB

    SMB LawnSite Senior Member
    Messages: 323

    Clean your muffler and take out the spark arrestor screen, you'll be amazed at the power increase!
  6. John DiMartino

    John DiMartino LawnSite Silver Member
    Messages: 2,555

    We always adjust ours with the engine hot,and with a clean/new air filter.we adjust it wide open,no load,back it out until it revs clean to top Rpm's,then turn it in a hair ,so it blubbers just a tad at peak RPm's.We then try it under a load,if power is good,we leave it.We have a hand held Tach to set RPM's with,we use it on chainsaws mostly.If you leave it adjusted for peak RPM's,it is usually lean,and mean,and will blow up,if abused,or run real hard,and slightly under oiled.
  7. Craig Turf Management

    Craig Turf Management LawnSite Senior Member
    Messages: 354

    Thanks to all of you mowchanix out there. I very rarely have a problem with the 2-cycle equipment, but it's a pain in the butt to take it to the shop for such an easy fix.
    Just how do you go about cleaning a muffler anyway?

    Thanks for your help, Bill Craig:blob4:
  8. horace315

    horace315 LawnSite Member
    Messages: 2

    some two cycle engines have limiter caps on the adjusting screws,that is factory settings.if you have overhauled the carburetor or removed the screws look on the carburetor casing there should be two letters one with an h/high one with a/l low.low is your idle high is full rpm's.i will explain this as if both screws were removed.start with the low end screw,screw it out 2 1/2 turns,then the high end screw turn it out 3 turns.that should get you started.attempt to start the unit with the manufacturers suggestions choke pull start 5 turns then half choke,the engine should start but run rough burble sounding that is a rich setting.adjust the high end screw until you hear the engine run to its peak rpm then back out on that screw 1/4 to 1/2 turn,next set the throttle for idle and adjust the low end screw out or in until you get peak rpm at idle back out on this screw 1/4 turn.open throttle to high again and adjust the high end until it peaks again then back out on the throttle 1/4 to 1/2 turn.you always want a 2 cycle engine to run rich for two reasons the extra fuel heps cool the engine and also it gives you a little more lubrication.after you are satisfied with the settings install the limiter caps back on,most have a white for idle brown for high end.

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