tecumseh carb settings which screw is which

[793bob]

i would like to know how to adjust the screws on a jiffy 2hp engine which screw is the low idle and high .how to adjust each.

thanks

[Knotwood]

The low speed circuit is ALWAYS the screw closest to the engine, it feeds fuel to a spot at or just behind the throttle plate, whereas the high speed circuit is further "upstream". This goes for chainsaws, lawnmowers, and snowblowers, no matter who made the engine.

[Knotwood]

Settings are usually about a turn out (from a lightly seated position) for each, but can vary due to governor spring tension, temperature, and load conditions. You may need to lean the high speed to 3/4 (or even 1/2) depending on where it runs the best. The low can vary a bit, too, richening up the low speed will affect how the engine picks up on acceleration, and if it stays in the powerband (or governor range) or stumbles when it needs a little gas to bring the engine back into the "zone". I usually try to get the unit started, let it warm up good, then try under a moderate load, if if bogs under load, slightly richen the high speed first. Do that first. It should keep running and accelerate clean from idle to high speed, use the low speed to change the idle if it doesn't respond, then repeat the high speed load, adjust it so when a heavier load is applied, the engine starts to run "clean", which means the sound levels off, not blurting out- they call it "four-stroking" when it runs a little rough. It will "four-stroke" with little or no load, then run clean with a moderate load. Test the low speed again, any changes should be minimal, about 1/8 turn or less any time you adjust the carb. It will take some experimenting if you are new to this. Remember to always use fresh fuel and a good oil mix.