# Custom Rear End For My Kawasaki.



## P.K. (Nov 15, 2015)

_Note:
I recently posted this in the "Project of the day" tread but realized it probably wasn't the right place.
Also, I'm planning to post some more from this project later on, so I started a new thread here instead._


Hi

I'm into customizing motorcycles and I'm currently building a new rear end for my Kawasaki H1.
Early in the project I decided to use a rear wheel hub from a 78 KZ750. After a while I decided that this hub is uglier than a monkey's armpit, so I set out to modify the hub just to make it look better.

Here are some pictures taken during the process.

First the "before and after" picture.



I used the big press at work to get that ugly flange off.



Flange removed and hub sand blasted.



I made a two-piece mandrel for chucking the hub in the lathe.



Mandrel fitted.



Center drilled in the other end.



This is close to maximum diameter for my small lathe.



Finished hub machining.



In this mosaic picture I'm making a new flange to replace the one I removed. The flange is made out of 20mm thick cast aluminum plate.



The finished flange.



I made an interference fit between the flange an the hub. The flange will be heated to 200 deg celsius before placing it on the hub.



A guide pin was used to "synchronize" the spoke holes.



The finished hub, drive side.



The finished hub, brake side.


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## kd4gij (Nov 15, 2015)

Very nice work.


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## jeff_g1137 (Nov 16, 2015)

Hi
Are the spokes smaller ?


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## Sitting on Blocks Racing (Nov 16, 2015)

Beautiful!


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## P.K. (Nov 16, 2015)

jeff_g1137 said:


> Hi
> Are the spokes smaller ?



I' not sure what you mean.

The original KZ750 wheel would have 4 different spokes because the right flange is smaller diameter than the left flange.
I made my new aluminum left flange such that left and right side spokes are identical (i.e. equal diameter on the spoke hole circles). This means I only needed two different spokes (inner and outer).

The spokes were special ordered from Buchanan's Spoke & Rim, who also delivered the rim correctly drilled for this hub. All they needed was a drawing of the hub.
The rim is EXCEL 4.25 x 18" (WM9) aluminum and the spokes are stainless steel.


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## P.K. (Nov 16, 2015)

Here is my Kawasaki H1 that will get this new rear end installed sometimes this winter.
The whole idea is to modify a 70's classic with modern components for increased handling and power, and to do so without loosing too much of the 70's look.



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## P.K. (Nov 16, 2015)

OK, back to machining.

I certainly wasn't going to fit a stock KZ750 brake rotor to my modified hub. They are humongous and wouldn't fit with my "modern components" scheme. Modern R bikes typically have a 220mm rear brake rotor so I needed to make an adapter to fit one of those modern rotors to my hub. Normally I would have parts like this water-cut and then apply some finish machining, but in this case I wanted to machine one from scratch with the help of my new rotary table. It was a bit of a challenge considering the shape I had given this part.

Here are a few pictures.












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## jeff_g1137 (Nov 16, 2015)

Hi
I meant the length of the spokes
Very nice work.
What size of lathe have you got, & mill ???
Have you any photos of the Lathe & Mill.
Love the bike, i have a 2004 BMW gs1200, my m8s had the H1 in the 70s, i think i had a 750 Custom


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## P.K. (Nov 16, 2015)

jeff_g1137 said:


> Hi
> I meant the length of the spokes
> Very nice work.
> What size of lathe have you got, & mill ???
> ...



The lathe is a HBM 290 Vario, an 11x27 bench lathe with a 38mm spindle bore.
The mill is a HBM 45 Profi, a basic Rong Fu 45 clone.
Cheap Chinese machines that can be found as a dusin different re-brands around the world.
Some pictures here: Lets See Your Shop!


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## P.K. (Nov 17, 2015)

Next up was the caliper bracket. The chosen caliper comes from a 2008 Ninja EX 650. The bracket that came with this caliper didn't fit very well with my swing arm so I decided to make a new one.
This is an example where I have the part water-cut and just do some finish machining afterwards. If I had a CNC mill I would have machined the whole part instead.

The water-cut blank next to the Ninja bracket.



I'm using a two flute 20mm mill with carbide inserts. It became obvious that my mill doesn't have enough rpm for this kind of tool.



Polished carbide inserts for non-ferrous metals only.
	

		
			
		

		
	




The caliper bolted to the bracket.



A rough check to see if it fits.
	

		
			
		

		
	




I made a stainless steel sleeve for the axle hole and it's a press fit.






