TOPIC:

I just finished building a 1981 KZ1000 with R6 suspension. Solid idle at 1000 RPM. Mechanical advancer fully advanced at 3500rpm. strong sparks. fuel level set per manual.
This is what I have.
-New Dyna S
-Old Dyna 2.2ohms Coils (don't know how old) with 1.6 ohms ballast resistor. Cold tested ok.
-Dynojet Rejet kit for pods and 4-1 exhaust
-new bettery
-new wiring harness.

Bike runs well until 6000 rpm and it feels like it is hitting a rev limiter. tach needle just bounces off around 6000-6200 rpm range. Tried with choke engaged but didn't make any difference at all.
I'm thinking coils but wanted to hear more opinions before spending $130 for new 3.0 ohms coils.
Any inputs are welcome,

Never mind... I was way off base with my suggestion...

Subbie79 wrote: ...1981 KZ1000...Bike runs well until 6000 rpm and it feels like it is hitting a rev limiter. tach needle just bounces off around 6000-6200 rpm range....

Handsome bike!

Does inability to exceed 6000-6200 rpm happen also with free rev in neutral?
Or only when under load?

Good Fortune!

close spark plug gaps to .020 and see if it will rev...... if so , ignition related.

Wow that bike is beautiful, good job. Since there was no effect when you applied the choke I would say it is ignition related. I bet your problem is going to be with your old coils. The Dyna S requires 3.0 ohm coils.

tach needle just bounces off around 6000-6200 rpm range.

Digital tachos often go whacky and bounce around if there is an ignition fault, as they are fed from the coils -ve .
At high rpm the coil gets less 'dwell angle' to recharge between sparks -just when it needs the most .

I had this before when ATU's stick and are not advancing right... but you strobed the timing to full advance at 3500rpm? The old pre zx mechanical advancer ATU's go to full ignition advance really low rpm anyway.

Hi ..you've gotten a lot of good advice ..sure sounds like fuel or electrical ..and I'm just barely hedging towards fuel..opening the choke should have done something ..picked up if lean ..stumbled if normal or rich ..vacuum petcock can cause a lean float bowl because of dirt, leaking vacuum hose..put it on "primary" and see what happens ..you can also open up the float bowl drains, drain into a container for 30sec (be careful), watch for good fuel flow and check for for a functional, non-restricting fuel tank vent ...carb vacuum caps and intakes sealed? ..I like Permatex II instead of silicone ...carbs clean? .......electrically, the dyna S should fire 3 & 2.2ohm coils..I believe you can verify that at the Dynatek website ...one of the gentleman at dyna and I had a conversation about a ballast resistor for points and a 3ohm coil..different combos and resistance ..couple years ago ..pretty sure I'm telling you right ..I'd just do a quick check and drop the ballast resistor ...if all that checks out I guess I'd head toward mechanical camshaft and crank timing ..valve lash and compression check....could be aggravating like one coil/module breaking down at speed ...read the spark plugs ...hope I helped a little ...

Oops! ...

With a Dyna S, the dwell angle is fixed at over 300 degrees.
Dynatek says the Dyna S requires 3 ohm coils as the minimum without ballast. The ballast makes up the difference to limit the current, which should be fine. In this case, two 1.6 ohm ballasts is more than enough to compensate for the low resistance coils. It would be better to run two 1 ohm ballasts. Each one in series with a coil on the positive side.
The current setup theoretically should work ok as long as the engine compression is stock, and the spark gap is stock, and you are running only one or zero resistance items in each high tension path (resistor wires, or caps or plugs).

Usually, if the problem was from inadequate dwell, or too-wide spark gap, or too high compression, it will still rev to redline with no load (neutral) and very light throttle (as Patton suggested). The problem would show up under larger throttle openings while the engine is loaded down.

If you are using a single 1.6 ohm ballast, I would do what kz1r78 suggested, and try a brief ride without the ballast. Because the dwell overlaps on the Dyna S, the current in one coil will be affected by the current in the other coil due to the ballast.

These are just suggestions before laying out the cash on new coils.

Is the tach an aftermarket electronic tach? Does it require a tach adapter to get signals from two coils? If so, I would temporarily disconnect all of that.

