Hello! I own a Gravely 260z which has a Kawasaki fh21v 25 horse engine on it. I have been told that it has bad valves. What would be my best option?
1. Replace entire engine (very expensive)
2. Replace half of engine ( I don't remember what this is called, help!!)
3. Rebuild the engine

Please help on best most cost effective solution. Thanks!

what is the problem??

Bad valves? theres no need to replace nothing other THAN THE VALVES and or valve seats...., if someone told you, you'd need a new engine, they are jipping you.

Burns a lot of oil.
Powers good until you power up the deck, then very little power.
You can take the right spark plug off and it keeps running.

2 cyclinder i take it.. Take the cyclinder heads off and clean carbon deposits on the piston head and 2 valves. Excess carbon could build up, hindering the valves from fully closing/opening. But thats my opinion.

If its buring oil too, rings could be worn out...