I'm not just winging this a I go along. I actually have a 3D model and I make drawings of all the parts.


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## zmotorsports (Nov 17, 2015)

I think I commented on the other thread that you posted these pictures on, but I will comment again.  Very nice and impressive work.

Quick question, on the brake rotor hub did you machine the sections out between the rotor mounting tabs first and then set up each of the four tabs in the rotary table to get the radius around each of them where they blend into the center diameter?  I hope what I am asking makes sense.  Just curious as to your sequence of operations on that hub.

Mike.


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## P.K. (Nov 17, 2015)

zmotorsports said:


> I think I commented on the other thread that you posted these pictures on, but I will comment again.  Very nice and impressive work.
> 
> Quick question, on the brake rotor hub did you machine the sections out between the rotor mounting tabs first and then set up each of the four tabs in the rotary table to get the radius around each of them where they blend into the center diameter?  I hope what I am asking makes sense.  Just curious as to your sequence of operations on that hub.
> 
> Mike.



Yes, that is pretty much how I did it.
I  tok care when designing the rotor hub so that it would be as easy as possible to machine using the rotary table.
All angles are whole numbers and inner radii matches the diameter of the end mills I used. The outer radii around the tabs are exactly 180 deg.
Here is a drawing of the rotor: https://dl.dropboxusercontent.com/u/399336/Pictures/Posted_THM/Rotor Adapter/Rotor_Adapter.pdf


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## zmotorsports (Nov 17, 2015)

Thanks, that is what I was thinking, but was curious as to the sequence.

Again, fantastic work.  Thanks for sharing.

Mike.


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## jeff_g1137 (Nov 17, 2015)

Hi
"I made a stainless steel sleeve for the axle hole and it's a press fit."
why, why not just leave it, as is.
Great work, i must get a mill, & upgrade my lathe, it is only 10"x 22"
more photos or a video please


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## wrmiller (Nov 17, 2015)

What rpm did you run that 2 insert end mill at? I've not used one of those, yet, and am wondering what a good rpm for those cutters is? For example, my max spindle rpm is currently set to about 5100 rpm.

EDIT: Oh, and love the bike. Had one of those when I was in the Marines and basically ran it to death between the base at 29 palms and the colorado river where I spent many a weekend rafting/tubing and drinking beer.


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## dave2176 (Nov 18, 2015)

That is just beautiful work. Thanks so much for sharing.


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## P.K. (Nov 18, 2015)

jeff_g1137 said:


> Hi
> "I made a stainless steel sleeve for the axle hole and it's a press fit."
> why, why not just leave it, as is.
> Great work, i must get a mill, & upgrade my lathe, it is only 10"x 22"
> more photos or a video please



Thanks Jeff.

My first plan was to not have a sleeve but I needed some clerance between the bracket and the swingarm.
Instead of having a 2.5 mm thick washer between the bracket and the swingarm I opted to make a press-in sleeve that protruded 2.5mm out from the bracket.


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## P.K. (Nov 18, 2015)

wrmiller said:


> What rpm did you run that 2 insert end mill at? I've not used one of those, yet, and am wondering what a good rpm for those cutters is? For example, my max spindle rpm is currently set to about 5100 rpm.
> 
> EDIT: Oh, and love the bike. Had one of those when I was in the Marines and basically ran it to death between the base at 29 palms and the colorado river where I spent many a weekend rafting/tubing and drinking beer.



I ran it at 1700 rpm which is maximum on my mill. If you have 5100 rpm then you should be good.
I plan to replace the 4 pole 1.5 HP motor on my mill with a 2 pole 3 HP motor and a VFD. That should enable me to run 4000 rpm or even more.


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## gbritnell (Nov 18, 2015)

What a beautiful improvement to the Kaw. The lightening holes give it some great character. 
gbritnell


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## wrmiller (Nov 18, 2015)

P.K. said:


> I ran it at 1700 rpm which is maximum on my mill. If you have 5100 rpm then you should be good.
> I plan to replace the 4 pole 1.5 HP motor on my mill with a 2 pole 3 HP motor and a VFD. That should enable me to run 4000 rpm or even more.



That is basically what I have. Mine is converted to belt drive with a 3 hp motor and VFD. I won't go back to a gear head.


