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Thread: The essentials test harness

  1. #1
    Join Date
    Apr 2012
    Location
    USA
    --
    4,114

    The essentials test harness

    I had an idea recently after getting another machine with a completely trashed harness. I should be able to build a "race style" harness that can be reconfigured for different machines. Wouldn't be ideal for actually using the harness, but just to get an engine running and the bare min working to make a machine run/move is sometimes a big step on a build. I figured if I put the effort into designing and building one of these for myself, I'd check what kind of other interest there would be. I can't say it will cover every make and model, but I'm sure I can make it work for most Honda 3 wheelers atleast. The exception is the machines with the round CDI connector, 84-85 just because that connector is out of production and haven't found an aftermarket source yet.

    To boil the harness down, there's roughly 6 wires needed to make most machines run. Some machines have safety systems that need to be satisfied, but the essentials are all hooked to the CDI (no lights, no battery charging, etc). My basic concept is the CDI connector is just a short sub harness with all the same bullet connectors on the end. Then there's different leads to connect the different parts. The user would have to be confident with following a color code chart based on make/model, or following wires in a wire diagram to get the wires hooked to the right spots. Just for a simple example, there's 2 main ignition coil setups, a ring terminal and a female spade, or two female spades. Engine (stator, pulse generator, etc) connections are where things go a bit wild and most of the adapters would be to match the engine to the CDI. I'm not 100% sure what route to go for the ground wire since it has to ground to the engine ultimately. Could use a ring terminal like OEM and have to bolt it up to test with the harness, or maybe add a small battery clamp as an option so it's a bit faster to use.

    Anyway, the concept is simple, I have to run through a bunch of models to make sure what I have in mind will work.

    Also, most machines that run the round CDI connector have another OEM CDI that has the same or similar spark curve, but runs the newer common 4+2 style CDI connectors. Like the 200es (and a ton of other models) have the China CDI's as an option, the 83 200x, or the 86 200s (and similar machines).

    I think price wise it will be $200 or less. Of course this is more geared up for a shop or someone that likes to mess with these than the person that only has one machine. My idea is you can completely bypass the trashed harness to test the machine and atleast rule one thing out of the mix when troubleshooting.

    I'll add photos and such as I work out the best ways to do things. Ideas and comments are more than welcome. Figured I'd atleast have a thread with my idea so I can't forget it =).

  2. #2
    Join Date
    Nov 2019
    Location
    Florida
    --
    1,044
    Hey Ps2fixer, I love the idea, if I may,could there be a circuit board with led lights, they would light green if the circuit was correct and the amp/volt were with in spec.
    I guess something that could plug in at the cdi box and when you spun the engine, all green lights would mean good to go,and say a red light on the coil or stator would say that circuit was bad. Just a thought. I do ohm out the main plug at the cdi box, I verify each component is in spec. I was just thinking of a little black box with visual indicators.

    Good to see you again.
    Mrc.
    mrc_builds on YouTube Channel

    https://www.youtube.com/channel/UCmw...confirmation=1


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  3. #3
    Join Date
    Apr 2012
    Location
    USA
    --
    4,114
    I've thought about a tester kind of like that, but it would require a micro controller, and each circuit tested would effectively need an ohm meter circuit made, and the low ohm ones have to be extra accurate. The biggest problem is having to configure the device for each model since the specs change quite a lot across models. It would be almost pointless to make a low accuracy tester just to say "if" there is power etc, since there's a spec to go by. Kind of like battery power, 11v will light up a test light, but it's a dead battery, a volt meter will tell you it's 11v and if it's "smart" it will say it's low/dead for a 12v battery.

    The thought I've put into the tester pretty much boils down to disconnecting the CDI box, and connecting the tester, telling it which machine it's hooked to, and take the ohm readings. It would cycle through the different items and spit out what it can detect from the CDI plug which should cover 90%+ of common electrical issues.

    This kind of tester would require me to design and built a circuit board and such, and I also think it would get pretty costly for something that effectively does exactly what a person with a multi meter can do with good instructions on where/how to test.

    On the other hand, the reconfigurable harness I think could be an interesting idea. I need to give it a shot some time, but been really busy lately. That 350d is still sitting non-running and I haven't diag'ed the issue yet >,<.

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