Our latest build out of the garage is a Honda CB400 Four Café Racer. We love these Honda Four’s it’s no secret. The rider was stoked with his moody looking super sport café racer.
When Will, our client from Victoria got in touch about his Honda CBF400 Four Café Racer and explained the sort of thing he was after it sparked a bit of intrigue for me. He wanted us to build a pretty dark styled café racer, and didn’t really want us to stick with a classic style set.
Usually with our vintage builds they’re punctuated by polished pieces, high wall rims, and colours that lean into a vintage feeling. Take our XS650 signature series or triumph desert sled as example.
This project would take a different direction, with Will wanting most if not all of the bike blacked out. Generally I try to steer clear of the “murdered out” look. Firstly, Its been done to death, and secondly unless executed perfectly it can look cheap and ill thought out. Like someone didn’t even bother stripping it down and hit it with a rattle can of matte black from Bunnings. Will was adamant, and we discussed these points before moving ahead with his dark and moody CB400 Four Café Racer.
The bike had previously had a new seat hoop welded on, but the work wasn’t great and we had to cut out a welded in electrics tray as well. Once we made a few surgical incisions something clicked with the new light weight look of the frame. I got Will on the phone and pitched a monoshock conversion idea to him.
We brace the swing arm, build a triangulated shock mount from some chromoly tube, and make up a top shock mount where the backbone meets the down tubes. This would allow us a super light subframe and an almost floating look to the tail. He agreed, and so we ripped into fabrication. Once the build was done for the monoshock, I got in touch with YSS Australia sent a few pictures and measurements and they made up a custom shock to suit the new suspension.
With grinders and welders running for a few days on the CB400, we had the wheels out for rebuild. New bearings, powder coated hubs and some 18” black excel rims, wrapped in Heidenau Tyres. The front suspension was rebuilt with new fork tubes, springs and pre-load adjusters. So by the time the tail frame was finished we could move ahead with a solid foundation for the rest of the Honda CB400 café racer build.
What we were looking at now was the new monoshock frame, engine, suspension and wheels. Time for some styling. I had a Honda CB400 four café racer tail from Justin at Popbang from a previous project that we decided to use, Dylan set about making mounts for the new tail, electrics tray, and seat. The battery box was fabricated to sit under the swing arm hidden away neatly. Once these parts were laid up the scene was set for the rest of the detailing.
At the riders request we have retained the riser bar mounts, and used a low bend steel 7/8” bar. Kitted out with Accosatto levers, Purpose Built Moto 3 button switches and mirrors, domino throttle and some Biltwell grips. Up front we also have a single 60mm Daytona gauge, with all the electrics operated by our Black Box control module.
Fabrication on the front end included a clean front fender created from our very own DIY fabrication kit. A perfectly shaped aluminium fender, with mounting materials ready to be shaped into whatever your heart desires. A great way to add a unique touch to any build at home.
While the front fender and the 5.75” Flashpoint LED lighting was being mounted on the front, we ripped the engine out and got to work on the rebuild with Purpose Built Performance. The engine build and performance arm of PBM.
Being a super sport the CB400F came from factory with a 6-speed box which helps with a small capacity engine. Our job now was to find those little bits of hidden horsepower in this small but might motor. The engine rebuild always begins with a few tests, tear down and inspection of the motor. No major damage was found but the poor old thing was tired. Low compression and pitting on the valves with a couple of bearings in the bottom end starting to show their age.
The CB400 four café racer was rebuilt top to bottom with performance upgrades including a 466 big bore, new valves, Kibblewhite valve springs, intake and exhaust ported and polished, performance clutch and springs topped off with a dynatek digital ignitionand coils. Generally we would recommend a set of Mikuni RS carbs with these upgrades, however the client requested we retain the stock carbs. These were stripped, thoroughly cleaned and rebuilt. Breathing through a set of DNA performance pod filters.
If you’re looking for more performance again, next steps would be oversize valves, further porting and looking into an upgraded cam which we’re itching to do for one of these mid size Honda fours.
Being a Super Sport, the Honda CB400F Café Racer was supplied with the iconic side swept 4-1 headers. The only problem was they looked like they had been dragged behind a truck all the way from 1975 to 2023. Holes, pitting and dents riddles all through the headers and collector. I really wanted to retain these pipes so we’ve gone through and replaced/repaired any damaged sections of pipe making sure not to change the look of the original styled exhaust. The only change is our Torpedo muffler fitted neatly onto the collector.
With the repairs done the exhaust was sent for black ceramic coat, and the engine pulled for some Gloss Black paint. This is the point I reached out to Nathan from Livin Loco. Because of previous conversations with Will I knew he wanted the colour palette to be dark, so you can imagine his surprise when I suggested purple…. It took a little convincing and once Nathan and I got together and discussed the idea got will excited. We would use a Nissan GTR Purple, but mix it with some black to further darken the paint.
The result is about as deep a purple as you can imagine, only giving its full colour away under bright lighting. Detailed with a few select pieces of pinstriping, and logo details that you’d miss if you weren’t looking. As the bike was being pieced together for its first fire the seat went to Timeless Autotrim for some leather work. A seemingly simple design with a few nice intricacies worked in to add some detail.
The start up procedure and first rides on this bike we’re flawless. Having the engine built in house and run through our stringent commissioning checks when an engine fires first time every time its no surprise. Every time it happens through I’m reminded why I love these air cooled 4 cylinder engines. The intake noise from the carbs, and that hum from the 4-1 is hard to beat.
Check out our YouTube video for some ride clips but this one was fun, a late afternoon up a twisty mountain road not far from our workshop, after a few local run in rides and some adjustments the CB400 four was ready to stretch its legs. Tight corners, some nice inclines and banked turns makes for a great experience. The engine laying down some great power up in the rev range, the suspension working perfectly and the brand new 1975 motorcycle completely in sync. The upgrades to the brakes are a welcome advantage when barrelling toward a corner making sure you can pull up and power on when needed. Its not the fastest bike on the hill but if you’re not having fun on this thing between 60 and 120kms/hr that’s your fault not the Honda’s.
If you’d like more details on our Honda Engine rebuilds, this bike in particular or a complete custom build for yourself please get in touch via email. Thanks for taking the time, ride safe.
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Purpose Built Moto is home for unique custom motorcycle builds. We offer a unique motorcycle customizing experience in the heart of the Gold Coast.
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Hey,
first of all, beautiful build. Love what you’re doing on those lovely Honda.
As a owner of a 400f myself, I’d love to know more about the Tokico breaks.
Could you tell me which one you build in and if you did a custom mounting bracket?
Thanks and keep on builiding these lovely bikes.
Cheers from Germany