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## FOMOGO (Nov 18, 2015)

Very nice work on the 500. I rode an H2 with tuned exhaust that belonged to a friend in the mid seventies. It was a beast. You had to get out over the bars to keep the front end on the ground and it would bend the sprocket teeth from applied torque. Pretty tame by today's standards, but just amazing back then.  Will look forward to seeing the swing arm. Mike


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## P.K. (Nov 19, 2015)

Next up in my project was finding an axle bolt and chain tensioners. The guy that made the sving arm said to use tensioners from late Kawasaki H2 so I bought a complete axel with spacers and tensioners on eBay. I figured I could probably use most of it, but I soon realized that the tensioners didn't fit and the shaft and spacers all had to be modified. Once again I decided to make it all from scratch so I purchased a piece of 38mm stainless steel rod for making the axel and spacers. I also designed my own chain tensioners which included some laser-cut stainless steel plates.

Made it all from scratch. Later on I sold the H2 parts.





Machining the outer part of the chain tensioners.





I made these from cast aluminum plate which leaves a bit dull finish, but it will polish up nicely later.





At first I only had a stainless steel sleeve in the nut side tensioner, but later I also added a sleeve to the other one.





The inside of the tensioners are laser-cut stainless steel plate, 3.0mm thick.





Here's the tensioners fitted to the swing arm.





The only thing I didn't make is the nut.



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## zmotorsports (Nov 19, 2015)

P.K. said:


> The only thing I didn't make is the nut.



Why the hell not???  It's not like you didn't know how.

Absolutely beautiful work.  Thank you for sharing.

Mike.


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## mattthemuppet2 (Nov 20, 2015)

damn, that is stunning work! What an inspiration - this is why we have all these tools. Need something, think about it, make it. AND you make it look beautiful


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## mtnlvr (Nov 20, 2015)

Nice work, thanks for sharing.


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## P.K. (Nov 21, 2015)

Here's another bunch of pictures. This time it's all about modifying the swing arm to suit my needs.
The modifications are as follows:

I wanted to use a double needle bearing kit that comes with everything including the seal caps. It's actually an upgrade kit for a Z900. I needed to turn down the ends of the swing arm tubes to fit the seal caps, and since I couldn't put the swing arm in the lathe, I had to do it in the mill.
I wanted treads in the lugs where the shock absorbers are attaches and I used M10 x 1.25 Timeserts for this. The problem was installing the timeserts from the correct side because the swing arm has some welded on support brackets at the shock mounts.
I needed a stopper to prevent the caliper bracket from rotating when braking. I wanted two treaded M8 x 1.25 holes for mounting this stopper (again Timeserts). The challenge here was drilling inside the swing arm.


I made this tool to hold the swing arm on the mill table. Not the most rigid setup but plenty good enough for what I'm doing here.





I like to use a coaxial indicator. I find it easier than using a test indicator and it's accurate enough for most applications. 





I'm not sure what this is called so I'm just gonna call it "outside boring". I have to be careful here because we're running in reverse here and there is a risk of the boring head unscrewing from the arbor. I have loctited the head to the arbor just to be on the safe side.





The finished tube end. I had to go a little bit into the weld on this side of the swing arm.





Now the seal caps fit perfectly on the tube ends.





Here is the needle bearing kit I'm gonna use. The Kawasaki H1 is originally fitted with bronze bushings. This bearing kit is a nice upgrade to improve handling in addition to the much stiffer aluminum swing arm.





Time to add M10 x 1.25 threads to the shock absorber mounting lugs. I wanted to install the inserts (Timesert) from the outside but the welded on support bracket was in the way.





It turnes out the tap drill for the M10 x 1.25 Timeserts is 10.3mm (13/32'') which is perfect hole clearance for an M10 bolt, hence I could drill from the outside through the welded on brackets.
The second lucky coincidence was that the shank for the counter bore tool was 10.25mm so if I could only disassemble the tool I should be able to do the job. Luckily the cross pin attaching the cutting sleeve to the shank was made out of soft steel so I could drill it out.





So now I'm able to counter bore the hole using a temporary pin to drive the cutting sleeve on the shank.





Perfect result and ready for threading. Threading was done from the opposite side. 





And here we have the end result, perfectly square.





The insert sticks out a little bit on the back but that's OK, it doesn't interfere with anything.
It is the end of the insert that expands and locks it in place when driven in using the supplied tool. Since this part of the insert is partially outside the hole, I decided to use Loctite, just in case. 





