Motorcycle Repair: overheating, heat range, oil system

Question
Chris
A friend of mine has a 1979 Yamaha the motor was just torn down and re-ringed now that it has been put back together is seems to be running hot what will cause that?

Answer
Hi David.
 If the old rings were bad, then the motor was running colder than normal before the ring job.  With the new rings in the engine will have better compression and produce more heat than it did with the old, worn rings.  Also your friend may have noticed an appreciable increase in available power as well.

If you are comparing the running temp against the old temp, then don't.  Measure it against the temp that the repair manual says it should be.

If it is running hotter than is recommended by the manual, then flush the oil system and then use some higher heat range oil.

Let me know wht you find.
Good luck.
FALCON