Kz650b3 to dual disc

No eBay APP ID and/or Cert ID defined in Kunena configurationHi, 

I’m trying to convert my kz650b3 with the rear facing brake callipers to dual disc brakes on the front, I managed to source some unittrack gpz750 callipers which bolt up. I just need to figure out what discs fit? Am I correct in saying it’s the kz1000 from 1978-80 4 bolt ones that do? In the smaller thickness for example this one 710-127635-2958-0

I will source a 5/8 master cylinder too. 

cheers
aaron 

kzrider.com/forum/5-chassis/610218-kz650...onversion-confirming

Hi dohc, I have already seen that thread, I have a b3 with the forks facing backwards. i have put up the gpz callipers and they do not fit the standard single 296mm disc. So a z1 disc will not fit either.  

i am thinking z1 callipers will fit along with z1 discs of 296mm 

 

Looking up your fork on Partzilla yours are the same as all of the 650b, and the kz1000a models. Don’t try to reinvent the wheel. I’d source kz1000 parts. Kz650 c might work also

wrote:

Hi dohc, I have already seen that thread, I have a b3 with the forks facing backwards. i have put up the gpz callipers and they do not fit the standard single 296mm disc. So a z1 disc will not fit either.  

i am thinking z1 callipers will fit along with z1 discs of 296mm 


 

First off, I think those calipers are not compatible with your fork lowers.  Are both mounting bolts threaded in place in the photo you posted?  If that caliper is mounted, it does not sit at the correct angle.  A smaller disk will just move more of the brake pad surface outside the radius of the disk.

I think you want to find calipers from a dual-disk setup 78-80 KZ1000 or KZ650 (and maybe the KZ750?).  They all use basically the same calipers, but there are two different sized pistons, 38mm and 42mm.  The stock KZ650B3 left side caliper should use the larger 42mm piston, so finding a right side caliper to match, that is also 42mm, seems like it would make sense.

This is what I did on my KZ650-B3.  

As for disks, the 77-80 KZ650 & KZ1000 (and maybe the KZ750?) use 4 bolts and any one should bolt on to the KZ650.  As you mention, the single-disk disks are thicker.  Using two single-disks together would add a lot of extra weight to the front wheel, which is not good.  

I believe if you found a set of the thinner KZ1000 dual-disks, these would line up with the stock KZ650-B3 caliper (and a similar one for the right side).

As mentioned in the thread I linked, the dual-disk KZ650 (C and D) used smaller diameter disks.  The calipers were the same, but the fork lowers were different.  The mounting points on the KZ650 C and D fork lowers are closer to the wheel.  Using KZ650 C and D disks on KZ650B3 requires changing the fork lowers.  I did this on my KZ650B3, and it works if you can find the parts.

I liked the dual-disk setup with the smaller disks on my KZ650-B3.  They worked really well.  

If you can't find a right-side caliper that matches your stock left side, you could look at the early 80s calipers.  I have heard that the 81 to maybe 83? or so calipers will fit on the earlier forks, but I haven't tried it myself.  With these, the caliper body is very similar to those GPz calipers you have, but the mounting bracket is much different.  It doesn't have the speed holes that you see on the GPz bracket.  Maybe it would mount at the same angle as the 78-80 KZ caliper?
 

DOHC, the caliper he needs says 1 11/16 on it correct. That’s the larger piston 

wrote:

DOHC, the caliper he needs says 1 11/16 on it correct. That’s the larger piston 

Yes, that's right.  1 11/16 is 42.8mm, which I'm assuming is the actual piston size.

The "1 11/16" text is cast into the caliper body on the back side.  Here is a picture.

 

Also, here is a picture of the '81 style calipers that maybe could work?

 

Before you jump the gun, I just wanted to point out that earlier KZ's have offset disks, while later KZ like mine is straight disk. Caliper itself will bolt on from my experience, but bought the 650 fork from evilbay, so although seller said it's from 650 who knows what it came from.

I did not have the both disks back then, so I have no idea if it'll fit with the caliper on. At that time, I just needed a fork to mock up my bike as my original front was too far gone and leaking really bad, along with too far gone fork tube (rust pitted). I got a set of correct fork since then and properly rebuilded (I hope).

Appears the problem is the mounting points of either the caliper or the fork lower are not the correct. The caliper is not on the same axis as the rotor. Size nor offset will fix the. I see the lower mount needs to come away from the axis and the upper move closer. 

This might be an option. Been list a long time, maybe you can work a deal

www.facebook.com/marketplace/item/358431995840254/

Thanks for that however I am in the UK so shipping that wouldn't be very cost effective! 

I've managed to source two 5mm z1000 4 bolt front discs, and a 11/16 right hand caliper, however now need to try find a right hand bracket that fits my forks as it is one from a z1300 and does not fit. Might end up getting one lazer cut to match the otherside but mirrored. 

The C-C spacing on my forks is 71.5mm.

i install kz 1000 front disck, and left and right calippers. It is plaug and play. but you need boths breake lines and a better break pump, i stall a CBR 1000F brake pump.