Just a little tip for people contemplating doing an Upsidedown fork swap in their CB:
A USD fork of a KTM 125/390 Duke or RC (Duke has handle bar mounts, RC has clip-ons) will fit without any hard work, and relatively low cost (I got a complete fork with yokes, handlebar clamps and front wheel axle for 300 euro).
- bottom bearing standard CB350f / CB400/4
- Top bearing ID 30 instead of 26mm
- Best bit: stem length is spot on.
- Even the steering angle stoppers fit.
- CB350f fork is 69cm long (wheel axle to top-cap), when parked on the main stand.
- KTM fork is 72 cm long, when parked on the jiffy. KTM uses a smaller wheel of course.
Fitting as follows: The Allballs CB stembearing kit comes with 2 spacers, combined they are 7mm thick. Exactly what is needed to clear the KTM bottom yoke and the CB frame.
Top bearing: fit as standard KTM.
Keep in mind:
- I have not yet checked tank clearance.
- This fork set-up has a single brake disc only.
- offset of the fork is approx. 40mm. CB350f is approx. 60mm, so trail is affected. Don't know yet what this will do with handling, but I guess this is similar to most USD fork swaps.
Big thanks to allballs for providing their conversion tool (
https://www.allballsracing.com/forkconversion/), and the KTM Duke rider who helped me measure the KTM fork before putting the money down.