Yamaha rpm gauge

[CaptainRick]

I run two Yamaha 9.9's. Each has a seperate rpm gauge. Both gauges read approximately 2400 rpm's at full speed. I think they should read about 4800. They appear to read about half the trus value. What might the problem be?

 

[rodbolt]

Re: Yamaha rpm gauge

check the tach pole setting on the tachs, should be set to 6 pole.
what brand tachs are they ?

 

[rodbolt]

Re: Yamaha rpm gauge

hit the button to fast, anyway if they two stroke it should be set to 4 pole.
there again no model number and all we can do is guess.
since 84 when yamaha has been imported to the US there have been at least 10 models/variations in the 9.9.
but 2 stroke tach sets at 4 pole and F motors set at 6 pole since about 1994.