No spark at plugs - Honda Rebel Forum
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post #1 of 5 Old 04-14-2019, 05:02 PM Thread Starter
Join Date: Apr 2019
Posts: 2
No spark at plugs

I have a 1993 honda 250 nighthawk that all of a sudden overnight after a long hard ride to daytona bike week that following morning wood only run on one cylinder and now it won't start. Got new cdi and 2 ignition coils but still nothing. Can i use the complete wire harness from a honda 2017 pcx to make sure no small wire issue is the problem.? Or at least can some one please tell me the next steps to ending this nite mare. I need my bike desperately for everything. Thank u
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post #2 of 5 Old 04-14-2019, 06:17 PM
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Location: Maine
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whoa - how long have you had this bike and what work have you recently done before the problem?

1985 Rebel 250 ... 2005 Ruckus 50
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post #3 of 5 Old 04-14-2019, 07:12 PM
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I assume you checked for spark and the condition of the plugs. Curious as to whether you have installed an inline fuel filter, because on my first Rebel, I was having the same problem. Turned out to be a dirty carb. In hind sight, it didn't make a lot of sense that it would run on only one cylinder because of the carb, but that fixed it.

Keepin' all the left over parts. Gonna use 'em to build another bike!

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post #4 of 5 Old 04-14-2019, 07:18 PM
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First of all, nothing from a PCX will fit a Nighthawk. A PCX is a plastic CVT scooter with EFI. It's all computer controlled, so the wiring harness is completely different. The problem on your '93 is most likely fairly simple, since it has no computer parts. However, voltage takes a long convoluted route to the spark plugs. This may not be in the right order. I suggest you get a wiring diagram. It goes from the battery to the ignition switch, then through the emergency cutoff switch, through a clutch safety switch, possibly through a sidestand safety switch, then to the CDI, the coil, and finally to the spark plugs. The CDI replaces the simple points, condenser, and mechanical advance system in older models, but it does the same thing with no moving parts. Because there are no points, there has to be a Hall Effect sensor somewhere to tell the CDI when to send voltage to the coil to fire the spark plugs. The problem could be an open circuit somewhere in all that, I would start backtracking until you find voltage. The ignition switch has to be on and the battery has to be fully charged. I have seen so many different designs I don't know exactly what you have. I have never worked on the electrical system of a Nighthawk.
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post #5 of 5 Old 04-15-2019, 08:59 AM
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1) check the "Nanny" wire, GRN/WHT goes from the CDI to the sidestand switch and to the neutral switch.
this wire has to be connected to ground for the CDI to allow a spark, buy either the sidestand being up, or the transmission being in N, either one provides the needed ground.
2) check the kill wire, BLK/WHT, from the CDI to the run/stop and the key off, STOP or OFF connects this to ground and stops the CDI from firing the spark.
3) then doublecheck for a spark and clogged carb. My '09 rebel 'acted' like only one side was firing and then only with full throttle to get a pathetic choking almost running, and it turned out to be a dirty carb. that's why I said "acted", its behavior was very misleading.....

2009 Honda Rebel 250; 2009 Honda Shadow 750 Spirit
"The bravest thing for me to do is admit when I am wrong" - unknown
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