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Thread: Tachometer for bike

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    Default Tachometer for bike

    Salaam to All:

    I have managed to installed tachometer in my 70 CC bike. Actually it was made for CAR and now in bike it is showing some RPM when engine is running.
    I made tachometer as 1 electrical pulse per revolution and it is showing 4000 RPM on idle which I think is not correct for bikes (correct me if I'm wrong) so it requires some calibration for proper working.

    Can some body tell me what is pulses per RPM relation for 4 stroke 70 CC bike or what is calibration factor when using car tachometer in bikes.


    Regards

    !! DIY in a professional WAY!!

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    In 4 stroke single cylinder engine, one pulse per two revolutions.


    Sent from my iPhone using Tapatalk

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    Quote Originally Posted by aiktoonamila View Post
    In 4 stroke single cylinder engine, one pulse per two revolutions.


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    Thanks

    As I stated, I configured my RPM meter for 1 pulse per revolution. (e.g 50 Pulses /sec=3000 RPM). The meter is displaying about 4000 RPM (stable) on idle. Considering one pulse per two revolutions it will display 6000 RPM (???) (for same input pulses) which is again high on display (incorrect for Idle?)
    Is there any other problem in measurement technique or my RPM meter is not showing correct RPM?

    The same RPM meter works OK for my car
    !! DIY in a professional WAY!!

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    No, take it vice versa. Your instrument should generate pulse after completion of two revolution. That will show ur RPM equal to 1500.
    BTW from where u r picking pulse ??? From input of HT coil ?? Or somewhere else ?


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    Quote Originally Posted by aiktoonamila View Post
    No, take it vice versa. Your instrument should generate pulse after completion of two revolution. That will show ur RPM equal to 1500.
    BTW from where u r picking pulse ??? From input of HT coil ?? Or somewhere else ?


    Sent from my iPhone using Tapatalk
    So rpm will showing 2000 RPM for bike idle.

    I'm taking tach signal , black with red line on it, from wire coming from/to trigger. I don't know what to call it. There is connector with wires from engine coil side. I have connected tach to of connector wire...
    !! DIY in a professional WAY!!

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    There is High Tension coil, from where the plug wire comes. U will find a wire connected with this coil with a connector. U will use this wire to pick a pulse for your tachometer.
    Each single pulse will ensure that your crank shaft has revolved two revolution.


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    Quote Originally Posted by aiktoonamila View Post
    There is High Tension coil, from where the plug wire comes. U will find a wire connected with this coil with a connector. U will use this wire to pick a pulse for your tachometer.
    Each single pulse will ensure that your crank shaft has revolved two revolution.


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    Thanks,
    I will trace and will update you
    !! DIY in a professional WAY!!

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    You will have to use a current limiter ( resistance) etc with this wire.


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    interesting.. I added a tach-o on my 200cc new engine and used a rickshaw meter and wired it just as in the guidelines I found in the box of meter and it idles perfectly on 1500~1800RPM ...

    I absolutly had no idea that we have to calibrate it also.. it just worked out of the box as it was for single piston engine .... can u explain a bit further how you calibrated the pulse with tacho ? asking just for knowledge..
    https://www.pakwheels.com/forums/motorcycle-travel-diaries/277725-sober-riders-visit-khunjerab-adventurous-way-via-nori-pass

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    here is the meter ...pic is little blured and shiny but u can notice it is idling at 1.5 RPM nicely...

    the road ahead bike is all swiped due to mirror effect of wind shield of bike..

    Tachometer for bike -1467446
    https://www.pakwheels.com/forums/motorcycle-travel-diaries/277725-sober-riders-visit-khunjerab-adventurous-way-via-nori-pass

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    Quote Originally Posted by aiktoonamila View Post
    You will have to use a current limiter ( resistance) etc with this wire.


    Sent from my iPhone using Tapatalk
    Thanks.
    I already added resistor to limit current otherwise excessive current causes shutdown engine since CDI not getting required current.

    I have traced spark trigger wire from engine coil (not ignite coil) this wire is going to CDI module.

    I'm using this wire as tach signal. Now the idle speed is about 2000 RPM and it is stable if accel is not touched.
    This is minimum setting with idle adjust screw below this setting engine start dying.

    Now my concern is weather this idle RPM normal ? I hv read some where idle RPM should be 1000 -1200.

    What would the reason for this almost double RPM display .
    Do I further need pulses divide by 2 to get 1000 RPM on idle.
    !! DIY in a professional WAY!!

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    Yes, idle RPM is aprox 1250. U have to divide it by 2 to get accurate RPM. U can calibrate by comparing it with the meter as mentioned by Vickytulla.


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    Quote Originally Posted by vickytulla View Post
    here is the meter ...pic is little blured and shiny but u can notice it is idling at 1.5 RPM nicely...

    the road ahead bike is all swiped due to mirror effect of wind shield of bike..

    Tachometer for bike -1467446
    Your tach looking nice and is good addon to bike.

    My tachometer is self made and is digital type therefore it can be configured for any engine cylinder.
    I will also share pics soon of digital tach...
    !! DIY in a professional WAY!!

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    Quote Originally Posted by uetian04 View Post
    Your tach looking nice and is good addon to bike.

    My tachometer is self made and is digital type therefore it can be configured for any engine cylinder.
    I will also share pics soon of digital tach...
    Please do share the details. I may get interested in one for my cg 125. Have you tried a digital speed meter?

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    Brilliant engineer... can you share you making experience and how was the result ? Would love to see it working on 125 as u said..



    Quote Originally Posted by uetian04 View Post
    Your tach looking nice and is good addon to bike.

    My tachometer is self made and is digital type therefore it can be configured for any engine cylinder.
    I will also share pics soon of digital tach...
    https://www.pakwheels.com/forums/motorcycle-travel-diaries/277725-sober-riders-visit-khunjerab-adventurous-way-via-nori-pass

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    1000~1200 is for cars IMHO as I far as I know bikes are high rev engines then cars or bigger vehicles and reguire at least a 1500 RPM or like in my case the manufacturer say 1500 ~ 2200RPM is Ideal for idiling.
    https://www.pakwheels.com/forums/motorcycle-travel-diaries/277725-sober-riders-visit-khunjerab-adventurous-way-via-nori-pass

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    @FM3o5 added a tachometer to his bike maybe he can also help you

    Tachometer for bike -1467746

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