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81 440 ltd 09 May 2023 05:28 #884436

  • Tannerlee92
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Purchased a bike from a neighbor. He had the bike sitting a good five years or more non running. I got it to the garage, to kers around a bit. Bypassed the ignition switch as there is no key. Cleaned carbs a bit tested electrical system with 12v test light. Seems to check out. Problem I'm having is no spark once the bike warms up. Any advice/tips things to check for. Wiring looks to be in good shape and when the bike is cold/warming up has all the ponies I do notice it misfires a bit when coming back down from WOT.

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81 440 ltd 09 May 2023 14:35 #884449

  • TexasKZ
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How do you know there is no spark? 
The problem could be that it runs out of fuel due to a clogged or improper filter, improper fuel level in the carbs, a malfunctioning fuel valve (petcock), a clogged fuel tank cap vent, and such.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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81 440 ltd 09 May 2023 19:16 #884460

  • Tannerlee92
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I tested spark with test light as well as placing them on the heads while cranking. Fuel delivery is fine, carbs seem to be in time with each other as well. Once the bike is to op temp it just cuts out it doesn't bog or miss or lack power it just dies. When that happens I pull plugs and test for spark gives off nothing. Let the bike cool and spark is back. I have continuity from the positive and ground circuits. Voltage readings are at or above 12v.

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81 440 ltd 10 May 2023 00:45 #884466

  • Wookie58
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If you have close to battery voltage at the coil positive and the negative side of the coil is being pulsed by the CDI/Points and you still have no spark I would suspect either the HT leads or coil itself is breaking down when hot

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81 440 ltd 10 May 2023 07:31 #884475

  • Nerdy
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I came in here to say it's almost certainly the coil. As it continues to fail, the bike will probably run for less and less time before losing spark.

 
1979 KZ400 Gifted to a couple of nephews
1967 Yamaha YCS1 Bonanza
1980 KZ440B
1981 Yamaha XT250H
1981 KZ440 LTD project bike
1981 GPz550
2013 Yamaha FZ6R
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81 440 ltd 10 May 2023 15:37 #884498

  • TexasKZ
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In that case, I too will vote for a bad coil.
1982 KZ1000 LTD parts donor
1981 KZ1000 LTD awaiting resurrection
2000 ZRX1100 not ridden enough

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