TOPIC:

Something happened to my bike this morning, and I’m not really sure what. When I left my apartment to go to work, all felt fine. I have to go through a few miles of stoplights before I get on the highway. I'm about half way to the highway, waiting at a red, when it finally turns green. I give it the normal amount of gas, and let the clutch go at the normal rate, and the bike dies! How embarrassing, me thinks. But this not being the first time in my life that has happened, I just pull the clutch back in and thumb the starter, and expect to go on my merry little way. But the moment I hit the magic button, I knew something was wrong. It took about 4 times as many cranks as normal to get started, and was running very rough, barely keeping an idle. But I think, 'maybe it just needs to work something out of its system'. SO I push on, all the way to the highway. As I start trying to accelerate, its clear something is really wrong. Geo's are passing me in frustration. I have it WFO, and my top speed is about 40mph. So I abort, get off at the first exit, and limp it home. At every stop it doesn’t want to idle. I have to give it about 3 times as much gas and be very gentle with the clutch or it stalls. It's definitely missing on at least one cylinder. And it all happened out of the blue with no warning.

CLIFNOTES: Bike is way down on power. One or more cylinders are missing. No warning.

Ideas?

might've lost a coil, pickup, or igniter. check for spark against the cylinder head.

Forgot to feed hamsters?

mine used to do that when it would foul a plug no warning just drop a cylinder after a rejet it ran great

Having ridden four cylinder bikes firing on 3 cylinders, they WILL keep up with traffic. FIRST thing to do is figure out which cylinders are not firing. Get a spray bottle and once the bike is warmed, and when the symptoms recur, spray the pipes a bit. The firing cylinders will vaporize the spray. The non-firing pipes will be hot from promimity but not as hot and the spray will just roll down the pipe and puddle. Once you have figured out which cylinder(s) are not firing, the course of action will present itself. The problem will be either compression, electrical or carburetor related. Until you have done a minimal amount of checking, the potential answers will be so vague as to be time wasters.

CRIFNOTE VERSION: Check pipes to see which cylinders are firing

While at work today, I got to thinking about how dirty my air filters are. I managed to convince myself this was causing my problem. So when I got home I pulled them off to clean them, and while they were off I went for a short ride. This didn’t solve anything. But on the plus side I was able to deduce a few things. 1. The problem is there cold as well as hot, so valve trickery seems less likely. 2. Because it was warmed up I tried george's trick -

wiredgeorge wrote:

CRIFNOTE VERSION: Check pipes to see which cylinders are firing

That's an awesome trick. This is my first multi-cylinder bike, I wouldn’t have thought of that.

And with that method, it was pretty clear I've dropped both of the inside cylinders. These bikes have two coils, right? By chance one coil doesn’t fire the two inside cylinders, does it? Can the coils be accessed without removing the gas tank, to check for loose connections?

The bike is cooling down now, then I'll go pull the two spark plugs out and see if they throw any light on the situation.

I’ve managed to wrangle some time off of work, next week. I was planning on taking my new bike a on a little tour around northern CA/NV to show it off to friends/family I have up there. I could take the KLR if this isn’t solved, but they’ve already seen it.

One coil operates the two inner cylinders on my kz650, and I wouldn't be surprised if it was the same on yours. Good luck, I hope you get it running like a champ again! Hope this helps! Also... It is necessary to remove the tank but it's the easiest thing on the bike to r&r.

Post edited by: 77kz700?, at: 2006/05/31 23:01

Alright, I took the tank off and looked around. How the ignition system works on this bike is now much more clear. I also pulled all the spark plugs. The two inner spark plugs were a very different color than the two outer plugs. Sorry I can be specific about the color, because I was doing thins under the yellow tungsten lights in a parking lot across from my apartment. We’re not allowed to work on bikes/cars in our own parking area. I was also about 80% sure I found a loose wire to the left coil. After fixing that and putting the outside plugs back in the inside cylinders, and vice-versa, I thought for sure I had this licked. But a test ride proved me wrong.

At this point I feel pretty confident the left coil is toast. Am I jumping to conclusions? Should I replace both coils at the same time? Is there an obvious aftermarket upgrade I should use instead of OEM equivalent stuff? Where’s the best place to buy parts for an old bike like this?

