Directly from the owners manuals (KTM owners manuals can be downloaded from
here)
KTM 500 EXC
Full Oil service (includes many filters, etc.) every 10 to 15 hours.
Valve checks every 30 hours.
Engine rebuild (replace all bearings) at 150 hours, (70 hours if raced)
KTM 690 Enduro (LC4)
Full Oil Service at 10k km (6200 mi.)
Valve checks at 10k km (6200 mi)
No recommendation for engine rebuild
Suzuki DRZ 400
Oil Changes at 6k km, filter changes at 18k km (11k mi.)
Valve checks at 24k km (14.5k mi.)
No recommendation for engine rebuild
(Converting hours to miles: A dual sport bike will average only about 30 to 40 miles per hour in use. So 15 hours is about 525 miles and 30 hours is about 1,050 miles. KTM expects the EXC rebuilds after only a little more than 5k miles of casual use, or only 2500 miles of racing. Obviously people often do much better than that, but 10k miles between engine rebuilds is not uncommon. The LC4 is much more robust than the smaller bikes.)