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Author Topic: Project CB690 (KTM 690 engine in a CB550f frame)  (Read 17361 times)

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #60 on: Jun 01, 2018, 17:18:44 »
Work has begun on the frame jig. I have received several metres of 2x3" steel box section tube, which will form the frame of the jig. Instead of clamping it all together like some frame jig kits I have seen, I will weld it. One problem I needed to solve was making the steering neck cones for the jig. I decided that instead of making cones I could use the existing bearing cups. First I make some discs on the lathe. The bearing cups were then ground down to allow a light fit in the steering neck cups. The bearing cups were then tig welded to the discs. The third picture shows the welded assembly in the steering head. The welded assembly then went back on the lathe to have a 16mm hole drilled concentric to the bearing cups.

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #61 on: Jun 01, 2018, 17:25:30 »
I used the mill at work to get the required angle on a small section of the tubing, and to drill the 16mm holes through both sides. The small bit was then welded to the frame jog upright, and 16mm threaded rod used to make the steering head holder. I don't have a lot of great pictures of this process, but hopefully from the last picture you can see the bit that was in the mill.

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #62 on: Jun 01, 2018, 17:28:43 »
And the garage is looking pretty good! Soon the frame will be in the jig and the work of putting the motor in can begin.

Offline stubsryan

  • Posts: 88
Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #63 on: Jun 03, 2018, 09:26:42 »
Sweet project mate. Iím really looking forward to seeing how this one pans out. Keep up the good work


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Offline CrabsAndCylinders

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #64 on: Jun 03, 2018, 16:20:55 »
Very nice workshop!
Lighter, Quicker, Faster.
ZX-14, 900F x 2, 1100F, R100, CBR600, SR500, GT500, RZ350, KZ1000 x 2, Moto Guzzi Lemans lll, CBX550, RD 350, 750 SOHC police special, RG250, TL1000R, GT750, KTM Super Duke 1290 R, Harris/Z-1, Norton 750 Commando, Green 77 KZ650

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #65 on: Jun 09, 2018, 17:21:17 »
This is my current welding setup. I ran a higher amperage line to a socket that is only used for the compressor and the welded. Only one at a time can be used, but that really should not be a concern. The welder has been doing great, I have no problems with it at all. It's a lovely piece of kit, cheap and cheerful.

Offline goodoltup

  • Posts: 111
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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #66 on: Jun 09, 2018, 17:30:56 »
Ok this is what it's all about. The frame is in the jig. I used a digital inclinometer to ensure that all the tubes were square to each other and that the headstock was set at the same angle as the stock KTM. This was really just for mockup, the real headstock angle will be set with the shock length once the frame is released from the jig. For the time being the most important thing is that the headlock is perpendicular to the jig, and that the frame is centred in the jig. Once all the measurements had been taken, the frame was tacked on the upright that is under the frame cross member. Next I will make a holder for the engine so it can be positioned in the frame while being kept in the same plane as the headstock. Then it can be positioned and the motor mounts mocked up.

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #67 on: Jun 18, 2018, 18:17:04 »
Here I've made an engine mount out of some tube and remnants of the KTM skid plate. This allowed me to position the motor in one plane, moving it around until it worked. There were several compromises to make, namely if the motor was too high the injector interfered with the frame, and if it was too low the chain would rub on the frame cross member. A pretty good solution was found, in that the injector could be rotated a few degrees to allow the necessary injector clearance, and the motor could be positioned at max height and provide good chain clearance. Still necessitates the replacing of a frame tube, but that I was prepared for that, see a few posts ago where we priced up a precision bent tube.

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #68 on: Jun 18, 2018, 18:19:57 »
Mockup of the tube and swingarm plate. I know the plate is big. But it is the compromise I am comfortable with.

Offline goodoltup

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Re: Project CB690 (KTM 690 engine in a CB550f frame)
« Reply #69 on: Jun 18, 2018, 18:24:50 »
This may be a big decision here, but I think I can use the original KTM swingarm. Think of the work it would save! I wouldn't have to manufacture a swingarm from scratch. The bearings would work, the rear axle would fit, it looks cool. Only problem is that it taking into account the 75mm the swingarm pivot is moved forward, the KTM swingarm would add 80mm to the wheelbase. And, of course, it's mono shock and not dual shock. I believe that I can have some clevises welded on (I won't do it) and I can machine off the boss for the mono shock, that should be trivial. The rear calliper would have to be mounted differently because it would interfere with the shocks, but again that is ok. I think I can live with this.