1978 KZ100D Z!R Project

I got this bike in Sept. 2017 from a friend who knew some of its history. It was virtually complete, but not unmolested. The worst part was the wiring. It had several melted/broken wires around the gauges, and about 20 splices sealed with electrical tape. Also a relay was put in the circuit to power the Dyna S ignition. It has take me and pro motorcycle tech/friend making house calls about 50 hours to repair most of the damage, removing the Reserve Lighting Module, Turn Signal Control unit, Fuel gauge, Ammeter, and replacing the left handlebar switch with a Euro-spec Z1 unit. So the headlight/taillight failure warning lights have gone by the wayside, too. As of now, the only problem is no brake light, and it looks like the headlight is on low beam when the highbeam is selected,(and vice versa) but I may be wrong about that one.
I had the rear wheel off to have a new tire put on, but when remounting, a problem occurred: when torquing down the axle nut, the wheel started to lock up at about 50 ft/lbs. Turns out the bike had a longer axle (from an H2), and the correct collar for the left side of the wheel was missing. I'm still trying to source one. In between these events, we did a 530 chain/sprockets conversion.
It's getting late, and I'm tired, so TBC. Just wanted to get this thread started.

Right on! Get her done! I have spent countless years trying to get mine going. So many things that take our time and money away from finishing our toys. I have had this bike four years already and I have a few minor gremlins with the start on off switch and the headlight wires. I need a few things but for sure I have an 80 LTD that I have very little to do to finish it off. I tell you if we get many more warm days I think I am going to finish it and ride it before it snows!
Good luck on your project and keep us all posted on the progress.

Well, yesterday was a bad day in the shop. My friend came over to help bleed the front brakes and install the exhaust and carbs.
First, after fitting the new manifolds to the head, we realized I had ordered, and been sitting on for 2 months, the wrong ones. I forgot that my bike has Police bike CV carbs. Fortunately, the vendor is accepting them back for a refund, and I ordered the correct ones.
The major problem is with the front brakes. I rebuilt both calipers with new piston seals. I checked them on the bench with compressed air, and the pistons moved forward and back nicely. The master cylinder was rebuilt with the K&L kit. After that, I read on our forum that the 2 small ports on top need to be cleaned out, or the bleeding operation will fail. That is what happened. My buddy apologized, took the unit off (PITA), and sure enough, the smaller one was clogged. We cleaned both ports out and verified their potency with light and compressed air, also checking that the piston seals were pointing the right way and everything was right.
Then to bleed again, using a MityVac. We put at least 4 reservoirs full of fluid thru the system and got all the air out with no leaking, but the lever was loose as hell, and the calipers pistons were not doing jack.
To take the MC off again and buy another kit and rebuild yet again seems futile. I will take the calipers off again and bench test them, but since they weren't leaking, I don't think they are the problem.
I guess I should borrow or buy another MC just to see if it will pressurize the system, on or off the bike. If it does, great, but I assume the OEM MC is rarer than hen's teeth, and costlier than a really nice brand new handlebar mounted MC.

Before taking it all apart try this. Don’t know if it will work for you or not but just try it. It might. I had a problem with my z1r master and someone told me to tie the brake handle closed. After so much working and pumping, by hand, with the vacuum pump I was going to give up. I tried it and the next day I came back and let the handle go and it was hard as a rock to come back. I could t believe it but it worked like a charm! Just make sure when you do this that you keep the level of fluid up or it won’t work.

Glad it worked for you, but I don't understand 100%. You lock the MC on the compression stroke, OK. Then you keep sucking with the vacuum pump, or just leave it locked overnight? I'm willing to try anything at this point.
Thanks

jeffz wrote: Glad it worked for you, but I don't understand 100%. You lock the MC on the compression stroke, OK. Then you keep sucking with the vacuum pump, or just leave it locked overnight? I'm willing to try anything at this point.
Thanks

Your problem sounds pretty severe for the rubber band trick.

The rubber band trick is for when you know you got all of the air out, and the lever still feels like it travels too far. With everything sealed and ready for normal use, you squeeze the lever, then put on a rubber band to keep the lever pulled and let it sit overnight. Somehow it takes all the slop out of the workings, like seals that are not seated exactly where they will eventually end up, or if the seals were distorted during assembly.

Yes. I spend probably two hours ducking with it and was about to lose my mind. Finally read on a post what loudhvx mentioned. You tie the brake handle to the bar. All the bubbles trapped inside come out and it will gain compression. If it works for you great, if not then? But it’s worth a shot. Simple things first. So I took the lid off and topped the fluids off at the fill line and let it happen. It literally didn’t need to be bled when I untied it from the bar. It’s like gravity bleeding or something. There might be air trapped somewhere. Just check on it a few times to make sure the levels are up. The next day I went to the bike and it pumped hard. All the air that was trapped left allowing fluid pressure to flow again.

It works right away. I noticed a few air bubbles start to come up. After two hours I got pressure but it was still weak so I retied it and left it overnight. I think it’s possible this trick will work for you.

loudhvx wrote: The rubber band trick is for when you know you got all of the air out, and the lever still feels like it travels too far. With everything sealed and ready for normal use, you squeeze the lever, then put on a rubber band to keep the lever pulled and let it sit overnight.

It sounds like you've done everything right. I agree with the other posts saying you should let it sit for a day or two see what happens.

I discovered this accidentally myself. I pumped several bottles of fluid through the front brakes and the lever still pulled all the way to the bars. I walked away in frustration and when I came back the next day the brakes worked great. I don't think you necessarily even need to hold the lever down. I think you just need to wait for all of the small bubbles to rise to the top.

Yes, the bubbles need to bleed through and for that to happen you need to tie off the lever.

Today I visited a guy who used to own a mcy. repair shop, to buy a rear axle spacer and an NOS rear brake light switch. I shared my problem with him, and the fix saxjonz suggested. He said he'd heard of it, but it only works if you have pressure and you want to get the last little bit of air out. He insists that the innards of the MC were not assembled right, and that if the cups were put on backwards, it would act like mine. I could swear they were on right, but I will tear it apart again. It has to be massively wrong somehow. He also said you can't put a regular KZ MC on the handlebars. I bet you could IF you put a flat handlebar on it. But then I couldn't ride it with
my 61 year old back.
Then he showed me one of his Z1R boxes. A couple headlights, a reserve lighting module, fork ears, and a complete front MC with reservoir. He said he had 3 of them! Doesn't mean he'd sell one cheap, tho. I asked for a price, but he just said "a lot". He did offer to
help if I brought mine over, at least.
Thanks to all you guys for responding, I was really feeling down, but now I'm ready to get back at it!

Well, you know, it’s possible it wasn’t assembled right. On mine I had to replace that brake hose between master and reservoir because I broke it changing the steering bearings out.
Try it. If tomorrow that trick doesn’t work then tear it apart.