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Thread: OKI MPS-200

  1. #1
    CB750 New Member Venca80's Avatar
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    OKI MPS-200

    Perhaps a stupid question, but is there a difference in OKI MPS-200 ignition units used on different Honda motorcycles (such as the HONDA CB750KZ and Goldwing) or is it one type with the same parameters and are therefore mutually interchangeable?

  2. #2
    CB750 Member Changa's Avatar
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    Wondering the same thing.
    Literally just took mine out as they are both melted and not sure if they're working right....mine is MPS-200 as well.

    Thought I'd give your question a "bump"

  3. #3
    CB750 Guru amc49's Avatar
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    Early ones used a potting compound that melted way too easy, it usually does not hurt the units at all. If the underside still appears to be completely coated they are OK, tar based still insulates the components even in a thin coat. I used melted ones for 15 years, they melt in summer even when not being used.

  4. #4
    CB750 Member Changa's Avatar
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    Well.....I'm trying to figure out why cylinders 2 and 3 don't seem to be firing right. I put a timing light on all 4 leads.....1 and 4 are nice and constant beam. 3 and 4 is another kettle of fish.

    So....today I decided to check the coils. Isn't it fun trying to find You Tube videos on that. Finally found a guy testing a GL1200 set of coils.
    In any case, seems my primary/secondary side on the coils is -

    1 & 4 - 3.6 ohms / 12.8
    2 & 3 - 3.6 ohms / 11.8

    Don't suppose anyone can tell me if this is in range ? Tried finding the range in my workshop manual and online....I must be dumb cos I can't find it. 1979 CB750k. DOHC.
    Next I'm going to try a test on these igniter things. (and yep.....mine have melted away at the back.)

    Peter
    Last edited by Changa; 10-09-2019 at 01:11 AM. Reason: I typed wrong stuff cos I was busy.

  5. #5
    CB750 Guru amc49's Avatar
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    Swap the coils in the wiring, if the problem switches it's a coil issue.

    Uh, it's 1-4 and 2-3 there, there is no 3 & 4.

  6. #6
    CB750 Member Changa's Avatar
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    Yep....2 and 3. Was in a rush when typing.

  7. #7
    CB750 Member Changa's Avatar
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    OK......just putting it out there again......can someone possibly tell me the resistance readings for ignition coils on a 79 CB750K ?

    Have looked around, can't find it. Found info from guys with GL1100's.....not certain if they're the same...…

    Thanks.

  8. #8
    CB750 Guru amc49's Avatar
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    http://www.cb750.com/threads/6370-seat-removed

    Go to post #3 and do what I told that guy to. There is an ignition section.

    Be aware that low volt testing like you want to do will not necessarily point out possible semi-shorts in windings that do not show up until the coil is really stressed, as in actual use. Meaning if there is a spot where wiring is worn to almost be a true short, the coil can turn it into one at high voltage as the spark shorts inside the coil windings to greatly lower the outside spark at plug. A simple resistance check may not show that at all.

    Another test is plugs and plug wires installed on one coil and metal base of plugs well grounded. Switch power to on on black/white wire on that coil and simply touch the blue or yellow wire to ground for a few seconds then quickly break the connection. The coil will spark if good. The system is a waste spark one, BOTH plugs must be well grounded or NEITHER fires correctly, one coil fires backwards and normal. Plug ground path is out through one plug and goes into the other to run up it backwards.

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