If you can get it to redline in neutral, Have you actually watched the CV slides go up to confirm they move up? In neutral, if you crack the throttle to WOT, the slides should open most of the way (or all the way) just before you have to close the throttle. This is not good for the engine, so don't do it too much, and don't get your face too close to the carbs in case they decide to back fire, wear some glasses. Watch them from behind the bike if you can get someone to work the throttle. or better yet, mount a video camera and do a short ride.

Fast forward to 5:30, he only manages to actually go WOT for a few brief moments.

I really appreciate all the inputs. Sorry I had one busy week and didn’t get a chance to give you guys an update. Today I got off work early for the holiday and finally rode my bike.
I initially thought the coils were not getting enough current so I bypassed the ballast resistors. (Dyna S and 2.2ohms Coils). But it is still revving only up to 6000 rpm. However, It does rev all the way to 9000 in neutral. I didn’t get to adjust the spark gap yet.
I tried the choke on and noticed slight improvement in midrange acceleration. (2500-4500 rpm range) but the engine dies as I come to a stop. Doesn’t affect 6000rpm ceiling neither. Tried Tank cap open but no joy.
Mechanical advancer is fully functional, as I checked with timing light. Tachometer is OEM.
CV sliders go up and down no problem. Re-adjusted the fuel level per manual.

Are my main jets too small? I don’t remember the size top of my head but still, it wouldn’t explain the sudden cut out at 6000rpm.

If inadequate dwell is causing this, would closing the spark gap make any difference? Wish I could adjust the plugs right now and go for another ride but gotta go to a thanksgiving dinner at my in-laws.
If spark gap doesn’t have any effects on this, then I guess the next step would be the new 3.0 coils.
It may take a few weeks to get the coils but I will definitely keep you guys posted.
Again thank you all for the ideas and Happy Thanksgiving!

Subbie79 wrote: I really appreciate all the inputs. Sorry I had one busy week and didn’t get a chance to give you guys an update. Today I got off work early for the holiday and finally rode my bike.
I initially thought the coils were not getting enough current so I bypassed the ballast resistors. (Dyna S and 2.2ohms Coils). But it is still revving only up to 6000 rpm. However, It does rev all the way to 9000 in neutral. I didn’t get to adjust the spark gap yet.
I tried the choke on and noticed slight improvement in midrange acceleration. (2500-4500 rpm range) but the engine dies as I come to a stop. Doesn’t affect 6000rpm ceiling neither. Tried Tank cap open but no joy.
Mechanical advancer is fully functional, as I checked with timing light. Tachometer is OEM.
CV sliders go up and down no problem. Re-adjusted the fuel level per manual.

Are my main jets too small? I don’t remember the size top of my head but still, it wouldn’t explain the sudden cut out at 6000rpm.

If inadequate dwell is causing this, would closing the spark gap make any difference? Wish I could adjust the plugs right now and go for another ride but gotta go to a thanksgiving dinner at my in-laws.
If spark gap doesn’t have any effects on this, then I guess the next step would be the new 3.0 coils.
It may take a few weeks to get the coils but I will definitely keep you guys posted.
Again thank you all for the ideas and Happy Thanksgiving!

I sure wasn't expecting to be impressed when I clicked on this thread....figured another butchered Kawasaki... WAS I EVER WRONG! ..... Nice Work!

The Jet Kits come with different size mains for Stage I and Stage III. Look at your jets left over in the kit. If there's any larger that 112 or so.... put them in. You might have just grabbed the wrong pack of main jets.

Again ....Congratulations on your project

I want to know more about the carbs before he buys anything. I suggest lifting each slide, hold thumb over large vent at the top, then let the slide drop. If quick, that's it, if slow, it's another thing ready to go. Diaphragms. I'd put my money on them.
Steve

SO I tightened the spark gap to 0.020", ballast resistor still bypassed, but it is doing the same thing. 6000 rpm.

I pushed the sliders up and blocked the air port, and the slides come down very slowly. takes about 40 seconds to fully down position. I think diaphragms are ok.

My main jets are 165. Stock was 122.5.
Dynajet kit came with 155, 160 and 165. Manual recommends 165 for pods and exhaust. (main air jet also changed)
Should I try smaller main jets?

Carbs were cleaned and re-assembled with new o-rings.