Motorcycle Repair: valves, honda shadow 750, micro torch

Question
I have a 1986 Honda Shadow 750 wit 75,000kms on it. I was problems with the fan and the engine ran into the red on the temperture gage , the antifreeze wasn't boiling over,  I put on  a manual switch to activate the fan, My G/F was learning on the bike doing fig 8's and didn't realize it was in the red, so i turned on the fan and kept the engine on a high idol till it went back into the safe area on the gage , the next morning i realized tapping high end tapping in the motor, the bike runs well but the idol seems a little irratic .... What could be causing this and is there a fix for it ????? Heavier oil or a oil additive to fix this problem or have i caused damage ....

Answer
Its possible that some damage may have occurred. There are two temperature senders on this bike.One is on the engine for the gauge the other is usually found on the left side of radiator for the cooling fan,sometimes the switch shorts out and wont turn on the fan. Try a test light on the wires to the switch to see if you have power. If you have power on 1 wire the only way to really test the switch is to heat switch in hot water or small micro torch to see if the other wire powers up. It may need to be replaced.For now try heavier oil in the engine a long as the outside temp is around 70 Try a 40 or 50 weight non detergent oil to get some more life out of the bike.