You guys are GREAT!

i don't think that i would jump to buying anything unless you know it is going to cure it. why waste money.

i would be sure that the coils are firing. go to like walmart or kmart and buy a small spark tester (most are the size of a spark plug) be sure about the firing. remove one wire at a time. test and then go from there.

say two and four are not firing, then it could be more than just coils. also be sure that you have good power to the coils. check your grounds.

if you could, take a pic of the plugs and post it on here. all this can be done really with out even taking the tank all the way off. this way you might not get into trouble with your apartment complex.

it really sounds like to me that a wire came loose or some thing like that.

good luck.!!!!!!

OK let think here... Both cylenders 2 and 3 fire 180 degrees apart ant operate off of the same coil...right. I would recomend checking the coil off of the bike for spark strenght and resistance should be 3 ohms across the coil? not sure off the top of my head. anyway does your bike sit outside? there are more connections that go to the coil than the ones right there. Don't give up! you're smarter than the motorcycle. Also about the plugs. If you have weak spark a plug can get fouled within only a few miles of riding. check agian I think your close.

absolutepat wrote:

And with that method, it was pretty clear I've dropped both of the inside cylinders. These bikes have two coils, right? By chance one coil doesn’t fire the two inside cylinders, does it?

Usually the outside cylinders (1 + 4 ) are powered by the left coil and the inner two (2+3) are powered by the right coil. Unless someone switched the coil positions, of course.

Do you have a multimeter and a manual? The first check should be looking for obvious loose, broken, shorted wires. Then check the wires to the coil and see if you are getting any voltage to the suspect coil.

Post edited by: OKC_Kent, at: 2006/06/01 10:07

If 2 & 3 are non-firing, this suggests an electrical issue. The problem may or may not be the coil. Before jumping to any conclusions, test to see if the problem IS the coil or another part of the ignition system. It is pretty easy to test...

Step 1. There are two small wires that connect the coil to the ignition and power source. One of these wires will be the same color on each coil. One of the wires should be red or yellow/red. This is VOLTAGE to power the coil. First thing to do is to check the voltage to see if the coil is powered. Get a multimeter. Put it on VDC scale. Turn the key on. Put the HOT multimeter lead (POS/RED) in the connector of the wire where it plugs into the coil. The multimeter ground lead (NEG/BLACK) should be held on a frame ground. You should get about 12.5 VDC with the key on and the bike not running. If you get less than 12.5 VDC, you will also get poor spark but anything over 10 VDC, you should get SOME spark. If you get ZERO (0) VDC, then you have no power going to the coil. The course of action needed will depend on the voltage reading... If you get about 12.5 VDC, then go to step 2. If not, let me know!

Step 2. Take the OTHER wire connected to the 2/3 coil which should be green and remove it from the coil. Go the 1/4 coil and note that a BLACK wire is connected to it. Swap the GREEN wire to where the BLACK wire was and put the BLACK wire where the GREEN wire was.

Once you have done this, move the 1/4 spark plug wires to where and the 2/3 wires were and vise-versa...

What you have done is made the 1/4 coil the 2/3 coil and the 2/3 coil the 1/4 coil. Now start the bike... IF the problem now moves to the outside cylinders, you can assume coil (the original 2/3 and now the 1/4) is toast. If the problem remains on the inside cylinders (they are not firing), you can assume some OTHER ignition component is toast or not connected. If you find a bad coil, buy a new set of coils and if you find that the problem is elsewhere, more troubleshooting is required.

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When you break down troubleshooting in logical steps, you will find the problem quicker and spend less money buying stuff that is not needed. In addition, you won't muck up things that happen to be working correctly by mis-adjusting them. Always, only make ONE change to the bike at a time and test the effect of the change rather than adjust your ignition, adjust your carbs, adjust your valves, and then check. If the initial problem is fixed, you will likely have a new problem caused by the multiple changes made. Let us know what you find with the coil checking exercise. The problem MAY OR MAY NOT be with the coil involved but it is easy enough to check as detailed above!