Help with intermittent spark - 78 KZ400 - KZRider Forum - KZRider, KZ, Z1 & Z Motorcycle Enthusiast's Forum

Help with intermittent spark - 78 KZ400 19 Jul 2018 19:30 #787241

Stockton350 Topic Author Offline User Posts: 17 Thank you received: 1	When I check for spark (spark plug in the boot, plug against the engine case) I sometimes get spark and sometimes don't. Battery is full, boots and plugs are new, checked point gaps, new coil checks within specs. I also made sure the ground battery terminal had a good connection to the frame. Any suggestions? 1975 CB125 \| tinyurl.com/jds9l7q 1976 CB350 1978 KZ200 \| tinyurl.com/j3odxo8
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Help with intermittent spark - 78 KZ400 19 Jul 2018 20:07 #787242

One1 Offline User KZ 750 FOUR Posts: 64 Thank you received: 3	Run a separate ground to the engine block. As the mounts age and become rusted from the inside out it's possible to loose contact between the frame and block. Vulcan 750, KZ750, KLX 125, and many more......
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Help with intermittent spark - 78 KZ400 19 Jul 2018 20:21 #787244

650ed Offline User Posts: 15344 Thank you received: 2828	Stockton350 wrote: ................ I also made sure the ground battery terminal had a good connection to the frame...... Frame? I'm not familiar with the KZ400 setup, but the KZ650 ground cable attaches to the engine. Ed 1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Help with intermittent spark - 78 KZ400 19 Jul 2018 22:07 #787248

One1 Offline User KZ 750 FOUR Posts: 64 Thank you received: 3	650ed wrote: Stockton350 wrote: ................ I also made sure the ground battery terminal had a good connection to the frame...... Frame? I'm not familiar with the KZ400 setup, but the KZ650 ground cable attaches to the engine. Ed 400/440 attaches to the frame right beside the battery. cable is 4 inches long. Vulcan 750, KZ750, KLX 125, and many more......
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Help with intermittent spark - 78 KZ400 21 Jul 2018 16:10 #787356

VTEC
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Posts: 558
Thank you received: 80

Check the voltage drop on the power feed to the coils. There's an accumulation of lost voltage there including the ignition switch, kill switch, and all the old connectors in between.

Next time you have no spark check the voltage at the coils compared to the battery. The difference is voltage drop. You may even have nothing due to an intermittent open in the circuit.

KZ1000-K2
ZRX1100
XR400R

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Help with intermittent spark - 78 KZ400 21 Jul 2018 19:21 #787368

Fischer779 Offline User My bike runs on the tears of bald eagles Posts: 9 Thank you received: 2	Did you check the Plug Gap? Spark plug gap may be different on new plugs. Might want to check that and remove a variable. YZ400f "dual sport" KZ400D 95' Corvette
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