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  1. #1
    CB750 Member esmeenge's Avatar
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    Apr 2019
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    Steps to Get It Running

    Hello,

    I am trying to figure out an easy way to get my 1976 CB750 running. I have a new harness, but I don't want to replace it until I know I cannot start the bike without replacing it. So, what are some steps I can take to figure out why my bike isn't starting, or steps to get it running prior to the harness change.

    I have tested black wires connected to the coil. No power.

    I have a red wire going into the white ignition switch that is detached from the housing(pictured) - that has power going to is. No other wires have power.

    How would I check the engine cut off switch to see if it is actually working?

    These are the only switches I can think of to check.

    I'm following this great diagram... http://oldmanhonda.com/MC/wiring750K1.html

    Click image for larger version. 

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  2. #2
    CB750 Addict pidjones's Avatar
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    Sep 2018
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    East TN
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    For a gas engine to run it needs fuel, compression, and spark.
    "Love 'em all.... Let GOD sort 'em out!"

  3. #3
    CB750 Member esmeenge's Avatar
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    Yes, so, how do I eliminate them? Which one do I have and do I not have?

    I'm sure I have compression, I'd be surprised to have a bike that ran last year not run do to compression.

  4. #4
    CB750 Addict pidjones's Avatar
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    Sep 2018
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    East TN
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    Are plugs wet? Exhaust smells of gas? Must be getting fuel. Do plugs spark (nice, hot blue spark, not just a whimpy yellow spark)? Almost every older CB needs vlave clearance checked and corrected, carbs properly cleaned and parts adjusted/renewed as needed, and ALL electrical connections cleaned and tightened. Sorry, there are no short cuts or single common failures that I've seen. A by-the-can-instructions use of carb cleaner like Seafoam can help after a winter layup of a good running bike, but it has to run first. If not used to the extent of several tanks of fuel every year, you may also need to drain and clean the fuel tank.

    BTW, download the factory service manual and wiring diagram, take a multimeter (if you don't know how to use one, take a DC electronics course) and go through your entire existing harness. You won't get piwer past the red wire until you turn the switch to Run, which you won't know until you assemble the switch.
    "Love 'em all.... Let GOD sort 'em out!"

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