Had to remove motor to repair motor mounts on a redcat 110. Now the motor is back in but the motor won't crank properly. Has plenty of battery power but it acts like it does not. With spark plug removed, it cranks fine but won't when the plug is in. Acts like it cant get past the compression ( will do compression test next). Everything internal spins fine, starter seems to work fine but idk how fast it's supposed to turn. The atv was doing this before the motor was removed and I was tasked with trying to get it to run again. Brand new battery, new fuel, carb cleaned well. Will somebody please help!

 

have you pulled the starter out? have you tested it "on the ground"? i know you said the battery has plenty of power, i presume you've load checked the battery? i'd start with checking the starter to see if it is sluggish and pulling a lot of juice out of the battery.

 

Everything Jaster94 said is correct.

Here are some more ideas to try. More tests give more info to chew on:

1) Try Jumping your quad battery to your car or truck. Be extra careful to get the polarity correct. Does the quad crank normally? If so the battery is bad or discharged.

2) Use a meter to measure the battery voltage right on the battery terminals while cranking the quad starter. What do you measure? It should not be below 11.8 volts.

3) Measure the voltage at the starter motor while cranking the starter. Red lead goes onto the starter motor, black lead goes onto the starter motor case. What do you measure? If you have low voltage here then you've got a bad connection somewhere between the battery and the starter motor (through the starter solenoid) or a bad ground return.

Since you've had the engine out, a bad ground return is really suspect. Follow the big fat heavy gauge wire from the negative battery terminal. It should go down to the engine and be securely bolted to the engine case near the starter motor.