Motorcycle Repair: Tach problem, yamaha yzf600, gas tank

Question
My tachometer has been having problems the last couple of days.  Either on the freeway or sitting at idle the tach will sit at 0 RPM for 3 seconds, jump to 8,000 RPM for 3 seconds, then drop down and show the actual RPM for 3 seconds, then repeat 0/8/actual.
I recently pulled my gas tank off and even with a towel below it some gasoline dripped on the engine, so after work I washed the engine with a hose.  I dimly remember something like this happening 4 or 5 years ago I think after washing my bike, but it cleared itself up after a couple of hours and ran normally.  Unfortunately it hasn't fixed itself this time.  Any ideas?
1997 Yamaha YZF600

Answer
Hi Chris,

I suspect water shorting is the cause of the problem. If so, the moisture should evaporate in time.

Consider applying dielectric grease to electrical connectors. Doing this helps prevent water shorting and corrosion.

If the problem persists, I would have a local Yamaha shop inspect the CDI (engine control module).

Respectfully,
Mark Shively