81 KZ550 - No Start

Reviving an 81 KZ550 with TK carbs, pods and 4-1 pipe. Bike sat for a year. Compression check is good 150-160 lbs. Cleaned the carbs and noted the main jet has been changed from a TK to a mikuni 112.5 and the needle jet is shimmed 2nd groove from the bottom. Mixture screws were set at 4.5 turns out(I think way too much)

Have a portable gas tank installed, vacuum port is plugged off, new battery and nice fat spark on all the plugs but she just won't start. Lots of gas in the float bowls. Any suggestions?

Will she light up with a shot of starting fluid? Are the wires in correct order? Smell gas on the plugs? If ya got spark and the timing is on the problem is narrowed to gas or air. Clean air filter and no obstructions narrows it to carb. Your portable gas tank is vented right?

Tried starter fluid, all it does is cause backfires. Checked spark plug wires and coil connections,fires 1&4 2&3, pod filters are clean. Plugs smell of gas but are not wet. Yes the tank is vented, I'm also thinking carb problems.

welcome to the world of munged up carbs it will be your pilot jets and circuits.clean them well with spray carb cleaner and use compressed air to blow out the passages.

If the starting fluid causes nothing but backfires it could be a timing issue. Have you recently adjusted the cam chain? I'd check my advancer too. Could very well be carbs but usually a shot of starting fluid will get her firing(not so much backfiring) a bit if everything else is ok. At least thats my experience.

Haven't touched the top end but will adjust the cam chain, and check the advancer but I'm leaning towards a carb problem.

gaillarry wrote:

...81 KZ550. Mixture screws were set at 4.5 turns out(I think way too much)...won't start. Lots of gas in the float bowls. Any suggestions?

Concur that pilot air screws are set way too lean (letting in far too much air). Would set them 1.5 turns out from lightly seated.

Enrichener circuit (choke) is designed to function with the throttle slides fully closed down. So do not even touch the throttle when starting a cold engine with the choke fully on.

Imo, the starting problem is not the main jet size and not the needle clip position.

Good Luck!

I've reset the mixture screws to 1.5 turns out. Can someone confirm the coil wiring for me. The left coil fires 1 & 4, has a green wire and a red/yellow wire. The right coil fires 2 & 3, has a black wire and a red/yellow wire. I have a wiring diagram but it's faded.

gaillarry wrote:

I've reset the mixture screws to 1.5 turns out. Can someone confirm the coil wiring for me. The left coil fires 1 & 4, has a green wire and a red/yellow wire. The right coil fires 2 & 3, has a black wire and a red/yellow wire. I have a wiring diagram but it's faded.

Thinking black wire should go to whichever coil is firing outside plugs #1/4. And green wire to other coil firing inside plugs #2/3.

Under the points cover, the left-hand module (or left-hand set of points) should have its wire (presumably black) routed to whichever coil fires #1/4. And the right-hand module (or right-hand set of points) should have its wire (presumably green) routed to whichever coil fires #2/3.

Good Luck!

G, A quick check shows wiring to be correct. However, your' symptoms are very similar to an instance I had with a a Martec ign which required only swapping wires to purr. I would try swapping grn and bk wires at coils just as a check, would only take a minute and could elimnate a possible cause. G

gaillarry wrote:

I've reset the mixture screws to 1.5 turns out. Can someone confirm the coil wiring for me. The left coil fires 1 & 4, has a green wire and a red/yellow wire. The right coil fires 2 & 3, has a black wire and a red/yellow wire. I have a wiring diagram but it's faded.

That's not the stock config. for the small KZ's. (The larger 900/1000/1100 bikes use left for 1&4, right for 2&3.)

On the 550's and 650's (and presumably the 750-4), the left or rear pickup (with small black and blue wires) controls the ignition for the 1&4 cylinders. This means through the ignitor, they fire the right coil which has a black wire to it.

The right or front pickup (with small yellow wire and red wire) controls the ignition for the 2&3 cylinders. This means through the ignitor, they fire the left coil which has a green wire to it.

The red/yellow wire goes to both coils.

When 1&4 are near top dead center, the pointer on the ignition rotor should be pointing to the left or rear pickup.

When 2&3 are near top dead center, the pointer on the ignition rotor should be pointing to the right or front pickup.

If the rotor is pointing the wrong way, someone may have rebuilt it backwards. You can easily fix that by removing the advancer and flipping the rotor 180 degrees.

It doesn't really matter which coil is mounted where, as long as the one with the black wire fires 1&4 and the one with the green wire fires 2&3. However, it would be less confusing if you can keep it in the stock configuration.

Here's some more info on the pickup magnets and rotor orientation.
kzrider.com/index.php?option=com_kunena&...d=4&id=134605#135713

Also, the TK22's don't use an enricher, they use an actual choke plate with spring-loaded flap. Sometimes you have to play with the throttle during startup until you getr the choke and fast-idle screw dialed in. To make it easier to dial in, you can try this mod after you get it running.

www.geocities.com/loudgpz/GPZchokeScrewMod.html

By the way, 112 seems way too big for a KZ550. I'd try a 96 or 98 depending on the exhaust and pods. Maybe a 102, but that may get sluggish in really hot weather.

Shimming the needle in the TK22 can lead to the needle rubbing on the needle jet opening. If you get some of the common rebuild kits, they will come with new jets and adjustable needles.

I posted a bunch of jetting info for the TK22 in this thread.
kzrider.com/index.php?option=com_kunena&...ew&catid=3&id=262010