EB1236 - 1973 Honda CB450

Author: Ellaspede   Date Posted:29 November 2023 

EB1236 - 1973 Honda CB450 main image


A cool custom 1973 Honda CB450 would be welcome in almost anyone’s garage. But often 50 year old bikes need lots of TLC and sometimes a new engine… which is where owner Stephen and a Honda CBR500R stepped in to rescue this ride!

We’ll let Stephen start the story… “I’ve been very much a cars, and specifically Porsches, guy my whole life. Everything I know about driving fast I have learnt in my 1970 911, which I've had for 24 years now. But way beyond cars, I love everything Japanese - the food, the art & design, the landscapes, the culture, the history, and of course the JDM tuning and racing. The first car I ever drove was my parents' 1986 Honda Accord. My dad and I watched Formula One religiously from 1986-1991 and every world championship-winning car had a Honda engine... At the same time Wayne Gardner won a world championship on a Honda, followed by Mick Doohan, Casey Stoner, Valentino Rossi and Marc Marquez... So yeah, when I finally ended up getting on a bike myself, there was no decision to be made about which brand I would ride - it had to be Honda. And for this build I actually had to buy two of them!”

“It is a bit complicated, as this is actually two bikes turned into one. The bike whose soul lives on in the frame, tank, side covers and not much else is a 1973 Honda CB450. It was the first bike I ever bought when I first started riding in June 2022. I didn't know anything at all about bikes when I rode it, but I loved it straight away. So much character!”

After our initial inspection we realised the CB450 wasn’t in great shape mechanically. The idea was floated with selling the project on or sourcing a late model Honda twin engine to graft into the frame.

Stephen continues… “I thought I knew the history of the CB450 when I bought it, but this quickly turned out to be inaccurate. I can vividly recall Leo asking me how I managed to ride this bike over mountains down to Byron Bay and back, let alone the short ride from my place across the river to Ellaspede. The engine was kaput with horrendous compression and a cracked top end, which certainly explains how bloody hard it was to start...”

“I originally just wanted to do a really simple cafe racer re-work of the original CB450. Once it became apparent that an engine rebuild was going to cost twice what I paid for the bike (not to mention all the hard to find parts), I started considering alternatives... Ellaspede suggested a donor CBR500R engine could be a smart alternative. My response was - why just buy an engine when I can buy the whole bike for very little money? I got all the suspension, wheels, brakes, electrics and controls of the excellent modern bike."

It wasn’t long after, with Stephens enthusiasm for rescuing the project that a 2013 Honda CBR500R with a few thousand KM’s on the clock rolled into the shop!

Stephen said… “The second bike is a 2013 CBR500R which I bought a few months later specifically as a donor bike for this project. I still remember the brilliant test ride through some beautiful sweeping rural roads - that bike was perfect as it was in the classic Honda tricolour. Only a fool would pull it apart to transplant its bits into an older bike's frame! It (soon) became apparent that this was going to be a lot more than a cosmetic overhaul…"

With the two major pieces of the puzzle (a 1973 CB450 and a 2013 CBR500R) now sitting in the same location, it was time to mix 40 years of Honda development into one modern riding, but still classic inspired custom motorcycle.

The old CB450 engine lump was removed from the frame to test fit the new CBR500R unit. But with so many modern and functional parts on the new CBR, many items began ‘jumping ship’ and making their way into the ‘useable’ pile.

The old frame was completely stripped and getting it rolling again was done with the CBR500R front end slipped on, while the rear was substantially modified to fit the wider CBR swing arm and rear wheel. To keep things classic looking, the single shock mount was cut off the swing arm and new twin shock mounts were welded on either side.

Although the wheels are much more modern looking than the classic spokes and drums, the upgraded front end, better brakes, longer wheelbase and availability of more sticky rubber in the 17” made it all a worth using on the build.

Back to the test fitting of the engine though and as they say… “Close, but no cigar”. The engine would physically fit in the frame, but some key components like the intake, injectors and oil filter had to be removed to do so... not to worry, I’m sure we’ll figure those out. Frame mods ensued to get it bolted in and sprockets lining up. Then the tedious massaging of smaller areas also began with the overall goal of keeping as much of the visual look and feel of the original CB450 cradle frame as possible.

It became apparent there was a clear visual / functional project direction. With the modified CB450 frame holding it all together, the lower half of the bike (engine, wheels, brakes, suspension) would be taking on the CBR500R modern influence, while the top half would keep the classic look and lines with the CB450 tank, seat, headlight, side covers and custom guards.

Key fabrication continued on an intricate airbox for the fuel injection system, modern fuel pump setup, relocated oil filter housing, TDR Moto CBR600R rearset foot peg mountings, mounts for the new KTM SXF radiators and some aftermarket cooling fans.

The usual fabrication was also completed on shortening the rear frame, adding a hoop, seat pan with a quick release latch, custom steel guards front and rear, as well as a full custom stainless 2-into-1 exhaust system and a new chain guard.

