New CY50T3, Should I adjust carb 1st? All advice welcome.  By  upgrayedd (Read 539 times)

Most likely your carb will be sealed, which means that the air/fuel mixture screw is covered, and usually the float bowl screw heads are cut off. You can unseal it, or buy an after market carb like a Keihin (one of the best).

Once you have your carb unsealed or replaced with an after market one, you'll need to adjust the air/fuel mixture. Start by turning the a/f screw all the way in, but be sure to count exactly how many 1/4 turns it takes (in case you need to start over). You want to adjust the a/f screw 1/4 turn at a time until you have the highest idle rpms you can achieve. Once that is set, adjust your throttle's idle screw till your rear wheel stops turning. NOTE- all of the adjustments should be made slowly, turn the screw 1/4 turn then wait a full minute for it to level out at the new settings.

Once you have your idle speed set, it's time to go on a WOT ride for a few miles, then pull your spark plug and check the ceramic's color around the electrode. You want a nice coffee color, white or barely grey means you are too lean, which is not good. If you have a black plug or a bunch of deposits on it, you are too rich (not as bad, but still should be adjusted). Too lean can cause your engine to overheat, which can cause many different issues (burnt/melted valves, cracked/melted piston, etc etc).

You will also want to check all the screws, nuts, and bolts to be sure they are all tight, perhaps add a drop of lock-tite to anything you won't be removing more than once a year. Then check all the wiring connectors, and if any seem loose, add a drop of silicon to keep them snug.

Have fun with your new ride!