CB400 Track Hack

[Aussieflyer]

Hello again.  Gosh it's been a very long time since I started this project, almost eight years, however now I have progress that's worthy of an update to this post ...

Finally the bike and I were ready for a track day.  I trailered the little CB400 to Philip Island in late November 2025 where it, and I, were slow in comparison to many of the other faster machines and riders however the bike performed very well.  I was so pleased with the way it behaved and felt that, for most of my drive home, I pondered the potential to convert the bike back to road legal and re-register it for road use.  Some research of our vehicle road registration requirements pertaining to previously crashed motorcycles confirmed exactly what was required to re-register the bike.  In Victoria Australia select repaired vehicles 15 years or older do not require engineering certificates and are allowed limited modifications including non-original exhaust systems.  I needed to fit all the usual equipment including lights, rear mud guards with reflector, turn indicators, horn, quiet exhaust system, rearview mirrors, road compliant tyres, and have the vehicle assessed by a registered tester to confirm road worthy condition. 

Following several weeks of online shopping and many hours tinkering in the workshop where a smaller rear subframe was fabricated, new lights / indicators / horns / mirrors were fitted, and the wiring loom was modified with quick release waterproof connectors I had the machine ready for assessment.  The replacement rear subframe was required to provide for secure attachment of the rear lights and mudguard extension.  A neat feature of the rebuild is that all the road legal stuff (lights etc. registration plate, mud guard) are simply unplugged and by undoing two bolts can be removed in one assembly.  The headlight and front indicators are removed with quick release connectors and undoing two nuts and another two screws, it's 'track ready' in 15-20 minutes.  This little CB400 will serve it's original intended purpose as a track hack for my son and I, PLUS give us enjoyment on the local twisty roads. 

The bike has spent only one week being road ridden shaking down the rebuild.  I've been fortunate to have no mechanical issues, just some tweaking of the rider ergonomics and the front suspension to make it more comfortable.  I built the forks and had the rear shocks re-valved by a professional aiming for track application however the local roads are rough and I need a more compliant ride.  Removing, tuning and refitting the Racetech emulators was quick and easy, the front now feels perfect.  The rear will likely take a thousand or two kilometers to fully settle in then I'll work out what, if any, changes need to be made.  Immediate next steps include replacing the damaged instrument assembly with a new one, and changing from the low-set clipons to either a set of high rise clipons or low-rise superbike handlebars.  I still want the longer reach to the bars but not the low height relative to the seat and foot pegs.  When rider ergonomics are finalised the second last job will be to shorten the braided front brake lines for a neater look.  The last job will be quite some time away, probably during our winter season, when I'll investigate what's involved in creating a watertight compartment in the single seat tail unit with a lockable access door.
When it's all finished I will post a completed project picture but for now here's a few photos.

Amongst some heavy weight iron at the local biker bar:












Subframe removed:


New subframe components:


Subframe fitted: