coil melted?

hey there, new member here, looking for some sage-like advice.

i have a '78 kz650 B2 that's been neglected in my parent's garage for a few years. my father bought the bike at 3,000 miles, after it had been sitting in the previous owner's basement for about 10 years. it kicked right over, but needed to be worked on some to get it rideable again. the local kaw dealer got it running again, and it rode great. my father sold the bike to me at 9,000-ish miles about 6 years ago. the bike's currently at 12,000 miles, although i haven't ridden it regularly for 4 years. this weekend i was getting it ready to move to my current home, about 100 miles away.

checked the tank and noticed a small bit of rust. charged the battery, but couldn't use the electric start. used the kickstart and got the bike running after a few minutes. the engine idled smooth right from the start.

about 40 miles into a ride with my father, the bike started to lose power - couldn't accelerate. then it started to backfire [which it had never previously done]. after about a minute of backfiring, the engine quit. just before the engine quit i noticed an acrid burning smell.

i was unable to get the bike to respond to kick starting, then i noticed that all the electrics were dead. no indicator lights, horn, starter...anything. looking under the tank, i noticed that the starboard coil had melted plastic down the front and some had fallen onto the top of the engine [the cam cover?].

- here's a good place to point out that i'm not well versed with engines. i can yank a computer apart and repair it again with my eyes closed, but never got into engines. i'm a quick learner, though, so please point out if i misname something or state false assumptions. -

so i assume that the coil need to be replaced, and i probably want to inspect the electrical wiring system as well. i never did check the fuse box, but also assume a fuse blew there, too. the bike is back at my parents garage, so i'll be limited to driving there weekends to work on the bike until it's rideable again so i can transport it here. this week i'm gathering info so i can attack the issues this weekend and order some parts. i have a clymer manual shipping to me, and have downloaded various docs from the kzr.com filebase.

i'll post photos when i get back to the bike, this weekend. so...any initial ideas? things i should look out for?

cheers!
-bt

Wow. Maybe I don't have enough experience with coils, but I didn't realize that they could melt, and drip slag on the engine.
Are your coils positioned really close to the top of your engine?

ltdrider wrote:

Are your coils positioned really close to the top of your engine?

i can't say that they are exceptionally close; they're tucked just under the tank, and a few inches over the engine, what i believe to be the cam cover [the top front of the engine.

this is the starboard coil, which has plugs 1/4 attached to it. from what i've read plugs 2/3 are supposed to be connected to this coil. i've never adjusted this myself, and don't recall my father changing it. i can only assume that's how it was returned from the shop when we first had the bike overhauled, years ago. does it matter which coil the 2/3 and 1/4 pairs are attached to?

-bt

One coil fires 1 & 4, and the other coil fires 2 & 3. The location of the coil (left or right) is not important. If the bike was running fine before you cooked the 2/3 coil, then your ignition and plug wires should have been fine. You may want to take the tank off, and look at the wires that feed the coils, just to check for signs of high heat.

Edit:
Here's a pic of the coil setup on my 900. These are aftermarket Dyna coils, but they are in approximately the same location as the stock ones. The farther they are from the cam cover, the better.

Post edited by: ltdrider, at: 2006/01/30 20:12

I wouldnt think the heat from the engine would melt a coil. You must have some charging issues. I burnt out a coil by having a bad regulator once, but before that I blew out most of the lights. Regardless you are going to need a coil, but once you get that and get running you will need to look at your charging. Check with a multimeter at the battery what voltage its getting charged at. Someone correct me if Im wrong, but if thats over 13.5-14 volts you have a bad regulator, or a short somewhere.

I really doubt anything else burnt your coil. It probably is bad by your description, but sometimes they can drip a little and not necessarilly be bad. If it's a 4" gob of plastic, that's bad for sure. If it's a 1/2" puddle of waxlike substance it may not be bad. By your description though it sounds like you may be right, sounds like you lost 2 cylinders first then possibly blew a fuse. I always have the thought that if it hasn't happened to me by now it is a very rare failure. My 78 B2 has 167,000 miles and still running the original coils. I've never had 1 coil failure on any of my Kawasakis in over 300,000 miles of riding them.

your experience certainly speaks to the endurance of these bikes!

my gut feeling is that something is wrong with the electrical system, that i never noticed, or went while the bike was dormant, and this coil is a result of that. maybe it's not even the coil but some other insulator melted and spilled down the front of the coil...but there was a lot of slag.

i'll know more when i take off the tank this weekend.

thanks for the feedback so far!
-bt

bt - A coil consists of wire windings covered in plastic insulation. The coils have considerable resistance and thus, can get quite warm. Placed under a gas tank, they don't really cool as well as they should and would be better served to be out in the airflow. In any case, the insulation on the windings gets hard and brittle with age and exposure to heat. When the insulation gives way, a short occurs. Initially this will show up as erratic plug firing and eventually failure. If you continue to operate the bike; probably on two cylinders (each coil fires two cylinders), the shorted coil will eventually fry and then melt. That is what occured in your case. When the short occured, a fuse eventually fried; probably the main fuse. It is likely that this fuse was rated higher amperage than what had been intended in this application as the fuse should have let go prior to total melt down. I doubt anything is wrong with the bike; just replace the coils, plug wires/caps and fuse and give it a shot. Dyna makes excellent coils which can be purchased reasonably at www.z1enterprises.com . When you connect the new coils, you will note that there is a power wire running to one lug on each coil. This wire will be either red or yellow/red. The other wire is the wire that comes from your ignition. On one side, the black wire connects to a lug and this is the 1/4 coil. The black wire is what makes it the 1/4 coil as the wire comes from the side of the ignition timed to fire the 1/4 plugs. The other (2/3) wire will be green and connected to the same lug on the adjacent coil. Make sure when you connect the new coils that the power wires in particular are not touching any metal except for on the coil... they are just metal screws retaining the wires and this is what I call "lugs".

Last tip... the EASIEST way to make a quick check of the bike's charging system would be to use a multimeter set to VDC scale (probably 20VDC). With the bike idling, put the POS (RED) probe on the battery POS terminal and the NEG probe (BLACK) on the battery NEG terminal. They should be marked with a plus and minus respectively. You should get about 12.5 - 13 VDC. Rev the engine to about 3.5K rpm and you should read under 16VDC. If the voltages are significantly above or below what I indicated, you have charging system problems which could lead to damage of electrical components. If they are within the bounds I noted, your coil that melted was just old and tired and waiting to die.

Post edited by: wiredgeorge, at: 2006/01/31 09:34

thank you...that's all great information. i'll order some coils as indicated and perform the tests you mention this weekend and see where we're at.

btw, is there any specific benefit to switching to an electrinic ignition system [such as the dyna-s system]?

cheers!
-bt

Definately if you want to use the bike switch over to electronic. The points are the reason most these bikes were given up on and sat around rotting. Darn things need constant fiddling with. Get electronic and you're set to go.
bionicTechnophobe wrote:

thank you...that's all great information. i'll order some coils as indicated and perform the tests you mention this weekend and see where we're at.

btw, is there any specific benefit to switching to an electrinic ignition system [such as the dyna-s system]?

cheers!
-bt

some good electrical advise. I just wanted to say that the stock location is fine for your coils, dont take the advise to move them away from your engine, as someone else said, the further you move them up, the more surrounded they will become and less air will flow around them. Its like shoving your stereo(or if youre a computer guy) picture it like pulling your power supply fan out and wrapping the power supply in socks, to shield it from the heat sinks on your motherboard.

The voltage limit top end should be able to safely climb to 16.5 in my humble experience... anyways... that was my 3.5 cents. You can make your own coils by the way, there isnt really much to them and get yourself a feeler gauge, a monkey can set points, and unless you need your bike every single day and cant spare ten minutes to check point gap, you dont need to spend a wad on electronic ignition, although, that said, its on my wishlist.... as it is everyones. I may have a spare set of coils you can have, I will know by the end of the week

xsc:

thanks for the power supply analogy...i understand completely.

i just bought another [non-running] '78 kz650 yesterday, and am having it delivered to my garage today. in the short term i might part it out for my kz.

in the long run, provided the causes of it not running aren't too severe i might get that one riding, too. so, let me know about your coils if it's not too much trouble.

cheers!
-bt