1975 KZ900 Advance curve information

Just installed a Dynatek 2000 DDK2-1C electronic ignition on my 1975 KZ900 bike because ignition was always bad. Sparks plugs would get sooted up because of not enough spark. Thought I would go with this because it was progammable and it also got rid of the mechanical advance. I used advance curve 4 because it would bring all the advance of 40 degrees at 3500 RPM. Static timing was set at 40 degrees.
I also bought the progamming kit so I could play with it. After reading the Clymer book it was saying for this year that all advance should be in at 2350 RPM. I also opened the spark plug gap from .028 to .040 because the 1980 had a CDI ignition using the same plugs and would get more spark. The bike runs a lot better but I want to play with the advance.
SO the question is does anyone have the original information for what the advance is suppose to be. Something like the advance at idle is 15 degrees and max advance is 40 degress. Or is this all wrong. The bike is stock wtih 4-1 header and open air breathers.
Thanks, Guys.

If you are running stock coils than you are wasting your time. If you are running the Dyna green coils than the spark will be "real"

Per FSM for Z1~KZ900:

~Z1F-32818
5 deg @ 1500 to 40 deg @3000

Z1F-32818~
20 deg @ 1450 to 40 deg @2350

RPM is +/- 100 with straight line increase.

Good Fortune!

Would measure voltage at coil primary terminals to assure coils are receiving full battery voltage, or at least assure minimal lost voltage between battery and coils.

At idle rpm, voltage should be 12~13 VDC.
At 4000 rpm, voltage should be 14~15 VDC.

Good Fortune!

Regarding sooty plugs, if not already done, would perform compression test and assure valve clearances to spec.

And also perform clear tube test to assure fuel levels aren't too high.

And assure air filter is clean and unobstructed.

If using pods, some brands obstruct entrance to pilot air passage.

Good Fortune!

Thanks guys,
The motor serial number is Z1E 071916. The fork sticker says Z1F 72134. So that fits with your second entry 40 deg@2350. Do know what it is below 1450 RPM?
Curve 4 says
10 deg 0 rpm
15 deg 650-1000 rpm
Straight line to 37.5 deg at 2750rpm
Then another straight line to 40 deg at 3500 rpm
I'm reading these numbers off the graph they have provided.
What do you think?


The coils are Dyna DC4-1 2.2 ohms gray coils. I now get a snap when the plug fires. Before it was just this useless little blue spark which i had to look for in the dark.
Thanks.

blue75kz900 wrote:

Thanks guys,
The motor serial number is Z1E 071916. The fork sticker says Z1F 72134. So that fits with your second entry 40 deg@2350. Do know what it is below 1450 RPM?
Curve 4 says
10 deg 0 rpm
15 deg 650-1000 rpm
Straight line to 37.5 deg at 2750rpm
Then another straight line to 40 deg at 3500 rpm
I'm reading these numbers off the graph they have provided.
What do you think?


The coils are Dyna DC4-1 2.2 ohms gray coils. I now get a snap when the plug fires. Before it was just this useless little blue spark which i had to look for in the dark.
Thanks.

With the automatic advancer unit, the minimum advance is set at 20 degrees, regardless of very low rpm.

Am uncertain why lesser degrees advance would particularly matter between 0~650 rpm (or even between 650~1000 rpm).

Good Fortune!

I just did an engine top end overhaul because of compression and oil leaks. All is good now.
Overhauled the carburetors also, clear tube test was good for fuel level. Breather don't block the pilot air.
I did fix up some connections to the coil power and got it so that it was only .3 volt difference from the battery voltage. I will check again while its running but I think its OK.
I don't have sooty plugs after the first 30 min 15 mile run. Plugs were clean. I still have to dial the jet needle one knotch because I still think its a little rich. I couldn't do this before because it didn't have enough spark to run. Before this I would have completely black plugs after the same run.
I have a lot of carbon buildup already from the engine rebuild that i need to get rid of, any suggestions?


So how long do I need to let the bike warm up before I ride. I thinks it better now but i still need about 5 - 10 minutes in 75 degree weather before I can take off.

I haven't had a chance to synchronize the carburetors with the borrowed manometer yet. Mechanical sync it good.

Thanks.

blue75kz900 wrote:

...Overhauled the carburetors also, clear tube test was good for fuel level. Breather don't block the pilot air...coil power...only .3 volt difference from the battery voltage...don't have sooty plugs after the first 30 min 15 mile run. Plugs were clean. I still have to dial the jet needle one notch because I still think its a little rich...how long do I need to let the bike warm up before I ride...need about 5 - 10 minutes in 75 degree weather before I can take off....

Stock carbs??

Likely not a sync issue, imo.

5 - 10 minutes in 75 degree weather before able to ride is way too long.
1 minute should provide ample warm-up, with choke completely off after 15~30 seconds.
Likely too lean pilot circuits for whatever reason.
Would try turning pilot screws in clockwise to enrichen mixture, say 1/2 turn each, and test run.
If no difference, may have defective pilot screws (damaged ends) and/or blockage in pilot fuel passages.
Are carb vent lines clear and exiting to open air?

Would put jet needle clips in stock middle position.

Info from Z1E:
Z1 KZ900 Carb Identification & Specification

28mm (VM28SC) Z1 & early Z1-A
Main Jet 112.5
Air Jet 1.0
Needle Jet P-8
Jet Needle 5J9-3 - last number is the clip position where 1 is at the top of the needle (leanest) and 5 is at the bottom (richest)
Throttle valve (slide) 2.5mm cutaway
Pilot Jet 20.0
Air Screw setting 1 1/2 turns out

28mm (VM28SC) Late Z1-A & all Z1-B
Main Jet 112.5
Air Jet 1.0
Needle Jet O-8
Jet Needle 5J9-2 (last number is the clip position)
Throttle valve (slide) 1.5mm cutaway
Pilot Jet 17.5
Air Screw setting 1 1/4 turns out

Good Fortune!

Thanks for all the info, I will have to try more things.
Mine is setup like Z1-B (Z1-B is 1975-1976, right) except Jet needle is in slot 4 and I will be changing to 3. All new needles, pilot jets, needle and seat, jet is 113.
I tried turning out to 1 1/2 turns but idle ran too fast. The bike is also idling too fast right now. After its warms it runs 1000-1500.
Thanks time for bed.
Also pilot screws in 1/2 turn would make it leaner wouldn't it? That would only be 3/4 turn out from bottom. Vents are clear.

From everything I have read, the dyna-2000 is a 3 Ohm system and requires the green 3 Ohm coils. If this in fact is true than using the 2.2 Ohm gray coils will fry one or the other. The gray 2.2 Ohm Coils were intended only for OE Kawasaki ignitions starting in 1981.

blue75kz900 wrote:...pilot screws in 1/2 turn would make it leaner wouldn't it?....[/quote]

Nope --- may help to remember the pilot AIR screw allows more air when turned OUT (leans pilot circuit) and less air when turned IN (enrichens pilot circuit).

Good Fortune!