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TOPIC: Saving a '81 KZ750-E

Saving a '81 KZ750-E 30 Apr 2019 11:45 #803103

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I'm new to this forum, and really glad I found it! A lot of good information and resources. I had a friend gift me a 1981 KZ750-E last year that has been sitting outside in southern California for the last 28 years. He was the original owner and logged 34K miles on it before parking it in his back yard. The sun has taken it's toll on the bike, and the insects decided it was a great place to start a commune. My plans for this bike is a resto-mod, with a vintage Superbike theme. I will be using the front end from a 2005 Honda CBR600-RR. After modifying the steering stem, I was able to press the KZ stem into the Honda lower triple clamp. The front end will now bolt up to the KZ frame using stock sized bearings.

Currently I have the bike down to the frame, and the top end of the motor is at the machine shop. Several valves were stuck, so a complete cylinder head rebuild was in order. I was referred to RTC Engineering in Florida during my search for new pistons and rings, and they had a set of 10.5:1 racing pistons left on their "old stock" shelf. This was a stroke of luck, since I was having trouble locating pistons that were 67 mm in diameter. I am debating on leaving the bottom end intact and just going with the top end rebuild.

I am working on adding a swing arm brace to the stock swing arm. The brace will be 1.50" dia. x .090" wall tubing. I made a weld fixture to keep the swing arm straight. I have the tubing bent, but have not started trimming it to fit yet.
'81 KZ-750 E1
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Saving a '81 KZ750-E 30 Apr 2019 17:12 #803120

  • riturbo
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Welcome B)
Gpz 750 turbo The one I ride
Gpz 750 turbo Not finished
Gpz 750 turbo Not started
Gpz 550 1981
Gpz 550 1983
Bunch of other junk
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Saving a '81 KZ750-E 30 Apr 2019 19:35 #803127

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Welcome to the forum! I'm always amazed at the fact that some folks basically abandon their bikes and let them sit unused for decades. A guy close to my house had a Honda chained to a tree for about 25 years, but eventually he moved and I guess sold the bike. I'm glad you're going to bring that KZ back to life! Ed
1977 KZ650-C1 Original Owner - Stock (with additional invisible FIAMM horn)
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Saving a '81 KZ750-E 01 May 2019 16:58 #803167

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Here is the weld fixture for the rear swing arm. 1/4" steel plate, with 3/8" thick angles

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'81 KZ-750 E1
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Saving a '81 KZ750-E 04 May 2019 17:52 #803341

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I just got the cylinder head and cylinders back from the machine shop! All new valves, guides, seals, seats machined, mating surfaces trued, rings gapped. etc. Now I just need to decide on going with the used bottom end, or jumping all in and splitting the cases and see how it is. I haven't researched the availability of internal engine parts yet.
'81 KZ-750 E1

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Saving a '81 KZ750-E 05 May 2019 09:55 #803366

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Started to fab the swing arm brace this weekend. Coping the ends to get a good fit for welding will be a bit tricky, and I only have one tube bend to work with. So I am using paper towel rolls and toilet paper rolls as templates. A lot cheaper to screw those up first, then when I get it how I like it I will trace the shape onto the tube.
'81 KZ-750 E1
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Saving a '81 KZ750-E 05 May 2019 10:22 #803367

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Welcome. Another KZ saved and I like where you are going with it...
Jim
Atlanta, GA
2016 Yamaha FJR1300ES
1982 GPz750 R1
1974 Kawasaki H1
1976 Kawasaki KZ400
1979 Yamaha XS650 cafe'
2001 KZ1000P
2001 Yamaha YZ426
1981 Honda XR200 stroked in an '89 CR125 chassis
1965 Mustang
1967 Triumph GT6
1976 Bronco
"If you didn't build it, it's not really yours"
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Saving a '81 KZ750-E 08 May 2019 12:01 #803522

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Just finished fitting all the brace tubes, and it's ready for tack welds.
'81 KZ-750 E1
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Saving a '81 KZ750-E 08 May 2019 12:42 #803523

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That brace turns out really nice :cheer:

/A

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Saving a '81 KZ750-E 10 May 2019 06:40 #803635

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Following! Nice swingarm...
Kawasaki KZ 750/4 LTD 1981
Kawasaki KLR 650 2011
Argentina - Buenos Aires

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Saving a '81 KZ750-E 11 May 2019 23:00 #803702

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subscribed!

