Motorcycle Repair: 1987 Yamaha FZR 1000 Temperature Gauge, yamaha fzr 1000, 1987 yamaha fzr 1000

Question
1987 Yamaha FZR 1000 Temp gauge jumps around and won't maintain constant reading while bike is running. Seems to be worse at higher revs.  I have tested both sending unit and gauge using shop manual procedure (heat sending unit in water and read resistance with meter -- ground sending unit lead to frame to peg gauge) and both seem ok.  Have also flushed cooling system and replaced coolant. Bike is otherwise in excellent condition and runs very well. I hesitate to replace the gauge without knowing it is bad -- costs $100.00+.  Thanks in advance for your help.  George Brown  podlogic@verizon.net

Answer
Hi George,

This is one of my favorite motorcycles.

I suspect the gauge is defective. This is the first I've heard of such problem.

Cooling systems are designed to be air free. Be sure to purge the cooling sytem of air. Use a tool such as the  AirEvac tool by MityVac.

Respectfully,
Mark Shively