Starter works, won't crank engine.

[huntergrundman]

Hello,

So I recently purchased a used TaoTao 50cc scooter with a GY6 engine. The electric starter switch wasn't working at all when I purchased it, but the scooter would kick start. I have recently replaced the starter as well as the solenoid and fully charged the battery. When I try to use the electric start switch now I just get a "Whirring" sound and the starter is not engaging the engine. Any advice towards fixing this issues would be greatly appreciated!

[FrankenMech]

Check under the CVT cover and see if the starter Bendix mechanism is engaging the Variator sprocket.

You will need a support for the end of the starter. You can find one on this site.

[GrumpyUnk]

The whir is as Frank said, the Bendix drive failing. When the starter motor is switched on by the starter relay, the armature spins up REAL quickly. That acceleration should leave the Bendix standing still, not rotating, which causes it to ride up an internal ramp, which pushes the gear out to engage the gear teeth on the crankshaft.
If the starter motor is failing, or binding a bit(dirty sticky bearings?), it will not accelerate as quickly, and the Bendix will not ride up its ramp, etc. If the cables are not conducting sufficient power, or the battery is lacking, or the relay internal contacts worn, the same thing can also happen, due to low amperage.
You can remove the CVT cover, wiggle the Bendix out from behind the gear teeth, clean the ends of the Bendix, and clean the bushings, and apply a dab of grease to each. Put it back together, and it may work. You may also be able to clean the Bendix if it is sticky, and not willing to move freely on its ramp. If the Bendix seems clean and free to move, then the battery, cables and relay are still possibles, as it the starter motor bushings and brushes.
If you happen to have a spare of any parts, substitution can eliminate them from the array of possible causes.
tom

[huntergrundman]

Thanks to everyone who replied. It ended up being the battery after all. I replaced the solenoid, starter, and Bendix for good measure though. Cheers.