Coil issue??
 

I was riding my bike home today and my bike cut down to one cylinder like you cut off a switch. I got home and started trying to figure out what cylinder was missing so i pulled the front plug wire first. It would barely run on the rear cylinder and cut off after a few seconds. I replaced the plug wire and moved on to the rear cylinder. Bike runs fine on the front cylinder. idled and reved as well as you could expect from a single cylinder. With rear spark plug removed i can hear an arcing sound from somewhere between the rear cyl and the coil but could not see a break or crack in the plug wire and never could see signs of arcing on the frame. Is this normal? i couldnt hear such a sound from the other coil when i had that plug wire off. All of my tools at work so gonna have to borrow a meter and some tools from my dad tomorrow to get the tank off and ohm out the coil. so i guess my best bet would be to swap the coils around and see if the problem moves to the front cylinder?

ok found a meter. Im getting .6 and .7 ohms across the rear coil.

Check the wire connections at the coils. You can swap coils to see if it's a bad coil or another issue. Filling the tank all the way up and getting vacuum lock will give the same indications (cylinder cutting out). Make sure that's not the case.

.6/.7 for primary or secondary coil?

you have to bear in mind that there are 2 sets of coils in each individual coil.

If you've got the front side of the coil (input side from the ecu), check from the inside of the spark plug cap to ground with the run switch set to "on".

If there's wonky resistance or none at all, then you've found your problem.

the PDF up here for the serv. manual is a great help and covers this section very well.

If you need a coil, I've got one with hacked leads, but it's easily fixed with a little solder, shrink tube and tape =)

ok getting around 18k from the front side of both coils and from what ive read the rear side resistance is normal too. Maybe carb trouble? bike is completely stock with 8k miles i dont know that they have ever been cleaned but seems kinda odd that that cylinder would just cut out that abruptly after running so great for the last year that i have owned the bike. its not vacuum locked half tank and it still had the miss after it sat for several hours and i opened the gas cap. ive never had the carbs off of this bike but hopefully it wont be too much trouble to clean them up and check the vacume lines for leaks. what is the procedure for checking the vacume lines for small holes? on old trucks i always sprayed carb cleaner around the lines and found the hole when the engine revved. I would assume its different on a bike though.

#1 Rule of Ignition Problems - "If you think it's the coil, it's not the coil"

You say that you replaced the front plug wire, how about the rear? That sounds like the culprit to me.

Pull the spark plugs and see if the rear is fouled. If so then clean it off and check the gap. Install new plugs if necessary. Then see if the problem reoccurs.

Jamie, you're ohh so right, hahaha; found that out the hard way on my Hawk. But you never know! Better to check and rightfully remove it from the list of problems then move to the most complicated one =)

Make sure to check the switches, I was pointed in the same direction when I was having ignition problems. Start with kill switch, then side, then neutral (or at least that's my logical progression).

In fact, the service manual has a very good section of diagnosing no-ignition. Unfortunately, I got to the end of the list and no joy. That left me with a major ding =(

You can find the service PDF here

Hope your hawk feels better, dude.

i would take the plugs out but cant seem to find an 18mm that will fit in the hole. no tool kit on the bike. i bought a cheap 18mm socket at auto zone and ill turn it down on the lathe at work tomorrow so it will fit.

Craftsman makes a thin walled deep 18mm that will work without modification. ;)