problem with my 125cc 4 stroke pitbike - Leaking black fluid from exhaust and more

[kboevink1]

my 125cc 4 stroke pitbike Leaking black fluid from the exhaust when it runs, also makes popping noises when reving, and recently there has been a crapload of white smoke shoot out the bake of the exhaust when its running and it dies when running after about 10 minutes

 anybody have a clue what this is thank you, and help is much appreciated 

Edited August 13, 2013 by kboevink1

[markymarkmx]

Check your compression

[erichshonda]

It's burning oil. Sounds like your top end worn. Could also be worn valve stem seals and or valve guides. You need to tear it down for inspection. If your cylinder had grooves in it , it too need replacement due to sucking in dirt. Clean air filter often to avoid this

[T Bolt USA]

Needs Piston kit and valve seals 

or more

The backfire is likely a bad exh seal