TOPIC:

Yes. Just a thought since I'm at a stand still now?

kzdcw wrote: Correct me if I'm wrong. Does the caliper piston ( solid portion ) install at the bottom of the caliper bore and ( open portion ) of the brake caliper piston face up? That's the way I have them installed but was thinking if I reversed them, would there be more brake fluid inside the open portion of the piston to exert more force therefore pushing the pistons more against the brake discs when the brake lever is applied ?

I believe you have it correct, with the open end of the caliper piston pushing against the disc.

Good Fortune!

I would speculate that the calipers at hand are designed with a limitation on how far the piston may protrude, and if so, they may function normally on the thicker stock rotor, but not function normally on the thinner rotor.

Perhaps the calipers could be used with the thicker rotors.

Am thinking the thinner rotors were adopted with dual disc front brakes in order to reduce unsprung weight.

The factory offered a dual disc conversion kit for the Z1 that included another same 7 mm thickness disc together with a larger master cylinder and associated brake line parts.

I believe the thinner 5 mm disks were adopted for the 1976 KZ900 LTD.

Perhaps swest can elaborate on how his stock calipers cope with both the 7 mm and 5 mm rotors. Maybe his calipers aren't the exact same model as the calibers at hand.

Good Fortune!

Swest made indication that his calipers worked for both 5mm and 7mm rotors?

Looking at various part #'s on the cmsnl.com website it shows different part #'s for both models ( LTD and KZ ) calipers and rotors.

Without getting to much into all the part #'s it did show that the solid rotors of both 77-78' LTD and KZ's different. And the 79-80' KZ/LTD drilled rotors different as well

# 41080005 77-78' KZ1000 Solid disc brake rotor
# 41080007 77-78" LTD Solid disc brake rotor
# 410801022 79-80' KZ/LTD Drilled disc brake rotor

As far as Calipers, different part #'s as well.

# 430411008 77-78' KZ1000 Single disc brake caliper
# 43041033 ( R ) # 43041032 ( L ) 77-78' LTD Dual disc brake calipers
# 430411025 ( R ) # 430411024 ( L ) 79-80' KZ/LTD Dual disc brake calipers

Just got back from Oregon. 3AM. I was thinking about this. Are the forks stock? If not, that might be the problem. To be fair, I have H2 calipers on my bike. I had Z1's before with thicker disks and ran them until I bought the drilled LTD style recently. They may have more throw than the stock ones but I doubt it. You might try a washer or two between the caliper mounts and the fork legs to make up the difference. I'll post picks of mine tomorrow.
Steve

With the 5/8" MC how far does the lever move when you pull it in before it gets tight and stops? Also, once the lever is tight and stops moving does the front wheel spin freely or are the brakes working at least a little? Ed

There is No braking at all. As I said earlier in the Post that I even went back to the Chinese 1/2" bore Master cylinder ( which was working before with the Stock solid single disc ) and nothing changed?

Both Calipers bleed just fine at the release valve ( no air, at least that I can tell ), but don't move the caliper pistons enough to grab the brake discs and stop it?

Stock Forks. I could try a couple over washers behind the caliper mount at the fork leg mounts and see what happens?

Today I was going to take everything apart and bench test it and try to see just what is going on?

It sounds like you still have air in the brake lines. This is not uncommon when changing out master cylinders and brake components. Sometimes air gets trapped in the splitter or in the calipers. If you're using a right hand caliper on the left side, or a left hand caliper on the right side this can happen if the bleeder is not vertical when bleeding. Swapping sides usually leaves the bleeder in more of a horizontal position rather than on the top of the caliper. Ed

You can leave the fitting cracked open, Make them leak, hold the lever in and work down the line. On my right side the bleeder is up side down so I bleed it with the Banjo bolt.
Steve

I reversed the caliper pistons where now the open end faces downward and closed end faces upward which makes contact to the back side of the brake pad. It was suggested that I try that but so far hasn't made any difference? The bleeder valve on the left side caliper faces straight up, the bleeder valve on the right is at the 10 O'Clock Position. So I don't think their position would restrict air being bled out during the bleeding process. I also put a 2 mm washer between the mounting plate of the caliper and the fork mounts, made no difference either.

So, right now going to remove both Calipers and hook up to a Master cylinder on my work bench and see what happens? It will be direct brake lines from the Master to the calipers, which will eliminate the splitter. I'll report after a little while and let you know the results.

If it were me and I decided to use washers as shims, I'd solder or braze them together to make them one piece.
As I remember it, I turned one arm over to make it work on the other side. There was a cut out and I used a washer to fill it. No problems.




I've always meant to install a fitting for the bleeder and tap out the hole to fit a banjo bolt.
Steve

Ordered a New Master Cylinder 5/8" . The problem I think I may be having is trying to test this Brake Set-up with a couple of used but functional masters that I had off of Late model Kawasaki's. They appear to be functional by getting brake fluid to the calipers and able to bleed off the air. Put maybe they're not supplying enough brake pressure? What throws me for a loop, is the Chinese 1/2" master I was using before was brand new and did work fine with the single stock dic brake set-up?

I'm also think Im going to invest in a brake bleeder and vacuum pump to help with this bleeding process?