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Old 07-31-2019, 09:28 AM   #6
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I am: Cliff S
Join Date: Feb 2007
Location: Belleville Ont.
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Re: Carburetor setup

First; The low speed needle usually has no effect on high speed mixture! (explained in adjustment)
1. attach a clean piece of fuel line to to the fuel inlet.
2. close the throttle barrel on a "T" pin or something the same size.
3. Blow in the fuel line and adjust the low speed needle so a small bit of air jus starts to come through.
4. Open the throttle full and look down the barrel. Check to see if "the low speed needle" is clear of the end of the spray bar, on most engines it will be.
5. Remove the "T" pin. Open the throttle full and blow in the fuel line and adjust the high speed needle so I restricts about one third of the air flow.

You will find that the low speed needle is quite close and the high speed is quite rich.

6. Start the engine and set the high speed needle.
7. Completely peak the engine at full throttle. then richen it so it looses 200 - 400 RPM.
8. Now try the idle, what we are looking for is 2500 - 2600 RPM.
9. Adjust the low speed needle for maximum RPM then richen it up 1/8th of a turn. You might have to blip the throttle to clear the excess fuel in the base. If your RPM is not at a good RPM for that engine, adjust the idle stop screw and readjust low speed needle to get a reliable idle.
10. Every now and then give the engine a good burst of full throttle to clean out and heat up the engine. When you go back to idle it will probably go to around 2800 - 3000RPM, then it will loose several hundred RPM because of the slightly rich mixture which builds up a rich mixture in the lower crankcase which the engine uses to accelerate when you open the throttle.

"If my being here has made your day a little more pleasant then I have done my job" Red Skelton 1913 - 1997 (famous Comedian)
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