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 Carb issues

 Created by: monty341
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 Posted: Jul 16, 2022 12:55PM
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Member since:Jul 18, 2019
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thanks for your time and info! much appreciated!

 Posted: Jul 16, 2022 10:50AM
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Member since:Aug 14, 2002
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CA
There are no exact "settings". Assuming you are starting from scratch:
The idle screw should be turned in until it just starts to touch the throttle lever, then add about 3 turns so the throttle is open slightly. You will fine tune it later.
Next, find the fast idle adjustment screw. Pull/rotate the choke lever until the mark on it is in line with the screw and turn the screw in until it just touches at the mark.
Now go to the main jet nut. Push the choke all the way in to fully release its mechanism. Loosen the jet lock nut. Turn the main nut so the tip of the jet is flush with the bridge inside the carb throat - you will have to remove the dashpot to see down. Once the jet is flush, reinstall the dashpot, making sure the needle slides very smoothly into the jet. To do this, undo the dashpot damper cap and remove the damper piston. Now lift the dashpot core and let it drop - it should land with a definite tiny clunk. If not, and you have a fixed (non-spring-loaded) needle, you may need to re-centre the jet. Now turn the main jet nut to lower the jet about 1/8" (3mm). Close the dashpot damper cap.

You should be able to start the engine with these settings, though it won't be tuned. Note, on a HS4, that the choke mechanism actually pulls the main jet down to richen the mixture and opens the throttle to increase the idle speed. You may find it useful to apply some choke to start it and then gradually release the choke as the engine warms up. Once it is warm and you have fully released the choke, you can adjust the idle screw to get a slightly fast idle (say 1200rpm) and then proceed to adjust the jet to optimize the idle mixture by turning it in and then out until the idle begins to drop in each direction, then set it in between. Count the nut flats as you do so. It might be 3 or 4 flats each way. Bring the lock nut up into position, but don't lock it yet.

Reduce the idle speed to 800 to 1000 rpm and adjust the mixture again. Once you are happy, snug up the lock nut.

Test drive!


.

"Hang on a minute lads....I've got a great idea."

 Posted: Jul 15, 2022 08:28AM
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Member since:Jul 18, 2019
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hello all,

Could someone please tell me the "Settings" on a single HS4 carb? like the numer of turns on the jet neddle nut and idle screw adj?
thanks!