There were a large number or new mounts and brackets to be made, especially for fitting items like the new Turbosmart fuel pressure regulator and external fuel pump to feed the injected CBR500R engine. Custom hard lines were also bent up to get out and back from the remote oil filter that is hiding below the swing arm.

When most of the fabrication and key components were mounted, the CBR500R factory loom was laid over the bike to asses what was required, what was being kept and what needed a modification or extension because it was now sitting in a different spot. After that was all stripped back, new wiring was added for all of the aftermarket electrical items that were going onto the bike, before it was all wrapped up in a factory finish sheath.

The CB450 headlight remains in a refurbished state, with a Koso Hawkeye LED tail light and Motogadget pin indicators taking care of the remaining lighting duties. Important information is now displayed via a Daytona Velona 60mm gauge. Daytona was also optioned for the D-mirror bar end mirrors and the ‘GG vintage’ black grips.

A genuine Yoshimura Japan R11 MotoGP muffler slides onto the stainless exhaust for some more modern influence and hangs off a custom mount from the right rear shock. While in the braking department the factory CBR500R Nissin brakes were cleaned, fitted with new pads and now transfer fluid through HEL Performance braided brake lines. YSS supplied the rear shocks and we opted for the classic YSS RD222 Bravo shocks in black and chrome with some custom settings to suit the project and Stephens rider weight.

Boxes of genuine Honda seals, gaskets and bearings were replaced. As you can imagine it was a real mix of CB450 and CBR500R parts on the order sheet. The CBR500R wheels also received a full detail and fresh bearings before they were wrapped up in Pirelli Diablo Rosso II’s measuring 120/70-17 front and 160/60-17 rear.

The original CB450 seats have a classic look which we decided to replicate on the new custom item. With the metal pan already fabricated, we added a few layers of high density comfort foam to give us the right look, albeit a lot slimmer and lower than the original item. Upholstery was care of John Moorhouse Ergo Seats and we opted for black UV rated motorcycle vinyl with the ‘square stitch’ pattern on the top like the original seat had. We also retained the seat strap with some new stainless ends and modified some chrome strip edging for around the sides to continue the original CB450 influence.

Then came time to pick the paint colour and in owner Stephen’s mind it was only ever going to be one choice… “Other than all the black and polished metal bits, there is only one colour on the bike and it is Rothmans racing blue. This colour has a legendary status for being used by both Porsche and Honda racing cars and motorcycles for decades - it was a no-brainer! I wanted to keep the colour very simple in a single block with no graphics or patterns - there is plenty of that to last me a lifetime on my other Ellaspede bike!”

So we dug into the archives of the internet and found that the original ‘Rothmans Blue’ was actually a factory Porsche colour which you see on the tank and side covers here. It’s a lovely mix of dark blue in the shade, but get’s to a decently bright mid blue in direct light which we really like. Finishing off the paint are original inspired Honda logos on the tank in white with a black pinstripe, while the side covers feature the factory badges finished in black, white and chrome.

When we stand back with the bike altogether we think it’s great mix of modern and classic in a pretty tight package. The wheels, exhaust and brakes are begging to be ridden, yet the original lines of the tank, seat and side covers just make you want to stop and stare at it for awhile.

After seeing it, Stephen said… “The classic ‘Universal Japanese Motorcycle’ tank shape and cradle frame has always been the core of the original bike's appeal. I love how these essential elements are still the visual core of the bike where everything else is current-day technology. I also love how Ellaspede have so elegantly managed to fit the water-cooled radiators around the cradle frame and the exhaust headers. And then there's the outrageous Yoshimura carbon exhaust!”

“As ever, making everything look clean and simple is an extremely complicated and laborious process. There is way more thought, craftsmanship and hard work in this bike than anyone would believe.” We were happy to hear that Stephen appreciated all the detailed work that we put into it. A customer that appreciates the build as much as we do is exactly what we like!

Now that it’s finished, safe to say we’re kind of jealous of Stephens plans. He said… “It's a cafe racer not a full-on sports bike, but it's going to do a lot more than pose on James Street. This bike will get me out of bed at 5am for a long ride over the nearby hinterland hills on any day when the weather is decent for many years to come. I’ve had faster bikes than this could ever be, but the enjoyment of getting every last drop of performance out of a bike like this is to me what riding is all about. Certainly right now anyway while I can't legally ride anything crazy fast…"

We know Stephen likes to ride his bikes, so we’ve got no doubt about his plans. Just sounds like we’ll have to take it for a long test ride to the hinterland hills too, if only to ensure it’s 100% ready for Stephen of course.


Albums we listened to during the build of this bike:

1. Samurai Champloo Soundtrack 2. Grimes - Visions 3. Gorillaz - Gorillaz

Photos & Features:

Photos by AJ Moller Photography

As Featured on BikeBound

As Featured in BikeExif Speed Read

Build Pricing & Enquiries:

For build and pricing details or to discuss commissioning a custom motorcycle build of your own please email contact@ellaspede.com

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