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Author Topic: Project CB690 (KTM 690 engine in a CB550f frame)  (Read 8872 times)

Offline goodoltup

  • Posts: 53
    • Personal and Work Website
Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #80 on: Aug 22, 2018, 17:28:22 »
Started making the swingarm pivot mounts on the manual lathe at work. The finish came out a little manky, but that is due mainly to speeds and feeds. These will be welded into the plates and will use the stock KTM swingarm hardware to link up the engine, swingarm, and frame. The last picture shows the threading operation. I also have to fab up a tool to torque the swingarm pivot insert, more on that later.

Offline goodoltup

  • Posts: 53
    • Personal and Work Website
Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #81 on: Aug 22, 2018, 17:31:11 »
Slow going on the frame modifications. All those factory welds have to be ground down and the tubes prepped for welding. I've used a combination of an air-hacksaw, angle grinder, and small pnuematic grinder with sanding discs. Not looking forward to having to finish this up.

Offline goodoltup

  • Posts: 53
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #82 on: Aug 28, 2018, 09:53:20 »
A drawing of the swingarm pivot that I machined. Inspection of the part showed that I got within 0.05 mm on most dimensions, some bang on, with the exception being the depth of the bore. That was way out. I used a stop on the lathe to gauge depth but something wasn't right, ended up being out by 0.8 mm. For this application it is not important, just need more practice on the lathe.

Offline goodoltup

  • Posts: 53
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #83 on: Aug 30, 2018, 13:41:41 »
This tool my colleague made for me on the mill, to torque the swingarm adjuster nuts that are located in the pivot. It has a 17mm hex.


Offline goodoltup

  • Posts: 53
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #85 on: Sep 23, 2018, 11:56:31 »
It's looking good. I have assembled the swingarm pivot components and will start welding soon. The plates have to be fettled with the grinder until they fit perfectly, and v-grooved. Also the front motor mount is complete. The spacers are made of mild steel, I may weld them to the mount plates for extra rigidity. Also those bolts will be shortened in the lathe. They were chosen to give the proper amount of unthreaded area.
« Last Edit: Sep 23, 2018, 11:59:08 by goodoltup »

Offline goodoltup

  • Posts: 53
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #86 on: Sep 23, 2018, 13:02:41 »
Have received the frame tube from Pipecraft. I paid 90 for two, and they sent four. They I haven't measured them, maybe two of them are close but not conforming to drawing. I don't really need four, but maybe I can use them for weld trials.

Offline goodoltup

  • Posts: 53
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #87 on: Oct 10, 2018, 03:46:56 »
Sneak peak. I ordered new aftermarket sidecovers and seat for purposes of mocking up. The sideplates have been tacked in only at this stage.

Offline Popeye SXM

  • Posts: 146
  • Also used for MX
Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #88 on: Oct 10, 2018, 13:30:28 »
Oh yes! Great rear end  :)

Offline goodoltup

  • Posts: 53
    • Personal and Work Website
Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #89 on: Nov 04, 2018, 15:19:10 »
Time to choose my rear shocks. I would like to have the shocks in hand for mocking up the mounts that will be welded to the swingarm. Not being sure what length shock to buy I made a calculator in Matlab where I inputed frame dimensions and proposed shock and fork lengths, and get the resulting rake, trail, swingarm angle, shock angle, and seat height. I had targets for all 5, so I fiddled with the front fork length and shock length until everything was satisfied. I will start with a 320mm shock, taking into account the height of the shock mounts themselves. This is with shortening the front forks about 50mm. This can all serve as a basis, and once the bike is rolling I can adjust the front fork length with springs and spacers, and the rear shocks are +-10mm adjustable, too, so I can fine tune it. I could have done this in 2D cad, but this was a fun project. Screenshot 3 shows the program output.