For cool engine,
1. Remove all extra mud guards.
2. Keep engine clean, remove any mud from tappet covers and bottom etc.
3. Keep good tuning, good air fuel mixture in carb.
4. Full tire pressure. 30-40 at least
5. Dont drive above 60 in 4th.
6. Dont carry a passenger all the time.
7. Turn engine off at red light.
8. Air filter should be clean.
9. Petrol should be good.
10. Engine oil level near full mark.
11. Regular engine oil change every 1000 km at most.
12. Good tappet adjustment.
I can come up with these points to keep engine cool.