Honda CB Not getting a spark at the sparkplugs

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fozzy_gump

New Member
A buddy and I are troubleshooting the bike and were both kind of stumped. The root of the problem is that none of the spark plugs are firing. I imagine it has something to do with the electrical system farther up the line, but I'm not sure where to start. We've been messing around with a voltimeter trying to figure this thing out. Any tips or pointers?
 
you can do a bench test on the coils.

start by installing a known good spark plug into plug boot of suspect coil.

wrap a wire around the threads of spark plug and the battery - (neg).

hook coil + wire to battery + lug (positive)

Momentarily "TOUCH" coil - (neg) wire to battery - (neg) for just a second

when you remove the coil - (neg) wire from the battery - neg. you should see a spark at the spark plug.

If you leave the coils + and - hooked to battery too long, coil will get hot and could fry it. So just "TOUCH" the negative wire to the battery.

You can also check the coils strength by opening up the gap on the plug. A bunch.

If it sparks. you can add the condenser into the mix as per your wiring diagram. and run the same test again.
 
Thanks. I'll try that. Do you know, can you detach leads from the coil to replace the leads and the plug boots? After looking around I'm almost certain the plug boots are bad after so many years and are falling apart. I'm afraid they're built in though which would mean I'd have to replace the coil regardless.


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http://www.carlsalter.com/honda-service-manuals.asp

I dont know anything about your bike other than its a CB. The stock boots unscrew off the leads of stock coils on a 1976 CB360.
 
Sorry it's a 73 cb500. I'm out working on it again today. I haven't gotten around to bench testing the coils themselves to see if I get a spark yet and I don't know if I will. I'd have to cut the wiring and splice it back together which I don't want to do just yet. I'm pretty certain it's the leads themselves that are faulty though.

9f1d37c432079962765e99bfd815776f.jpg


When I test the coils themselves I get a reading, but when I stick the negative end inside the lead where the spark plug boot connects I get no reading.

62462e815f75d55041ed46a9c3c70eb8.jpg


Is my logic sound here? I figure if I replace the leads I should get a reading all the way from the coil down to the spark plug boot.


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Sorry I posted the wrong picture. Here is the pic when I test the coil and the leads together.

f42edce17fa7338c05fdf3c34290a758.jpg



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I got a good 6v coil sitting here. From 72 CL100.
It reads 1.8 ohms pos to neg leads.
pos to plug wire is 10.4 k ohms
neg to plug wire is 10.4 k ohms

Dont know if that helps really, but its a result.

Not pulling 12v 360 coils apart to check them. sorry. but they are on the bike.
 
No that's a huge help. I wasn't sure if I was supposed to get a reading all the way through to the plug wire. Looks like something is wrong within the leads or the plug boots. I'm really new to all of this and didn't know what half of these words were a few days ago. Thanks for the help. I'll try to remember to update you if this ends up being the (only) reason I'm not getting a spark at the plugs.


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Finally got the plugs to spark! It was just bad wire inside the leads. I snipped them back and got a small spark. I'll probably replace them regardless, but I am getting a spark now


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