1980 KZ750H Cafe Build

So here's something... I performed a leak down test, and every single intake valve was leaking considerably, as evidenced by a low reading and air blowing through the intake port each time. I had the cam cover off so I could check whether the valves were open, and the exhausts seemed good. I'm wondering if this was shimmed incorrectly by a previous owner, who then couldn't get it running and decided to park it; I haven't checked valve lash, but that's on the to-do list. Regardless, the engine is out and I'm continuing to clean parts.

Z1 Enterprises sells those jets you stripped. They can be a real bugger to get out sometimes. Key thing is finding a screwdriver that fits the slight TIGHT. I ground down a larger screwdriver until it fit properly. Even at that, you may need to put a torch on the tower to heat things up before they will come out.

Also realize that even after you remove those jets there are still brass parts that fit down into the carb passages that must be removed. To do this I use a wood dowel and push from inside the carb throat to get them loose.

Good luck

I pulled out those parts (bleed pipe above the primary main jet, needle jet orifice), but left the air jets for fear of mucking them up. I was able to clean everything with pipe cleaners, guitar strings, and compressed air.

The carbs are back together and float levels set to service spec (4.0±1.0mm). Since wet float level is measured from the carb body-float chamber split line, I was able to dial the float level in fairly accurately by setting dry float height to ~.875" (~22.5mm; my mic is SAE only), as measured from the carb body to the bottom of the floats with the carbs upside-down. I dialed that in with one carb and successfully hit the service level on the first try for the others.

I would be done, HOWEVER the choke linkage is giving me fits; specifically, the 2-3 interface isn't returning no matter how much I wind the return spring. I've loosely assembled the carbs in the mounting plates to ensure free rotation of the 3-4 choke shaft to no avail. The manual doesn't show a washer between the 1-2 choke shaft and the #2 carburetor, but the end sticks out slightly, causing the spring to move into the smaller diameter and lose much of its tension. I've seen a "fix" for this damn spring, but will try a linear spring to assist if all else fails.

I think I put a small piece of soldering wire in that place, to prevent the spring from falling into the smaller diameter.

I would say the last winding of the return spring is bent to an smaller diameter and need to be bent back like other windings.

That spring is jacked up for sure. Looks like you tried to wind it too tight. Shouldn't be necessary.

The choke shaft, which connects the carbs in pairs, should rotate smoothly and with minimal effort. If that's not the case something is misaligned. You might want to try loosening up all the gang bar screws and see if that helps. If not, loosen up the butterfly screws a little and try aligning the plates. Once you find the proper position for everything then evenly tighten everything up.

I got the carbs finished. Luckily I had another choke return spring. I was able to realign them to free up the choke. I blasted and coated the bowls and diaphragm covers in bronze, which I'm a big fan of.


I've been mainly ordering parts and blasting/powder coating what I have, but was able to rebuild my forks. I made a 2" drop for the damper rods and cut the springs accordingly. The lower forks were also blasted and coated bronze (photos coming). I replaced the air fittings with set screws (M10-1.25 for reference). I'm going to see how I like this setup before turning to aftermarket springs (and cutting down the spacers instead).



I also found a set of Zephyr 550 wheels, which are wider than the KZ. I'm still working on spacers, but it looks like I'll need to shave the outside of the speedometer drive to center the front wheel. Brembo calipers from a Ducati Monster are also in boxes, along with Zephyr rotors. The Duc has the same 17mm axle diameter, with a rear disc diameter 245mm vs the 240mm Zephyr. This means I might not have to fab my own bracket.