Honda P50 Custom Restoration - Classic Motorbikes

Fancy a ‘P’? – Peculiar Preservation

Whilst we don’t expect everyone to feel ‘inspired’ by our latest creation, give it a few lines and I will try to explain why this strange motorized cycle has consumed the last few months of our lives. Firstly, the P50 (otherwise known as the P25) was a decision Honda may well have regretted taking; the model ran for just two years and now few fully original versions remain. It hit the showrooms in late 1966 and came with one feature that mainstream manufacturers have not repeated since; the engine is fitted inside the rear wheel. A decade prior to the Honda, it was BSA that offered an option for powering one’s push bike and for just 25 of your finest British pounds a new rear wheel with a 2-stroke 35cc motor attached was supplied; the buyer swopped the tyre and hit the road. Honda went one further with their super reliable 49cc four stroke OHC installed within the rear wheel, which came complete with frame, seats and even a basket and lights should you choose. Yes, a complete machine that offered 1.2 hp that didn’t require fuel and oil mix for 49 ¾ guineas or £52-4s 9d in 1967.

The Motor Wheel

The idea is nothing new, especially on two wheels. The first Singer motor vehicle produced included a Perks & Birch 222cc four stroke unit as part of the rear wheel in 1900. Edwin Perch and Frank Birch unveiled their ‘motor wheel’ design the previous year and was immediately taken ‘on board’ by Singer Cycles, as were the inventors themselves, joining the Singer brand as production of two models began. A tricycle arrived just one year later and moved the power plant to the front wheel, whilst the original bicycle version featured the engine in the rear. Causing something of a sensation at the Motor Shows that marked the start of a new century; the dawn of motoring especially in the UK

One journalist covering the events at the time made headlines in National publications when he reported… ‘The Singer Cycle Company Limited, have, however, made a departure in motor cycles! The engine, of the internal combustion type, using petroleum spirit, the carburettor, speed gearing and ignition device, are all contained in the driving wheel of the bicycle, or in the front wheel of the tricycle, and the arrangement is not nearly so unsightly as in most motor cycles.

The motor is capable of developing about 2 horse-power; it is air cooled and is provided with the Simms-Bosch magneto-electric ignition. The cycle wheel is composed of two aluminium cages, which run on all bearings on either side of the motor, and are bolted together near the rim. The rim is of steel, and is fitted with a pneumatic tire. the crank shaft of the motor lies below the centre of the driving axle, and carries a spur wheel, which gears into an internal toothed wheel fixed to one of the aluminium cages. Only one regulating lever is fitted, and this is on the handle-bar of the cycle. In one position this lever reduces the compression in the cylinder for starting, and in the opposite position it controls the explosive mixture. The machine only differs from an ordinary bicycle as regards the back wheel, the rear forks, and the increased width between the cranks; its weight is about 1 cwt. The carburettor is of special construction, and gives a constant mixture of air and vapour, thus dispensing with the regulating devices. Its design is such that the spirit will not spill if the machine is overturned, and as the explosions are caused by an electric spark …. there is little danger of fire’.

All sounds familiar but it’s worth remembering the motorcycle was relatively new for the period, whilst the motor-wheel was completely unique and evidently rather uncomfortable to ride; but enjoyed impressive performance. Taking part in several competitive hill-climb events it took the gold medal in Dublin. In 1901 with Edwin Perks aboard, the Singer was the powered bike to climb the Crystal Palace Hill without pedalling at the Automobile Club trials, following this victory it was ridden all the way back to Coventry. In July 1902 Perks went on to win gold in both the 1.75hp and 2.75hp classes at the Catford Cycling Club hill climbing competition ascending Westerham Hill in Kent. To silence doubters in the crowd who thought some form of cheating was afoot, he then removed the chain from his machine and rode up the hill again waving it in his hand, “to the astonishment of the thousands of people who lined the course.” On another demonstration run in 1902, a Singer tricycle fitted with a wicker basket to the rear pulled a combined weight of 50 stone, up a 1-in-8 hill, 300 yards long.

Alternate Engine In-Wheel Motorcycles

The Megola from Germany was by far the most striking ‘in-wheel’ powered contraption fitting a five-cylinder Rotary unit (much like a piston aircraft) into the front wheel in 1923; as with a propeller you were required to spin the wheel to start it! Cyclemaster produced a 25cc rear wheel powered bike in 1950, these came from the German DKW concern and were assembled by EMI at their factory in Hayes Middlesex. Variants were also produced in Switzerland, Holland and copied by the Chinese (yep they were doing it 70 years ago) and this was called the Flying Pigeon. The Cyclemaster option much like the BSA could feature on any cycle and well-known names like Briggs & Stratton or Raleigh offered their versions.

Personal Passion

This interest in early ‘Peds’ reared its ugly head when the chance arose to acquire a ‘Little Honda’ P50 with its engine in the rear wheel; courtesy of motorbike-breakers in Peterborough. Another soon followed, both incomplete and one in very poor condition; then much searching and bartering produced a totally original 2 owner ex-museum machine from 1967; this now enjoys pride of place within my workshop. Only requiring a day of detailing it remains unaltered from new; although it will certainly be ridden and presented to anyone who shows even a glimmer of interest. The P50 offers a unique riding experience with the weight of the motor-wheel barely noticeable on right hand bends but on left handers its sole aim is to ensure both bike and rider meet the tarmac. With a lot of care and a little practice the ‘Little Honda’ is mastered and is a joy to ride right up to 25mph when it feels like a large anchor has been thrown off the back; but having a complete working version gave me an idea. The purchase freed up my pair of bitsa’s that are both largely incomplete, don’t run and neither enjoy any paper work plus the DVLA shows no records to re-register. Therefore, we decided to rebuild the remains in a unique fashion; a display piece is the best description.

