Motorcycle Repair: Kawasaki FD620D rebuild lacks power, atv owners, gear teeth

Question
We bought a used 2510 Mule here on the farm last fall and have to rebuild it twice now.  First rebuild was due to a spun crank bearing.  Custom cycle shop took care of removing bearing, bathed block and checked tolerances before we rebuilt it. Ran great for a month or two then the plastic teeth on the cam gear sheared off. Replaced water pump and entire cam assbly with one from JD that has a steel gear. Now she sings pretty good (suspect metal to metal cam to crank gears) and we don't have the power we had and it's really putting the gas into the oil.  I'm wondering if we could have bent something when we were trying to start it after the cam gear teeth sheared off. Where do you think we should start looking?  Compression test tell us anything? Some posts I've read about these older Mules indicate they are notorious for putting gas into the oil but everything seemed fine after first rebuild.
Thanks for any direction or experiences you might share.
Larry

Answer
Hi Larry,

The first thing to do is read the spark plugs. Determine if the carburetor air-fuel mixtures are correct.

Check the air cleaner. Clean or replace accordingly.

Check cylinder compression. Follow that with a leak-down test if necessary. If compress ion is within service limits, try tuning the A/F mix to improve performance.

If gasoline is mixed with the oil, I suspect a varnished needle valve (float valve)/carburetor problem.

Visit "www.atvfrontier.com" for more details from other techs and ATV owners.

Respectfully,
Mark Shively