Is it Spark or is it Fuel?

Hello all.
I picked up a really beautiful, relatively unmolested KZ1100 Spectre for a very small price. Of course it had been sitting up and of course the carbs were dirty.

The pipes look like the cheaper Mac four into one available on Ebay, and the vacuum setup has been disabled from the petcock on back. The coils are stock but the wires and boots have been replaced and they all test good according to the Clymers.

After pulling the carbs off the rack and putting them through the ultrasonic, I got a pretty darn nice runner, although quite loud with the pipes. It pops a LOT on decel. If it is revved high and released, fire comes out the pipes. Yet it's running the stock air filter.

After the first good long run, it developed a tendency to foul the #3 plug. I can pull it and clean it and it runs great, until it is revved high again. Not one drop of fuel has reached these carbs without being through a good filter...and the bike runs like a champ on all four if the throttle is used...judiciously.

I'm not a tuner, I just know how to clean up the carbs. I didn't see where these carbs had been re-jetted, but who would bother, and then run a stock air cleaner?
What's causing 1) the popping and 2) the plug fouling? a

I'm just trying to make a reliable KZ here, given the oddball exhaust. Thanks!

coffee_brake wrote: Hello all.
I picked up a really beautiful, relatively unmolested KZ1100 Spectre for a very small price. Of course it had been sitting up and of course the carbs were dirty.

The pipes look like the cheaper Mac four into one available on Ebay, and the vacuum setup has been disabled from the petcock on back. The coils are stock but the wires and boots have been replaced and they all test good according to the Clymers.

After pulling the carbs off the rack and putting them through the ultrasonic, I got a pretty darn nice runner, although quite loud with the pipes. It pops a LOT on decel. If it is revved high and released, fire comes out the pipes. Yet it's running the stock air filter.

After the first good long run, it developed a tendency to foul the #3 plug. I can pull it and clean it and it runs great, until it is revved high again. Not one drop of fuel has reached these carbs without being through a good filter...and the bike runs like a champ on all four if the throttle is used...judiciously.

I'm not a tuner, I just know how to clean up the carbs. I didn't see where these carbs had been re-jetted, but who would bother, and then run a stock air cleaner?
What's causing 1) the popping and 2) the plug fouling? a

I'm just trying to make a reliable KZ here, given the oddball exhaust. Thanks!

Hello, coffee_brake, and WELCOME to KZr!

Given perfect as-new carbs and popping on deceleration, would guess that at least one carb pilot circuit is too lean.
Reading the plugs may indicate a likely suspect.

Could start experimenting by enrichening only one carb's pilot mixture, say 1/2 turn counter-clockwise on the pilot adjustment screw. And test run. If popping is the same, repeat this on the next carb, and so on until the popping stops. Then leave the last adjusted carb alone, and re-set the other carbs to the original screw positions.

#3 carb is probably the least likely to need enrichening of the pilot mixture. But there may be other non-carb related reasons causing the #3 plug fouling.

If not already done, would assure valve clearances are within specs, and perform the clear-tube test on the #3 carb to determine whether fuel level might be too high.

For a better service manual,
Click here > www.kawiworld.com/index.php?option=com_c...icle&id=77&Itemid=99

Good Fortune!

If the bike is very loud it's possible the previous owner removed the baffles from the exhaust system. I would install baffles and see if problem persists. Ed

Oooh, much better manual! Thanks! The Clymer is about worthless.

This is the D2 model so it's kind of an oddball.
I'm trying to wrap my head around Patton's advice.
Please remember that I only know how to make the carbs be as they were stock. I'm not a tuner, I just put it back the way it was before, but clean with new rubber bits.

The pilot screws were 2.5 turns out, so I put them back that way. And you're saying it's getting too LITTLE fuel? I thought the popping and the fire coming out the pipes were signs of having too MUCH fuel in the combustion chambers.

OK so you're saying to just pick a carb and turn its pilot screw out a half turn?
Why not turn them all?

If #3 is least likely to be rich (remember there's no vacuum, it's a gravity feed system), why is it black and covered in carbon?

I'm happy to follow instructions and very grateful for the help, just trying to understand the causes of the problem.

Otherwise the bike is really fun to ride, although the big tall bars and cruiser seat don't suit me. It handles a whole lot better than I thought it would too, really nimble around town, for a cruiser. The big engine feels a lot like my '99 Bandit: powerful, smooth, and confidence-inspiring.

Oh, valves: I haven't adjusted them and doubt the previous owner did either. He kept it shiny and changed the oil every year, but nothing else was maintained properly. I've always had the nut-and-screw type adjusters, this shim thing is going to be a new challenge for me. Anybody got sources on shims, or advice on the valve adjust process? At 21k miles, I'm assuming that it will need adjustment.

