What is wrong when full power on throttle but only clicks

Thoughts -
No/poor connection between power source and motor
Motor failure
Only someone with their hands on the bike can fully diagnose.

Check the battery voltage right after the charger shuts off. Should be around 13 volts on each one. Short the power switch contacts and if that helps replace it. Check that the motor and wheel turn freely and dont make noise. Check all the contoller connectors. Sometimes they melt and the connection isnt good. You can always connect the batteries directly to the motor and if it goes full speed then you need what razor calls an electrical kit which has a throttle and controller.

I had the same problem and it was my charger that did not work

I have attached a diagnostic sheet to help determine what is wrong.

broken/missing return throttle spring
jammed throttle cable

If adjusting the air valves on the carb doesn't help. you likely need to have the carburater cleaned. The air adjustment needles are located at the base of the carb at the front. Turn them out until you reach high idle, and then in again, about one full turn. If that doesn't help, you'll have to put a carb kit in, and have it cleaned.

I need help! My son mx650 is charged, but won’t run. Put weight on it won’t move but lift rear tire off ground and runs full throttle

You probably need to adjust your carburetor. You can slowly turn the jet closest to the air filter in 1/8 turn increments while at full throttle and check the response. Ear protection is necessary to be able to distinguish the RPMs from the audio pitch of the running engine.

Hey..my name is Keith..try disconnecting the throttle cable and moving the throttle on the carb with your fingers..and if it makes max power..then it has the wrong throttle cable on it..but if there is no change in power..then i would suspect the govener..if this dont help..please write back