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Discussion Electronic Compression Gauge (DIY)

Discussion in 'Maintenance' started by maelstrom, Jul 14, 2020.

  1. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    So one of the forum members mentioned the issue of the long hose on a compression gauge recently and it got me thinking. On a 250cc 4 cylinder the compressed volume is only about 5cc so the volume added by the hose etc is going to make a big difference. On a 3 litre 6 cylinder car engine no biggie, but for us it is.

    Anyway chatting with my Aussie friend this morning and we think why not use a pressure transducer. Since I am an not an electronics god, I thought I would throw it open to discussion.

    Example:
    Honda MC22
    Plug thread: M10 x 1 x 19
    Make an adapter to screw into the plug hole and the other end to take the transducer with a small diameter bore hole. You could just use a multimeter with a max function to take the reading and convert to pressure. Of course that could be made more flash with LED displays etc.
    Here is a quality item (Honeywell) and of course there will be lots of cheaper variants available.
    PT.jpg
     

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  2. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Turns out you can buy a sensor in 10 x 1 anyway, too easy.
     
  3. ruckusman

    ruckusman White Mans Magic Master Premium Member Dirty Wheel Club

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    Very feasible, I did do some research into DIY vacuum gauge carb balancers - there's some great projects out there however good quality MAP sensors aren't cheap

    What's the price range of these sensors?
     
  4. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    The one I showed is about 60 USD. I have zero interest in electronic vac gauges, one fault and you are forever doing everything wrong.
     
  5. Andych

    Andych Moderator Staff Member Premium Member Contributing Member Dirty Wheel Club

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    Given the small capacity I am not a big fan of compression testing bikes at all.. For those who have the experience and inherent knowledge to utilise any data derived from what is essentially a flawed system (unless you spend mega bucks) it can be a useful tool.. I prefer to use a leak-down testers as it gives a much better indication on where or what the problem may be and the relatively in-expensive (read Cheap Chinese) testers on the market are fine for the vast majority of what we would do.
    The problem with electronic pressure sensors is translating the figures you get into worthwhile numbers.. they are sensitive enough to monitor atmospheric pressure. By the time you frigg around with adapters etc you will have spent a lot more than on a Leak-Down tester and still may not have any idea what the figures end up meaning...
    Just my personal opinion though...

    Oh.. and I personally think this item is really good value for multi cylinder machines..
    https://raytechautomotive.com/products/synchroking-4s-mkii
     
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  6. maelstrom

    maelstrom LiteTek Staff Member Premium Member 250cc Vendor Contributing Member

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    Agree 100% with leakdown testers. Have used them forever.
     
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