650ed wrote: If the bike is very loud it's possible the previous owner removed the baffles from the exhaust system. I would install baffles and see if problem persists. Ed

Ed I'm not sure there ever were baffles in these pipes. I sure wish I had stock pipes on it, I'm not into noisy bikes.

coffee_brake wrote: Oooh, much better manual! Thanks! The Clymer is about worthless.

This is the D2 model so it's kind of an oddball.
I'm trying to wrap my head around Patton's advice.
Please remember that I only know how to make the carbs be as they were stock. I'm not a tuner, I just put it back the way it was before, but clean with new rubber bits.

The pilot screws were 2.5 turns out, so I put them back that way. And you're saying it's getting too LITTLE fuel? I thought the popping and the fire coming out the pipes were signs of having too MUCH fuel in the combustion chambers.

OK so you're saying to just pick a carb and turn its pilot screw out a half turn?
Why not turn them all?

If #3 is least likely to be rich (remember there's no vacuum, it's a gravity feed system), why is it black and covered in carbon?

I'm happy to follow instructions and very grateful for the help, just trying to understand the causes of the problem.

Otherwise the bike is really fun to ride, although the big tall bars and cruiser seat don't suit me. It handles a whole lot better than I thought it would too, really nimble around town, for a cruiser. The big engine feels a lot like my '99 Bandit: powerful, smooth, and confidence-inspiring.

Oh, valves: I haven't adjusted them and doubt the previous owner did either. He kept it shiny and changed the oil every year, but nothing else was maintained properly. I've always had the nut-and-screw type adjusters, this shim thing is going to be a new challenge for me. Anybody got sources on shims, or advice on the valve adjust process? At 21k miles, I'm assuming that it will need adjustment.

Too lean may cause the popping on decel -- is correct.

Why not turn them all? -- some may be okay as is.
Plug reading may help select most likely carb to first enrichen (as suggested).

Carb on running engine does produce vacuum.

Gravity feed system is a design feature, which doesn't cause sooty plugs.

If #3 is least likely to be rich -- indicates a mis-reading.
Would review the part that says, #3 carb is probably the least likely to need enrichening of the pilot mixture.

Sooty plug results from incomplete combustion (for whatever reason) and is often not carb-related.
A perfect fuel mixture only means that the fuel mixture isn't causing the sooty plug.
It's important to understand that any of several NON-carb-related issues can cause a sooty plug.
That's why it's important to assure all the other components are up to snuff.

Need:
• adequate compression at operating temp -- assure valve clearances within specs.
• fat blue sparks on plugs -- remove and visually observe.
• correct plugs -- NGKB8ES (the newer, the better)
• fuel levels within specs -- perform clear tube test.
• ZERO air leaks -- plug unused vacuum nipples.
• correct pilot circuit mixtures

In addition to the above, would also view operation of the ignition timing advancer under a strobe-type timing light, to assure that the advancer is functioning correctly. The weight arm pivots may require lubing, and maybe both cleaning and lubing.

Good Fortune!

Regarding possible air leaks, is the stock clean air system still fitted?
If so, it is fraught with possible air leak sources.

If removed, the breather caps in the cam cover should be plugged or connected to each other.

Another possible air leak source is the vacuum tube from carb or carb holder to the petcock. The tube may be split or cracked or leaking at one or both ends where it attaches to the carb nipple and to the petcock nipple.

And the time-honored leaking carb holders, that crack with age, and allow outside air to be ingested into the fuel mixture, which leans the mixture, which may result in exhaust popping on decel and/or a racing idle.

Good Fortune!

Lots of new information, thank you.

I'll start with the cheap/easy stuff first.
I will pull the (new) plugs and see what they look like. I got resistor type plugs because the new plug wires and caps are NOT resistor type. I didn't put the new wires and caps on there. Resistance is correct according to the manual.

All four vacuum ports in all four carbs have been plugged, but I didn't plug them. I think they may be letting in air. It will be a simple matter to make new plugs that fit better.

The stock air box and air filter are in good shape, and I put on new boots. The carb holders looked good but I did seal them to the engine very well with RTV to ensure they wouldn't leak.

I have no idea if the breather caps in the cover have been plugged. Didn't even know they were there.

What ARE the base settings for the pilot screws? 2.5?

From here I can go on to the clear tube thing, compression test, and then valves.

I do suspect the coils, because there is certainly a reason why the wires and caps (the cheap stuff) were replaced and yet the bike remained parked. But it idles great and rides just fine under smaller throttle inputs. In fact, it only fouls #3 when it is revved fairly high, higher than I normally ever need on a bike.