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Saving a '81 KZ750-E 15 May 2019 11:14 #803924

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When I started to fab this swing arm brace, I had to make some assumptions. The main one was to follow the profile and width of the original swing arm. All I had to go off of was pictures from the side on existing bikes. In the back of my mind I was wondering if there would be enough clearance for the chain. Well, I got it tacked together, and fitted it to the frame yesterday. Total failure! Glad I only tack welded it together, because now I have to cut it all apart and start over again. I am thinking the width needs to increase at least two inches to create the space needed for the chain to clear. Unfortunately my tube bender will not go past 135 degrees, so I had a friend bend the piece I used to mock this brace up. I will need to split it on center line, add a piece, and weld it back together again. If it comes out looking like Frankenstein I will at least have a better mock up to start a new tube bend. The other issue I did not get right is the section that joins the brace tube to the original swing arm. I went with perpendicular to the swing arm, but it needs to be angled back toward the rear axle at least 10 degrees to clear the frame tube (see photo). Back to cutting and grinding! Revision B coming up in a few weeks...
'81 KZ-750 E1
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Saving a '81 KZ750-E 07 Jun 2019 10:17 #805307

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Finally correcting my mistakes. Three inches wider near the swingarm pivot, and one and a half inches farther away from the pivot. Chain and frame clearances look much better.
'81 KZ-750 E1
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Saving a '81 KZ750-E 07 Jun 2019 10:49 #805308

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Last tubes fitted.
'81 KZ-750 E1
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Saving a '81 KZ750-E 11 Aug 2019 14:07 #809043

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Been really distracted last couple of months, so haven't had much progress. Today I finally got some time to do the first mock up of the suspension. Seeing the wheels on the frame is oddly motivating! The frame, swing arm, and kickstand will be headed to blast and powdercoat soon. Really happy to have moved into my new shop!
'81 KZ-750 E1
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Saving a '81 KZ750-E 15 Sep 2019 11:32 #810882

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I had a real hard time getting the swing arm pivot bearings out. When trying to drive them out with a punch, the inner cages got destroyed on one side, leaving an even smaller edge to catch. I was able to get one side out, but for the other side I ended up purchasing a steel round bar, 1-1/16" in diameter, to press the outter races out. Good plan on paper, but the bearing bores were not machined on center of the tube. Even though the bar was smaller than the bearing bore, it would not go through with out using my 20 ton shop press. I finally succeeded, and with some more dressing down the swing arm will be ready for powder coat. The inner sleeve is worn beyond use, but I found All Balls Racing sells a sleeve almost the same size. It is .002" larger on the OD, so I may need to have it precision ground. Anyone know where to get an original stock sleeve?
'81 KZ-750 E1

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Saving a '81 KZ750-E 15 Sep 2019 12:47 #810889

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Do you have the dimensions of the sleeve you need OD/ID/length in metric mm?
Your needle bearing typ is Hk2216 = OD 28 mm, ID = 22 mm, length = 16 mm (you need 2 needle bearings on each side).

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Saving a '81 KZ750-E 15 Sep 2019 14:03 #810892

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The same sleeve was used on the later 650's but unfortunately, it's been discontinued by Kawasaki and ebay doesn't have anything.

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Saving a '81 KZ750-E 15 Sep 2019 14:32 #810894

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Saving a '81 KZ750-E 15 Sep 2019 18:33 #810904

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The stock sleeve OD measures 21.94 mm at a spot without bearing contact. With a 22 mm OD sleeve, I would need to have it ground to fit in the stock bearings.
'81 KZ-750 E1

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Last edit: by Skidmark.
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