TOPIC:

Are the float levels pictured below within tolerance? Should I redo them until they are spot on? The tubing used has an outside diameter of 10.25mm, so they are only off by 2mm between the left two tubes. The left most tube is 5.5mm under the bottom lip of the float bowl. I probably need to bring them all up a little bit.

History: The bike ran great a couple years ago, then I caught it pissing fuel out of the carbs when on the kickstand. My buddy approximated the float heights without tubes and it ran like crap -- way too lean. Then another friend helped and it pissed all over the place. It sat for a year, and when we trouble shot it, we found the o-rings between the two pairs of carbs were bad (and may have been the original issue!). The electric system also had a bad sensor on the ignition plate. Due to parts availability, I had to upgrade to a Dynatek electronic ignition and coils due to the bad ignition, so that is done. We got it semi-balanced and running, but it is far from perfect like it was before. The valves should be fine since it ran great before, so I am trying to avoid taking off the valve cover.

Carbs - thoroughly cleaned
Diaphragms are in great condition.
Replaced the float needles and gaskets throughout the carbs.
New Dyna ignition, coils, wires, and spark plugs.
Checked the vacccum line that has those two vac plate leaf things. Pardon my crude description. Good vac lock.

It seems like the electric charging system is barely keeping up, but it has over the past few hundred miles.

I have not balanced the carbs due to not having a 4x mercury vac gauge (manometer?). I could take it to a local shop if that is the last issue.

I just bought new airbox-carb rubber boots and new vac lines that I will install soon.

Suggestions? Thanks in advance, you guys are always amazing and the forum has helped a ton from past articles and posts.

I don't know what the OD of the tube has to do with it, but they all look a little low to me. It would be easier to see if you marked the min and max lines on the float bowl with a Sharpie.

On a side note, it's amazing how handy a Sharpie is in the shop.

I forgot to say earlier: the bike has poor starting, I have to give it gas and keep slight idle while it warms up. Then things idle alright, but the power is crap until full throttle jet is reached. Slow jet should be clean, but one is stuck so we were unable to confirm. It also runs poorly in the morning when things are a little cooler.

The sparkplug pic below is from around 300+ miles of running, I have not done a full throttle kill to see the color. I found the spark plug nipple nubbin to be loose when I took the plug wire off, maybe that contributed to bad spark?

Steel: Since it is hard to judge the measurements, I gave the only one I could so the float height and disparity between bowls could be determined. I will dig in to the floats and try to bring up the level a little.

Shortening plug wires after float balance and raise.

What does it tell you in your manual for Service fuel level.
I always go for equal to the lower flange edge (@ 3mm under Join) even though it is supposed to be - 0.5 +/- 1 mm above bottom edge of carb body (Join) as i cruise 90 % of the time and give it a clean out on mountain ranges (when i can).How do you use your machine ?
Roughly by your photo i reckon they are all too low - go for that Lip or lower edge flange if you ride like a grandpa like me.It will probably take some time but is well worth it,
Hope that helps .
.

Make sure those plug caps are on properly. Maybe come in from a slight angle if they are not clicking on straight.
How have you tried cleaning that Slow (pilot) Jet. I ended up finding the very smallest pin i could and "VERY" carefully and "VERY"slowly pushing it through using some small pointy noses.. (have you got any spares just in case)
What are your mixtures set at.
Up the float heights and see how that goes.

Back up and running, but there is a strange vibration during acceleration that kind of has a rattling sound. See detail below:

I removed all the slow jets (and the annoying plugs that go on top) and found one that I couldn't see through. I remember cleaning all of them until the pinhead hole was visible down the jet length. The jet must have clogged from something in the fuel line or carb after we got it back together. It took a small sewing needle to dislodge, some carb cleaner, and a fine air blower on the compressor.

As for the balancing of the floats, I fought it and kept getting crap readings after much careful adjustment. I put them back on just to see, installed the new rubber airbox to carb boots, and it fired right up!

The battery died right after that, but the next day I added some distilled water and gave it a trickle charge.

Wondering what the vibration is from... is that a possible issue with the still unbalanced floats, or do I need to have them vac balanced for equal power at each carb?

Can I add an audio file below or a video link?

Can you describe this vibrating sound and where you reckon it is coming from ?
Is your bike starting first time
Have you got a manometer ?

The vibration happens mid throttle mostly after fast acceleration at around the 4k zone, but ceases as I hit 5k ish. The bike runs great at cruise, then when I downshift it happens again around that 4k zone. It is far more noticeable when the clutch is not engaged. You can hear and feel it in mid to semi high tones as a very fast vibration.
Bike starts first try within 2 seconds and idles great now, begging to be unchoked. I do not have a manometer, but my womanometer works pretty consistently!-).

: )
Not sure what to say about womanometer - best be diplomatic.
Do you have an idea of where the noise is coming from. Is it a Buzzing sort of noise or more a rattle ?
Do you have access to a carb synchro set. Definitely needs to be checked if all else is good.
How did you go making an audio file or video of the noise?

The gentleman at the local bike repair shop said that nothing within the motor would cause the vibration, and that it is probably something else on the bike rattling when I reach that frequency (cycles per second, or 4500 rpm).

He stated the carbs were probably within good running levels based on what I had done, and that there was probably an idle mixture issue that needed to be addressed before he did a carb balancing with the manometer that he would not rent out.

Starting new thread for the idle mixture.

air fuel mix topic link:
kzrider.com/forum/2-engine/595513-kz750-...ilot-mix-1981#645528

I would assured that your ignition advance mechanism is working properly and lubricated. Also the idle air adjustments could have a slight effect in this range. The throttle opening and rpm range mentioned are far to high to be affected by a Carb sync IMO.