rpm needle randomly drops by 1000-2000 // s2r 800

[pmazdan9]

Hi, got another problem with my 2005 s2r 800.

On a very rare occasion the rpm needle drops down. I mean it idles at 'below zero' rpm (as if the bike was turned off). When riding, it shows wrong rpm (about 1000-2000 less than what it is) but the bike runs fine, there's no loss of power or anything. When I turn the key off and on again, it's back to normal and works fine. Needle goes smoothly all the way up and down when key turned and it shows correct rpm.

I always check the rpm at start up and it always shows correct rpm then, so it seems to happen during the ride. It's hard to tell when exactly (if not randomly), I normally go by the sound so don't look at the dash very often.

It happened maybe 3-4 times in 2.5k miles time (since I got it) so it is very rare but want to get it sorted. Any ideas?

[koko64]

Besides suspecting an actual loose connection within the tacho, I would check all wiring running out of the tacho to the ECU/ignition sub loom.

[pmazdan9]

Besides suspecting an actual loose connection within the tacho, I would check all wiring running out of the tacho to the ECU/ignition sub loom.

Just looked at the wiring diagram, R/Y cable at instrument panel/ignition switch is the rpm sensor. I'll check it out later!

[koko64]