Tach

[bajabreeze]

I have a 1986 1TX FJ1200. At the end of last season, the tach started to act erratically now it will just bottom bounce at 0-2000rpm regardless of the RPM. Any thoughts where to start on this to narrow it down?

[PaulG]

I have an intermittent problem with my tach sometimes on my '92.  It will suddenly read double the actual rpm's.  Check the wiring diagram and trace where the signal comes from.  It took me a while to trace it but found that the wires that eventually connect to the ignitor box via the coil (I think - been a while since I last checked) had some corrosion on the connectors.  This usually happened under damp conditions, i.e. dewy mornings, or after an extended rain - but never while riding in the rain.  I have no garage so during riding season the bike is parked outside under a cover.

That might be one place to check.  I gave the connectors a rub with some emory paper and a dab of dialectric grease, and the problem went away for about a year.

[Pat Conlon]

Sitting on the bike, the left coil powers cylinders #1 and 4, the right side coil powers #2 and 3.
On the right side coil, there is a grey wire. That is the wire that signals your tach. Over the years those coil connectors accumulate a lot of gunk, including the coil ground wire. Clean those connections, see if that helps.