[sfenn99]

Hey Guys....just hit 150 hours on my EXC500 and its never run better.

Religiously change oil ever 15 hours and at same time run through the whole bike (outside of cracking motor) to check/fix anything else that may not be working properly.

Just noticed that the manual is calling for replacing the piston at 135 hours.
Is this something that most do or is it KTM being over the top with preventative maintenance?

Have a 2013 350 EXC-F 630 hours, 13,000 miles. All original internal parts except for DT timing chain tensioner early on. Oil change and filter every 15 hours Motorex, multiple air filters AND TwinAir dust cover/pre filters rotated often. Valves stayed within specs except one time had to change 2 shims. Leakdown was single digit until recently, now at 16%. Bad, poor, surprised. Air leak noise from crankcase, top of open cam area, since valve cover was off. But going to test again because just read about possible valve guide wear then bad valve contact. Will listen carefully at exhaust and intake. Latest symptom is very hard to start cold. Newish symptom. Runs great though.
Opening up engine soon. Collecting parts. All new OEM valve kit, plan on new piston (at least) and rings but want to see if cylinder bore is good or bad, for possible replating or new cylinder. Will check for top of rod wobble, crank clearance as far as I can check.