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Tachometer issue - constant high reading

Discussion in 'Technical and Troubleshooting Torque' started by neogeo, Dec 20, 2011.

  1. Hi Netriders!

    Problem: Tachometer reads consistently high. E.g. it reads at 13-15k rpm when it feels like engine is actually doing only 6-7k rpm.

    Me: Not a mechanically savvy guy but I did
    - try to understand this without much luck,
    - and also had a mate of mine attempt to do this without the best of luck either.
    Bike: Kawasaki ZZR250 91'
    Mods: None (as far as I know)
    Other issues: None – everything seems to run smoothly otherwise.
    No. of Owners: Unknown (suspecting 5-10)

    On start up
    1. I use the choke for 5 mins warm bike – tacho reading: 9-11k rpm
    2. After the 5 mins it idles at tacho reading : 3-4k rpm

    On travel
    1. At 5th gear, it reads about 16-18k rpm to reach 80-90km/h on flat road. (though it feels and sounds like only about 8-9k rpm)
    2. At idle, it reads 3-4k rpm.

    Has anyone experienced similar problems?

    Any insight/sharing would be greatly appreciated!

  2. As you have seen from other forum this seems to be a common enough problem although like you I can't see any immediate solution. The tacho is an electric one based on a signal from the engine management. If the bike is running Ok the the Engine management is OK. Go through and check the connections again. Unplug and replug the connector into the Engine management and give it a clean if the connectors look dirty. Check there is no moisture in that connector and the connector that plugs into the tacho itself. Give the plugs a spray with some water displacement such as WD40 before you plug them back together.

    If all that fails it may be a faulty tacho unit itself.

    Below is the tacho circuit for a 97 ZZR250.

  3. Thanks cjvfr.

    Definitely giving it a shot.