And now, the holes for the caliper bracket stopper. Here I wanted to use M8 x 1.25 Timeserts. I needed to drill holes inside the swing arm so I bought this cheap wobbly angle gear for use with my drill motor. I tried fitting Timeserts to an aluminum test piece using this angle gear and it was impossible bore straight and with any positional accuracy.
I needed to make a drill guide tool...





... and here it is.





It registers in the axle slot on the swing arm.





The guide is attached and I'm ready to drill 4.0 mm pilot holes. Between each operation I took the drill guide tool back to the mill and modified it.





The drill guide holes have been enlarged in the mill using the tap drill bit form the Timesert kit, and we're ready to drill the swing arm.





I took the drill guide back to the mill and tapped the holes using the tap from the Timesert kit. Now I could use it as a tapping guide on the swing arm.





The holes are finished, perfectly square and perfectly positioned.





The stopper bolted in place using M8 countersunk bolts...





... and there is how the stopper interfaces with the caliper bracket.





The rear end is finished and ready to go on the bike. Once on the bike I will have to check alignment with the front wheel, which hopefully it is spot on. Then I have to align the front and rear sprockets which will be achieved by a combination of turning material off the rear sprocket carrier and spacing out the front sprocket.




And that's it. This is where I'm at now. I will post some more pictures once it's on the bike. Don't know when but probably within a couple of weeks.


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## wrmiller (Nov 21, 2015)

Very nice.


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## Bill Gruby (Nov 21, 2015)

Nice work. I have seen those right angle drill heads around for years and this is the first time I have seen one actually used.

  "Billy G"


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## mattthemuppet2 (Nov 21, 2015)

about running the mill in reverse to turn down the outside of the frame pivot tube - keep your eyes open for a left hand boring bar, then you can run the mill in forward to cut the outside of a piece without worrying about the boring head unscrewing.


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## coolidge (Nov 21, 2015)

P.K. is a steely-eyed missile man! For those who don't know that's the absolute highest of compliments...in NASA!


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## mattthemuppet2 (Nov 22, 2015)

you know i just realised that the thread about lh boring bars that prompted the above comment was written by you


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## P.K. (Nov 22, 2015)

mattthemuppet said:


> you know i just realised that the thread about lh boring bars that prompted the above comment was written by you



Yes, it was when working on the swing arm I realized I needed to start looking for a left hand boring bar for the boring head.
Couldn't find any of the boring head type so I ended up buying a left hand lathe boring bar and cutting it off. I haven't tried it yet though.


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## zmotorsports (Nov 23, 2015)

I'll say it again, absolutely beautiful work.

Mike.


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## Rick Leslie (Nov 23, 2015)

I love the way you've kept the vintage look while incorporating modern mechanics. I had an H1 back in the 80's. It was quick and noisy and fun. Alas, it gave way to parenthood and all that involves. For now I'll live vicariously through your rebuild. Thanks for sharing.


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## MADJACK (Nov 24, 2015)

Awesome work!


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## pegg (Nov 25, 2015)

Beautiful work. You have MANY talents. Thanks for all the details and the photos.


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## Chris H (Nov 26, 2015)

This is exceptional work.  I love that it's on an old Kaw, too.  I've got several older bikes myself, but no H1/H2's.  Yours is beautiful, and tastefully improved.


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## chevydyl (Nov 30, 2015)

Old kawis are known to me to be "muscle bikes" mid to late 70s, they are mean!
Killer job on the build. How about a litter background, how long have you been machining?


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## P.K. (Mar 24, 2016)

Hi again, its been a while.

I just thought I should post some pictures of the finished project. I did the first test ride two days ago and rode 80 miles yesterday.
I'm extremely pleased with the result. This mid seventies bike now handles like a mid nineties bike. It's very stable at high speed and hard cornering feels just right.


I made a chain slider for the swing arm to protect it from the chain. I was made out of UHMW polyethylene which was an interesting experience to machine.





Next I made som aluminum brackets for a set of universal Tarozzi pegs/gear/brake pedals. I had the blanks water cut from 6082-T6 which is very similar to 6061-T6 and one of the most common alloys here in Europe. The brackets are probably a bit "over engineered" with o-rings, grease fittings and press fitted distance sleeves, but hey, it's a hobby.





And finally some pictures of the finished bike taken on my ride yesterday.









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## mattthemuppet2 (Mar 24, 2016)

super cool! That's why we get into this hobby, you've just taken it that step(s) further! That thing must go like stink and now handle as well as it goes


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## Ulma Doctor (Mar 24, 2016)

awesome work.
 i agree with Matt, Super Cool!!!


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