collapse

www.dimecitycycles.com

www.townmoto.com


www.restocycle.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.bisonmotorsports.com

www.speedmotoco.com

www.lostapostlejewelry.com

www.cognitomoto.com

www.sparckmoto.com

www.Moto-Madness.com

www.pistonsociety.com

www.steeltowngarage.com

GET DTT UPDATES ON FACEBOOK AND TWITTER

Author Topic: saving a 1980 KZ750 twin  (Read 57128 times)

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #420 on: May 22, 2018, 15:56:18 »
Doc, where did you find the new ones?  I've had the same nagging issue on mine...too rich one day, too lean after the next change...made me so nuts I put her away for a while....

I pulled some out of a set of 29 smoothbores I had sitting around, exact same. Z1 enterprises sells new ones.

Offline MotorbikeBruno

  • DTT SUPPORTER
  • *
  • Posts: 2562
    • Carb cleaning in MN
Re: saving a 1980 KZ750 twin
« Reply #421 on: May 24, 2018, 20:37:28 »
Rock on, I'll see what's in mine currently and switch them up. Thanks for the info. I do love Z1 :)

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #422 on: Jun 15, 2018, 20:53:12 »
The forks were pretty soft, so i decided to rebuild them with new springs and try out the emulators. I dropped the fork lowers off to be powder-coated  and despite my CLEAR INSTRUCTIONS they did not mask off the top of the fork tube. I'm pretty pissed about this because I literally wrote  "NO" where I wanted them to mask. They only masked for powder not the sand blasting.  It doesn't seem like the sand blasting got into the tube too far, but it did peel a bunch of Teflon off the bushing at the top of the tube where the inner tube rubs. There is now quite a bit of play between the fork inner and outer at this location. This coated bushing is not shown in the parts diagram, nor is it mentioned in the service manual. It looks like Racetech has a bushing that has the correct dimensions that may work (36x12x2)  I have another pair of forks that I could use but the caliper mounts have been machined on these for my caliper conversion; something I would rather not do again.

how do I get this bushing out? there is very little lip on the backside, probably about 1mm. Also its in there pretty deep, my seal puller won't reach it.
« Last Edit: Jun 15, 2018, 20:55:51 by doc_rot »

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #423 on: Jun 20, 2018, 03:39:40 »
through some fugly butchery I was able to extract the bushing. I first turned a 37mm washer that was 1/4" thick. Drilled and tapped that  and flatted two edges so it could be passed though and reoriented to catch the bushing. it pulled out easy. The small bolt is to keep the washer from spinning. just waiting on new bushings and the forks can go back together.


Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #425 on: Jun 22, 2018, 06:13:59 »
 I got the new bushing from Race Tech. They fit pretty good. I made a nylon plug to push them in because I thought I was going to have to use my press, but i was able to push them in by hand. This made me a little wary because there is nothing holding in the bushing but friction and it went in pretty easy. I have a set of later model forks that have a spring clip to retain the bushing for this reason. I decided to use a spring loaded center punch to "stake" the lip around the top of the bushing to make it harder to back out. I feel better about this. I finished assembling them with new Race Tech springs and gold valve emulators.

Offline canyoncarver

  • DTT SUPPORTER
  • *
  • Posts: 3522
  • 'hacking is learning'
Re: saving a 1980 KZ750 twin
« Reply #426 on: Jun 22, 2018, 11:57:45 »
Looks good.  Love the Racetech stuff. 
--

YZF750/1000R The Fly
KZ 750 Twin
ZRX 1100
KZ400 The Rabbit
65 Norton, My damn Shovelhead chop, and an 86' FXR
more YZF750R's, the KZ's, a Zephyr750...and the unfinished 75' CB550 cafe.
--

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #427 on: Jun 28, 2018, 05:38:18 »
So much for my quick top end swap.... no wonder it seemed low on power. The right piston pin was seized in the piston and took a puller to remove. Not sure how it started; further inspection required. the small end of the rod is trashed. Luckily i can remove the rods through the oil pan. but since I have to go this deep I'm wondering if i should pull the motor and go through the whole engine? that's a bunch more work i'd rather not do. There didn't seem to be any big chunks in the oil pan, just a little dirt that fell down when i removed the jugs. I just can't seem to get an easy one on the projects lately....

Offline canyoncarver

  • DTT SUPPORTER
  • *
  • Posts: 3522
  • 'hacking is learning'
Re: saving a 1980 KZ750 twin
« Reply #428 on: Jun 28, 2018, 15:11:38 »
Oh man..  That's ugly.  Maybe it's time for the bigger bore and pistons we've been talking about for a few years?
--

YZF750/1000R The Fly
KZ 750 Twin
ZRX 1100
KZ400 The Rabbit
65 Norton, My damn Shovelhead chop, and an 86' FXR
more YZF750R's, the KZ's, a Zephyr750...and the unfinished 75' CB550 cafe.
--

Offline doc_rot

  • DTT BOTM WINNER
  • *
  • DTT SUPPORTER
  • *
  • Posts: 1057
  • Oh the usual... I bowl, I drive around...
Re: saving a 1980 KZ750 twin
« Reply #429 on: Jun 28, 2018, 17:27:05 »
I have 10.5/1 Venolia forged pistons (stock bore), matching cylinder, and a fresh head with a light port and polish, valve job and deck. I was hoping to just swap the top end but it looks like i'm going to have to go deeper.