Rev and speedo needles going up and down

[uppo]

Hi!

Old post, but I am facing this problem now.
While I was driving speed and revs "needles" were dropping to zero, then crazy jumping and then again back to zero. This stopped when I turned on turn indicator. I stopped and when tried to turn on motorcycle it was dead (no signs). Previous owner had installed battery main switch (I guess he had faced similar problems as it is installed), I turned it off and on and then everything seemed fine again. I started motorcycle.

Would you suggest me to check contacts and tighter wires on battery? Could it be ECU?

Thanks!

[Disorderlypunk]

forget ecu that doesnt control your other electrics just engine timing really


your most likely facing a bad earth - had a similar problem on my old honda BROS just cleaned battery terminals on mine but likely to something else
- but what do you mean by battery main switch ?? if you mean like an isolator switch that kills the battery feed then i would definatly start with that
especially as you said you turned it off then on again and it was fine

[His Dudeness]

Hi!

Old post, but I am facing this problem now.
While I was driving speed and revs "needles" were dropping to zero, then crazy jumping and then again back to zero. This stopped when I turned on turn indicator. I stopped and when tried to turn on motorcycle it was dead (no signs). Previous owner had installed battery main switch (I guess he had faced similar problems as it is installed), I turned it off and on and then everything seemed fine again. I started motorcycle.

Would you suggest me to check contacts and tighter wires on battery? Could it be ECU?

Thanks!

Since the problem with the speedo and tacho are affected by the indicators I'd be looking at any common connections between those three components. From what I can see they share common connections at the battery, the ignition switch and they share a ground connection.  If someone has added a switch onto the battery that would also be a common connection and could be causing the problem or it could cause all the electrics on the bike to die. I'd probably start at that switch since it's not a factory item so it might have been done poorly. With the ignition on give that switch a wiggle and see if the bike turns off, also check for burned connectors or wires. Any of that would show a faulty connection. There should be no need for that switch. I'd guess someone added it as an additional security measure in case someone tried to steal the bike or it's possible if there's something drawing power when the bike is parked maybe it was put in to stop the battery going flat. Does the battery go flat if you leave the bike parked? Have any accessories been added? The fact that the extra switch is there shows someone's been working on the wiring so they might have caused a problem.

With the battery I'd be checking that the connections are tight and clean and that the battery is charged. With the ignition I'd check that the connector that joins the ignition to the main loom is in good condition. You said that your bike totally died? That could be caused by that ignition connector. To check the ignition connector properly you will have to follow the wire off the back of the ignition under the tank to a junction box. Pull the connector apart and check it for signs of burning. Also check along the ignition wires for any signs of burning where they go into the main loom. The other thing to check would be that the common ground connection that the dash and indicators share is good.