Question about 1978 Suzuki GS 750 E

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I've replaced the coils, spark plugs and battery. I've cleaned the carburretors. But the bike will still not start. What could be the problem?

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  • Truckbuilder Mar 17, 2011

    I have checked for spark and found a problem with the points that i just fixed.... I now have spark on all four cylinders.... I spent last night checking for compression.... and i have compression in the third and fourth cylinders, but nothing in the first and second.... after tearing the engine apart that there is a stuck valve.... so im going to clean everything and put it back together and see what happens from there......



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Did the bike run fine previously...or unknown history?

Does it crank the starter normally?

Have you verified with a grounded spare spark plug that the ignition is actually firing as you crank starter...if not...might be an interlock neutral light on...have you tried with sidestand up and clutch pulled in? Kill switch ON?
Usually the interlocks prevent cranking too but older bikes tend to get rewired by some ownerthats.

Not sure on your model, but some use vacuum operated fuel petcocks...if yours has them...have you tried setting them to PRI or prime position to fill carbs without vacuum?

Posted on Mar 17, 2011


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This bike has electronic ignition, if I remember correctly. Spark on one side indicates box may have failed or the trigger unit.. Try switching parts from one side to the other side, I.e. coil, plug, wires one at a time or if you have/can find good used or new parts to try. Are you certain all of the passages in the carbs are clean? If it starts and runs on one one cylinder by putting gas in cylinder, appears if your idle circuit is plugged or your choke circuit isn't working..

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Hi, Mario67 and the usual suspects are:
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      Make sure the key and kill switch are both in the "on" position. Ensure that the proper starting procedures for your bike are followed. Is it in neutral? Clutch pulled in? Gas in the tank? Then try to start your bike. Does it turn over? If not, check to see that the battery is properly connected and the terminals are not corroded. If they're loose or dirty, clean and tighten them. Then, using a voltmeter that measures ac/dc and ohms, check to see that your battery has enough charge to crank the engine. If not, replace or charge your battery and try again. If it still doesn't turn over, there may be a loose connection between your battery and starter; a bad ignition or starter switchl or a bad safety relay. Check a repair manual for proper testing procedures for your bike, as each motorcycle differs.

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    If you've followed these steps and still can't get your bike to run, call in an expert. If you think you've narrowed down the source of the problem, describe the steps you've taken to point the mechanic in the right direction.

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    I suggest replacing the cap and rotor (check the inside of cap for wear on the "points"
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    Remove both sparkplugs from engine. Plug them back in the sparkplug cables and let them rest on the engine.
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    -Same side of engine sparks: interchange the low-voltage connector at the ignition coils.
    Give it a try:
    Same engine side sparks: Replace the defective ignition coil.
    Other side of the engine sparks: Check the circuit harness for loose connectors, and/or Clean-replace the breaker points ( left side of the engine carter ).

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