KZ1000 Drag Bike Dyna Ignition Timing

I have a kz1000 drag bike that I'm still trying to figure some things out on. I bought it as is, and it has won a lot of races by the old owner, but long story short, I'm still trying to get everything tuned in and consistent. It is running about a half second slower here in MN than Vegas, and the density altitude is considerably better (lower) here. The guy I bought it from sold it for a friend, and while he knows a good deal about the bike, he didn't have all the tuning specs on it.

Anyway, as for the ignition timing, I found a good tutorial on here for setting it. The 3-slotted plate was set at full retard when I got the bike, so I figured that might be off and slowing it down. The tutorial said that the screws will probably end up close to the center of the slots for the correct timing. However, when I checked it with a timing light, it read 40 degrees when the plate is turned full retard (where it was when I got it). So my question would be, is 40 degrees of timing sound right? Or is there something not right here? I searched and couldn't find a good answer on this.


Based on the engine number, it's a 1980 block. Here's what I know (or was told) about the bike:
1075cc kit with mtc or wiseco domed pistons (guessing around 11:1 compression since it's push-button start)
J-head with light porting
.400" lift cams
Mikuni VM33 smoothbores. 145 main jets. Does this sound close for 1000ft. elevation? (was told it was jetted slightly fat for Vegas)
Vance&Hines megaphone
Dyna 4000 ignition
Air shift
Auto shift
Lock-up clutch
Etc...

Was told in ran 9.9 to 10.0 in Vegas with about the same size rider as me. The best run here was 10:47.

I checked compression and it was about 190. I plan on checking the fuel level/float height before my next race in a week.

40 degrees is correct for full advance.
This should be achievable with the mounting screws towards the centre of the slots.
It is common to have the wrong rotor or ATD which results in having to rotate the back plate to its maximum adjustment to get the correct timing.
Your rotor is stamped either 3 or 3A.
If you have a 3 you probably want a 3A and vice versa.

zed1015 wrote: 40 degrees is correct for full advance.
This should be achievable with the mounting screws towards the centre of the slots.
It is common to have the wrong rotor or ATD which results in having to rotate the back plate to its maximum adjustment to get the correct timing.
Your rotor is stamped either 3 or 3A.
If you have a 3 you probably want a 3A and vice versa.

Ok, thanks for the quick reply. I don't see anything stamped on it. So if the timing is correct, should I just leave everything there be?

You also must take into account the humidity in MN is way more than LV

mxhideout wrote: Ok, thanks for the quick reply. I don't see anything stamped on it. So if the timing is correct, should I just leave everything there be?

If you can get the timing correct as is then it will be ok to leave it but having the back plate on the limit of the slot is not ideal and leaves no scope for further advance adjustment if needed.
Flipping the back plate (which isn't symmetrical) can sometimes enable the timing to be set with the slots central as they should be .
If trying that be careful of damaging the threads for the tiny pickup screws on re-assembly.

I've not messed with a 4000 box but my 2000 is the same way set at the end of the slot's.
With the 2000 you set base timing at the plate and all the advance is in the box which is programmable.

More info like the 60' times, 1/8 et and mph along with your 1/4 et and mph. any kind of data logging? Bike bogging, spinning, slipping clutch too long, launch rpms too high, too low? Most bikes slow down with new rider due to little launch scenarios, proper stance, tire pressure, launch rpm, etc. etc. list is long and they can eat a whole second or more up pretty quick. Back to timing, Do good plug reads, keep things on the safe side till you learn it's habits and enjoy the path to busting into the 9's

Les

Thanks for the replies. I realize the humidity is higher here, but shouldn't the 2500 (here) vs 5500 (Vegas) density altitude make up for that?

I've been testing different tire pressures and wheelie bar heights, but I got set-up info for that from the previous owner. 9.5-10 PSI for the rear. Launch RPM is 7500. Shift RPM last race was 9750. It was at 10k RPM, but I was told to bump it down to 9500-9750.

Average run from first weekend of racing was:
60': 1.429
1/8: 6.663
MPH: 103.87
1000: 8.744
ET: 10.567
MPH: 120.67

I dropped shift RPM down to 9750 the next racing weekend, and that got me into the 10:40s. I plan on going down to 9500 next weekend.

My racing partner/teacher has watched some of my launches, and depending on how well the track is prepped and how hot it is, he says the bike does bog a little. Might just be because of the lock-up clutch and that the bike doesn't have a lot of horsepower to begin with. I'm using an MPS air clutch with a delay box, and it's launching off the 2-step. I don't think the clutch is slipping. I pulled the clutch apart and everything looked pretty much new still.

It's also hard to get a good plug reading because the guy I bought it from said the plugs will also be black unless I shut it off right away, but I don't have anyone to tow me back. I'm guessing the pilots are rich to get it to idle, based on what I've read about the VM33's.

I'd like to hear more about the 33's.
Steve

swest wrote: I'd like to hear more about the 33's.
Steve

From me, or someone that knows more about them? I had to replace the needle and seats because at least 3 of them were leaking. I tried cleaning them with cotton pocks and rubbing compound, but that didn't seem to help. 100 bucks for those little things. I started looking for RS36/38 carbs.

I have them. I was interested how yours were set up.
Steve

I haven't torn them all apart, so I only know that it has 145 mains.