starting up an engine CM400
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  1. #1
    Member arieon69's Avatar
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    starting up an engine CM400

    I pulled the following text from my project thread. I figured it may get more of a response here. The engine is off the frame, I'm looking to try and crank it up. Although I'm not 100% on how to do that. It's funny to me, I can work on cars and trucks all day. When it comes to motorcycles, even with the similarity, its like speaking Japanese. I only understand small bits.

    I opened the valve cover to Engine B. Now this one, I believe was running when pulled. Smells of gas and oil. Not stinky gas either, looks like is was just down for an oil change prior to removing it from the bike. Oil level is great. Nice color to it. This is the one I want to actually run.

    Now my question is, how do I go about doing that? The carbs aren't on it and I'd prefer an easy route of just spraying with starting fluid to see if it'lll run. What wire need to be where? Once I'm sure it may run, it'll undergo a light rebuild as I begin planning out these two frames.

  2. #2
    Super Moderator J-T's Avatar
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    You will need the CDI, coil, and associated wiring/connections. The black wire with white stripe coming from the CDI remains disconnected (grounding that wire is how you shut the engine off). No battery required.

    Assuming you don't have a kickstarter (or an engine mounting system that would allow it's use) you'll need cables from the starter to a solenoid and battery.
    JT
    81 CM400T Under re-construction
    82 GL500

  3. #3
    Senior Member doode's Avatar
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    Not sure how others will reply, but my thoughts are, instead of trying to run it on a stand, why not just test compression and actually run it on a bike?

    For the stand test, cdi, battery to hook up the starter motor, coils, headers...

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  5. #4
    Member arieon69's Avatar
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    I put the engine back on the bike, but I got everything in pieces. So I'm trying to put it back together to run it. I have the CDI hooked up, b/w wire disconnected. Coils hooked up to the CDI and plugs. The kickstart is there, but the arm isn't. I don't know where it is or if one even came with the stuff. For instance, I have 3 engines, 2 frames, and 1 gas tank. Lol. So now I'm thinning out my wiring, or trying to. While also trying to fire everything up.

    I want to bypass the ignition switch (no key), can I do that by just not plugging it in? Also for the Engine Run button? They had a toggle switch hooked up to the starter magnetic switch. Is that how I'll be able to start it? Forgive me guys, I'm kind of learning as I go. I've been tracing the wires on the diagram. With it running, I can slowly remove things and thin everything out. I'll be switching over to LED and probably 26650 A123 cells.

  6. #5
    Super Moderator J-T's Avatar
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    For the ignition you need a wire from the black/white wire to ground with a switch in it. You shut the engine off by closing the path to ground with that switch. Traditionally either the ignition switch or the kill switch can provide that path but any switch will work, it just needs to be open to run, closed to shut it off.

    The starter button serves 2 purposes. In it's normal position it supplies power to the headlight. When pressed it connects power to the starter relay and disconnects power from the headlight (so the starter gets all the available battery power). You could just wire the headlight directly from the ignition switch (or any switch you connect to the battery) and add whatever switch you like to power the starter relay though, personally, I would recommend a momentarily closed switch (one you have to hold to keep the connection closed) rather than a traditional toggle switch.
    JT
    81 CM400T Under re-construction
    82 GL500

  7. #6
    Member arieon69's Avatar
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    Since we're kinda on the topic. Below is the ignition switch I just bought. I was going for more of a turn key to run, this one is just a 3 way switch. On the back are 3 slots marks B, IG, L. Which I'm not sure how to interpret. Dealing with this wiring stuff, I feel kind of dumb.

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    Also with what you were saying, I can basically leave out that starter button all together by just manually wiring my headlight. Put it on a momentarily closed switch? I'm hoping to find a digital tach with a built in headlight switch.

    I wish someone just had pictures of their wiring, then it could all be so easy lol.

  8. #7
    Senior Member doode's Avatar
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    Battery, ignition, lights?
    When you turn the key, is there continuity between the b and ig and b and L?
    Nothing between ig and L though?

  9. #8
    Member arieon69's Avatar
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    it has yet to be installed. But that sounds correct to me. Wire colors to respective locations? I'm looking at the wiring diagram now. So I'll update in a sec to verify that they're correct.

    *EDIT*
    Battery - Black wire and Red wire
    Ignition - Black/White wire
    Lights - Brown/White and Brown wire

    But maybe you could lend me a quick hand. In the video link below they started the motor with a battery. One wire is connected to the starter and thats "HOT" correct? Where is the other one connected?

    Last edited by arieon69; 12-17-2016 at 02:56 AM.

  10. #9
    Member arieon69's Avatar
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    well just turned it over, not getting a spark presently.

  11. #10
    Super Moderator J-T's Avatar
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    The black/white wire from the CDI must not be connected to this switch. Instead of making an open circuit (required for the ignition to run) you are connecting it to battery power. That switch can be used to provide power to the lights, it cannot be used to control the ignition. For that you need a switch that provides a path to ground for the black/white wire from the CDI. When that switch is closed it shuts the bike off. The circuit must be open for the bike to run.

    BTW moved post to SOHC electrical, might get better help there.
    JT
    81 CM400T Under re-construction
    82 GL500

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