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Discussion Starter · #1 ·
When the spark plug wire is snapped onto the plug, nice and snug, the plug doesn't fire, and the bike runs on the front cylinder only. When the wire is hanging on the plug wavy gravy, the plug fires, and the bike runs fine. I tried different wires on the plug, and I tried a different plug, and even though the resistance of the coil tested good with a fluke, I swapped it out anyway with a coil from another bike I have. What do you think?

Oh, here's my "other" ride ...

 

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Not familiar with Harleys,I ride a Katana ... but generally, if you hold the plug wire off the plug, making the spark jump the gap, and the cylinder begins to fire, its usually a fouled plug.. either oil or carbon or fuel fouled ... but if you put in a new plug and wire and its still doing it,it would seem to be weak spark
 

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Discussion Starter · #6 · (Edited)
Compression ? Some times the valves need set ?
Not familiar with Harleys,I ride a Katana ... but generally, if you hold the plug wire off the plug, making the spark jump the gap, and the cylinder begins to fire, its usually a fouled plug.. either oil or carbon or fuel fouled ... but if you put in a new plug and wire and its still doing it,it would seem to be weak spark
The plugs do foul once the bike runs a while- even new ones. The compression seems ok but I do have to actually check it with a compression gauge. I'm leaning towards sticky valves because years ago, for the first ride of the season, the bike would act like this- run on 1 cylinder - then clear up and no probs after that. This time, though it's not clearing up. But why would the plug only fire when the spark jumps across if the valves stick or the compression is weak?

Thanks, gents. :thumbsup3:
 

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Discussion Starter · #8 ·
don t know about Harley ignitions, but is there anything similar to the Pick-up coil in a GM distributor? I think its ignition related..
Well, I ran a new wire between the points in the distributor and the coil. I swapped the coil with one I know works. I changed the points, condenser, wires, and plugs. Plug and point gaps have been double checked. Timing has been checked and double checked. Ignition-wise, I think I ran the gamut. Tomorrow I check compression, and valves, and seats. Since I don't know what it is, I have to find what it isn't. Thanks for the input.
 

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The plugs do foul once the bike runs a while- even new ones. The compression seems ok but I do have to actually check it with a compression gauge. I'm leaning towards sticky valves because years ago, for the first ride of the season, the bike would act like this- run on 1 cylinder - then clear up and no probs after that. This time, though it's not clearing up. But why would the plug only fire when the spark jumps across if the valves stick or the compression is weak?

Thanks, gents. :thumbsup3:
By leaving the plug wire loose on the plug you are increasing the gap that the coil has to jump across or to say another way you are increasing the voltage output of the coil . Due to the larger gap the coil must work harder to jump across it. Typically when a flooded engine (from gas) doesn't start the mechanic would pull the coil wire away from the dist terminal to increase the coil voltage and usually the extra voltage is enough to get the engine started again. I would check the plugs one more time . Check for incorrect gap, cracked insulators, incorrect heat range or maybe your fuel mix is too rich.:thumbsup3:
 

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By leaving the plug wire loose on the plug you are increasing the gap that the coil has to jump across or to say another way you are increasing the voltage output of the coil . Due to the larger gap the coil must work harder to jump across it. Typically when a flooded engine (from gas) doesn't start the mechanic would pull the coil wire away from the dist terminal to increase the coil voltage and usually the extra voltage is enough to get the engine started again. I would check the plugs one more time . Check for incorrect gap, cracked insulators, incorrect heat range or maybe your fuel mix is too rich.:thumbsup3:
He only has one cyl. doing that , so He needs to ck the compression !
 
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