John deere buck 650 ext want start but when u turn on the key it lights up

The engine in a 2004 JD Buck should be a Rotax 650, which is a 2 cylinder 4 stroke water cooled engine generating 62 hp. With that said, the most likely cause of oil in the air filter and leakage from the top of the motor is excess pressure in the crankcase. A cracked block is a possibility, but the most likely culprit is worn piston rings. A compression test should help narrow it down, but in either case you are looking at a complete tear-down of the engine.
https://www.rotax.com/en/products/rotax-powertrains/details/rotax-650.html

Back firing is usually a lean fuel mixture caused by partially blocked jets or badly adjusted idle screw

dud just get a ford. trail buckc?

Replace the starter, the overriding clutch is defective in the starter.

use wd40

bad battery if it wont over, if it will turn and over and not start then you have a bad gas issue with a gummed up carb if its the carburatored model...

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john deere trail buck 2005 650 when accelerating before it gets to top starts cutting out pretty bad. In the high altitude it was doing that and not it does it here in MO. What causes this a weak fuel pump? Thank

New Brake Line or Assy

You post your question under ATV's
Then you buy a service manual or ask
about one at a dealer

requires and specific puller. Easier to remove secondary clutch if you are trying to replace the belt.