Chinese carburetor
adjustment

Chinese Carburetor Adjustment - WYK Type
Initial settings
Main Jet - Most likely it is set too lean -
If you have a carburetor with dual bleed screws please see: WT Carburetor Adjustment
idle speed - engine should idle just below clutch engagement (it will "ding" occasionally)
mixture screw 1 3/4 turns out


low end adjustment
1. perform the Below adjustments after warming up the bike
2. remove the plastic plug covering the main jet needle
3. using a 2.5mm wide flathead screwdriver, turn out the needle until the threads disengage
4. turn the Jet needle clockwise in very slowly with the engine running. the idle speed will increase (lean) until the highest rpm is found. from this point you will want to turn it counterclockwise (rich) about 1 turn
5. adjust the idle speed screw until the clutch dings occasionally.
6. set the mixture/ bleed screw to 1 3/4 turns out.
7. readjust the idle speed screw if necessary.
8. test ride the scooter, paying attention to how it pulls from stop to 10mph or just before the engines power band kicks in. it should pull strongly, if not try adjusting the Main Jet needle out by .5 turn. repeat the test and adjustment until the engine bogs slightly when throttle is applied then turn the needle back in .25 to .5 turns.

high speed adjustment
9. the high speed can be done most safely on the bench with the chain removed
10. start the engine and hold the throttle wide open. turn the side screw in (lean) until the speed peaks and then turn it back out 1/4 turn
11. readjust the idle speed screw if necessary

test ride and repeat any steps until your engine pulls strongly from stop to full speed.


This is one of the best guides we have ever found on youtube for this engine, watch and learn.



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