Thanks again for the information, I'm learning as I go...

coffee_brake wrote: Lots of new information, thank you.

I'll start with the cheap/easy stuff first.
I will pull the (new) plugs and see what they look like. I got resistor type plugs because the new plug wires and caps are NOT resistor type. I didn't put the new wires and caps on there. Resistance is correct according to the manual.

All four vacuum ports in all four carbs have been plugged, but I didn't plug them. I think they may be letting in air. It will be a simple matter to make new plugs that fit better.

The stock air box and air filter are in good shape, and I put on new boots. The carb holders looked good but I did seal them to the engine very well with RTV to ensure they wouldn't leak.

I have no idea if the breather caps in the cover have been plugged. Didn't even know they were there.

What ARE the base settings for the pilot screws? 2.5?

From here I can go on to the clear tube thing, compression test, and then valves.

I do suspect the coils, because there is certainly a reason why the wires and caps (the cheap stuff) were replaced and yet the bike remained parked. But it idles great and rides just fine under smaller throttle inputs. In fact, it only fouls #3 when it is revved fairly high, higher than I normally ever need on a bike.

Thanks again for the information, I'm learning as I go...

Resistor type spark plugs should not be used with resistor caps.
The resistance being to spec is appropriate for using with non-resistsor plugs.
Using both resistor caps and resistor plugs weakens the spark, causing incomplete combustion (and sooty plugs), even if carbs, fuel levels, compression, valve clearances, coils, and everything else, are all perfect.

The sealer may temporarily prevent carb holder leaks, but it's usually a short-lived repair. There are separate testing techniques to determine the existence and location of air leaks.

While 2.5 turns out from lightly seated sounds about right for the pilot screws, would refer to the downloaded FSM which will likely provide the default setting.

The FSM also says as to tuning, that a clean air filter, new spark plugs, and valve clearances to spec, are the minimum prerequisites before addressing the carbs.

All of the other previously mentioned items also affect carb performance. And even a perfect carb cannot compensate for deficiencies in the other components (compression, spark, etc.)

Acceptable combustion in #2 is an indication that #3's incomplete combustion (sooty plug) isn't due to a defective coil, because the same coil provides the same high intensity voltage to both #2 and #3 spark plugs.

Good Fortune!

I agree. If spark was to blame from a bad coil, then #2 would foul as well as #3. That's why I find myself asking, because the wires and caps are new.

Please note that I said the plug caps are NOT resistor type. Hence the resistor-type plugs. Oddly enough, when I asked for the correct plugs for this bike, the auto parts store dude looked up the bike and found two kinds of plugs: one type resistor, and one type not. Without resistors in the caps and straight copper wires, I thought it best to get the resistor type plugs.

Also, when testing the plugs, they all looked fat enough and blue enough to me.

But, isn't there a high-speed winding in the coil?

I'm days away from getting at the correct shims, IF the valves are out. Do most folks buy them new, or is there a set of shims circulating?

Fat blue spark indicates a good coil, but doesn't guarantee that the coil won't short when stressed and heated under load or fail if cracked and dampness gets through.

If in doubt, the Kawasaki dealer should have a Kawasaki coil tester, and would likely test the coil without charge.

But most owners probably see healthy fat blue sparks, and proceed as if the coil is just fine, unless and until actual ride-testing proves otherwise.

high-speed winding in the coil? -- perhaps referring to the secondary winding through which the high intensity voltage is produced upon collapse of a magnetic field (and all that stuff), so it's time for some homework and studying the manual, which covers the coil theory and function, along with loads of other good information.

As and when replacement shims are required to attain valve clearances within spec, would recommend checking with Z1 Enterprises.

Good Fortune!

coffee_brake wrote: I agree. If spark was to blame from a bad coil, then #2 would foul as well as #3. That's why I find myself asking, because the wires and caps are new.

Please note that I said the plug caps are NOT resistor type. Hence the resistor-type plugs. Oddly enough, when I asked for the correct plugs for this bike, the auto parts store dude looked up the bike and found two kinds of plugs: one type resistor, and one type not. Without resistors in the caps and straight copper wires, I thought it best to get the resistor type plugs.

Also, when testing the plugs, they all looked fat enough and blue enough to me.

But, isn't there a high-speed winding in the coil?

I'm days away from getting at the correct shims, IF the valves are out. Do most folks buy them new, or is there a set of shims circulating?

My local yamaha dealer exchanges shims with a two dollar charge per shim. After swapping shims around from valve to valve I only needed to replace 2 of them.