KZ440 D4 LTD Engine Woes

Having trouble getting my KZ440 to fire. Both cylinders have 120+ compression, battery voltage reads within acceptable parameters, new spark plugs that are firing, stock chopped pipes right behind the heat exchanger with 4" baffles and shorty mufflers. Valves have been checked and adjusted, all electrical contacts have been cleaned and filed, and the carb has been blasted to hell and back (Installed an original airbox to replace pods and went to a 92 on the main jet to account for the pipes being chopped). Stock Keihan CV carbs with a brand new gravity fed petcock and the vaccum port on the right carb is capped. The bike will turn over and the starter is working but I can't get it to fire for the life of me. Float bowls are filling up and lines aren't clogged. Spark plugs don't seem fouled when I check them after trying to fire; they smell subtely of gas but don't have anything on them and aren't discolored.

The bike ran fine then sat for three months; the only changes made were the gauges got stripped, the pipes were cut and the engine cases were polished. Filled it up with oil and ran into this issue. The bike will backfire out of the carbs but I'm yet to get the engine going. It's got a timing advancer that is assembled properly (Not flipped like a dumbass) but It sounds like a timing issue to me.

I have it at a mechanic right now who thought it was a quick easy carb issue but I can't afford him to diagnose whatever the heck is going on now that he's decided it isn't, so I'm going to diving back in. I'll be posting a video after the holiday when I pick it back up so you guys can see the symptoms.

Any ideas gents?

EDIT: I've dumped and tried new gas many times. Literally have taken the carb apart completely three times and the mechanic that has it did a sonic cleaning on it and reassembled with the same problem. The only thing I havent done (And I'm not sure if the mechanic did) was unplug the pilot screw and adjust it (It's covered by a cap). Could that be contributing?

Cases polished? What did you take apart?

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Am thinking the carbs' pilot screws should have been uncapped and removed incident to cleaning, because it's important to assure unobstructed orifices through which the pilot mixture enters the bore.

What's a heat exchanger?

Good Fortune!

Did check that the coil's are wired to the right pickup's and didn't get swapped ?

Sorry, meant covers, not cases... That'd be a hell of a different story. I've previously replaced the clutch plates and rings and I took off the stator cover, clutch cover and front pulley cover. I'm pretty green at all this but everything worked great until it sat.

By heat exchanger I meant the small pipe that connects the 2-2 exhaust together under the engine, old mufflers were rusted and full of holes. I chopped them about an inch past that pipe and installed 4" baffles and some cheap-o short mufflers. I thought backflow was the issue at first but everyone I've talked to said it's something else.

I haven't checked the cables to the coils, I was thinking of that while writing this; I read in a thread on here that it doesn't matter on this bike and you can swap them without issue but that didn't make sense to me. I'd hope to god the mechanic would've thought of that but it'll be first thing to try when I pick it up. I also got a cheap coil off craigslist to swap if that doesn't work to rule out a coil issue.

I didn't know the pilot adjust screw existed when I was cleaning the carbs, I'm learning slowly as I go. Once again, I'm hoping the mechanic would've unplugged them and blown it out. I definitely blew out that passage during my two run throughs and made sure it was unobstructed, I just didn't uncap the outside screw side.

Hah, it was actually Patton that said it: "Dual wire coil fires both sparkplugs simultaneously, so it doesn't really matter which plug wire goes to which plug." That applies to my KZ, correct?

Well said! :lol:

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These illustrations may help understand "firing" through the "secondary loop."







When viewing spark quality with plugs removed and held grounded against the engine head while spinning over the engine, must watch very closely to see which way each spark jumps across the tip. :lol: :lol: :lol:
I don't know of anybody other than Old Man Rock and loudhvx, and maybe bountyhunter, that are actually able to do this.

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If there's a break anywhere in the secondary loop, neither spark plug will fire.

A break may be anywhere, such as:
• Inside the ignition coil (broken or shorted wire in the secondary winding;
• Poor connection of a plug wire to the coil tower;
• Plug wire that's broken inside or shorting through the insulation;
• Poor connection of a plug wire to the cap;
• Defective plug cap;
• Poor connection of cap to plug;
• Bad spark plug.

If one plug is firing while the other plug isn't firing, current may be passing through the non-firing plug, or voltage could be by-passing the non-firing plug through a plug wire that's shorting to the engine head.






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About the dreaded "Wasted Spark."

The "wasted spark system" means that when both plugs fire simultaneously, one of them is doing its expected job of igniting combustion inside a cylinder filled with compressed fuel mixture. But the other simultaneously "firing" plug is wasting its spark during the other cylinder's exhaust stroke.

While both pistons rise and fall together, they are 360° apart in their respective four stroke cycles of Intake - Compression - Power - Exhaust.

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Dampness may sometimes impair functioning of the secondary loop, and result in degraded spark quality (or no spark).

High intensity voltage may leak through old hard cracked worn out spark plug wires, and short to the engine head.
Dampness worsens the problem by facilitating the leakage.

One method to test condition of the plug wires is by spraying water mist over the plug wires with engine running in a dark garage (or outside at night in an unlit area). An impromptu fireworks show indicates leakage of high intensity voltage through the plug wires shorting to the engine head. A somewhat entertaining, but less than desirable test result. :lol:

When high intensity voltage is leaking, the rider may sometimes feel an electrical "buzz" upon touching a metal part of the bike, such as for example when switching the petcock to reserve tank.

If an ignition coil is cracked, dampness may enter and short the wiring inside the coil.

The dampness issue with defective plug wires or cracked coil may become evident when the engine won't start running after the bike has been sitting outside in the rain, or in damp weather, or after riding in the rain, or after washing the bike.

When all components of the secondary loop are in good condition, dampness should not degrade spark quality.

Spark quality may be viewed with the plug removed and held grounded against the engine head while spinning over the engine. Look for fat blue sparks -- not wimpy orange sparks.

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Thanks for all the coil diagrams Patton, swapped it with a working one and nothing changed.

So the mechanic didn't have any luck in two months, I grabbed the bike to figure it out myself. He confirmed/did the following:

Leak down test, reported acceptable compression at under 20% loss.
Sonic cleaning on the carb. Pilot adjustment screws were uncapped, so I assume he cleaned them as well.
Tested the battery and cleaned all the contacts.
Verified valve setting, within acceptable margins.

I took off the timing cover and the engine rotates fine and the timing is correct.

When I got the bike back I swapped the coil to a different (used, but I saw it in use on a working bike) one I had picked up cheap.

The bike now just backfires through the carb and exhaust like crazy, still won't fire up. I backed out the pilot adjust screw one and quarter rotations and went all the way to two rotations in quarter increment steps, I'm going to play with it more when I get home today but I didn't notice any noticeable difference at all before the battery died.

Used new gas and made sure the bowls were drained and clean. I'll also take a video when I get home so you guys can see more clearly what it's doing. I'm so stumped it's ridiculous!