Doing a Derny

Reading stories of Edwardian era motorbike races at Brooklands combined with the 1920s wooden ‘Murderdrome’ stadiums across America led to an idea. Build a combination of Velodrome bicycle racers pacemaker or Derny and the mule required to ‘tow start’ the motorised daredevil racers from a century past. Competition large capacity bikes enjoyed no brakes or clutch, thus were usually dragged to a starting speed and released to do battle, whether it be in Lagoon Motordrome Cincinnati or Brooklands in Weybridge, Surrey. Minimalistic, light and available to hold a pace the Derny idea stuck, our biggest task was to make an old bike appear older still. We had the basic ingredients with little in the way of suspension components plus the engine in wheel design that gave our unique project visual age.

Our inventory included two frames (one with a large hole in) plus a complete engine (almost) with four rusty wheels. The handlebars and levers would not be required as the Edwardian style Dutch bars seemed far more in keeping with the theme; this idea would present several problems later in the build. Initial tasks were to strip and prepare the frame, luckily the chosen item was solid and responded well to a week of paint stripping followed by a few coats of primer.

Designing ‘On the Hoof’

Deciding to make it up as we went along may have led to many options being dropped or added mid-build but with little more than some grainy black and white images to inspire, it seemed the way to go. A 19-inch front wheel and the original 17 rear maybe considered unusual but with an oversize rear tyre we hoped to balance the stance of our creation. We removed the engine from the rear wheel, a fairly straight forward task, but not something Honda promoted within the owner’s manual, even replacing the inner tube was carried out with the ‘wheel in situ’. Offering the rims some age required a trip to the blasters, plenty of masking tape with dark grey finish whilst the huge alloy hub just screamed polish me! The ignition cover with HONDA imprinted had endured a scrape or two in its life so received a gloss black finish post repair, this would match the round exhaust silencer.

The front suspension was designed for the Honda P50 and would run through most of the marques mopeds until the late seventies; small springs offering minimal cushioning via a cantilever. The nylon bushes were replaced and all finished in gloss black. Propulsion can be enjoyed in the same way the average bicycle operates but once the lever at the rear of the engine is engaged more effort is necessary as this turns over the 49cc piston and hopefully fires it into life. Our engine turned over but the rear sprocket was minus a tooth, not a good sign as the hub itself is rather a complicated arrangement but we scavenged enough parts together and rebuilt. The exhaust pipe exits the engine under the nearside before traveling forwards and bending around the rear wheel, then exits to a silencer; a circular chrome plated design that is always the first thing to hit the ground should the worst occur. Ours had, and being a sealed unit took a whole afternoon to prise open before offering a chance to beat the dents out followed by a trip to have the remaining chrome removed.

The original fuel tank behind the seat resembled a cullender which wasn’t an issue as part of the design was to weld in a steel bar (from an unloved BMX frame) and fit a bespoke tank; this arrived from somewhere in the far east I cannot pronounce. With a contrasting colour to the frame I sprayed the original air filter covers (under the seat) to match the tank and flywheel cover, we then ran a braided fuel direct to the carb; no point hiding it, best to make a feature. The BMX bar slotted in well and filler finished off the addition before our complete frame enjoyed several coats of ‘Ye Olde English White’ with lacquer. A pig skin tan saddle with large springs came via a very ‘slow boat from China’ whilst a pair of orange fork gaiters received a mix of matt black and Wilko’s £1 ‘tester’ pot in peach to produce a worn leather appearance hiding the steering and seat stems; all very arty.

Will it Start?

Parts arrived from our supplier known as ‘Mopedland’ and included new tyres and a bicycle chain, which would offer enough length to fit over the strange but original tensioner arrangement; the chain is only used to turn the engine over, once running it becomes redundant. Also, a company called ‘Petrolscooter’ supplied oversized throttle cable and grips with lever from a mini-bike to match. The original units are part of the 1967 handlebars and not the Edwardian look we were after.

This Honda’s original bars were produced as one single unit with the stem and levers all welded into place, so to connect the 22mm Dutch bars with an original stem we utilised our angle grinder and one solid two-way knuckle from a mountain bike. With the flywheel removed the points could be adjusted and we had a strong but erratic spark; soon it became apparent the coil/condenser unit was failing. Sticking with the trusted philosophy ‘it’s a Honda so will start’ even after decades of remaining dormant it did just that; although its sounded terrible and conked out within seconds. After cobbling together another condenser with bodged up wiring things improved, not perfect but she revved up, began to smoke and smelt bad…all good signs. A mighty 0.7 litres of fresh oil and new plug helps, whilst the missing original air filter housing is substituted with a breather filter resized to fit; looks good but too much air is another obstacle we will need to resolve. We had to source a non-OE decompressor lever, this allows easier starting and also stops the motor; surprisingly few UK suppliers carry the 22mm size with barrel cable fitting.

The big decision now is what to do with it? Financially it didn’t ‘break the bank’ but the man hours invested would certainly run into weeks and we still have a way to go. Improving performance of the venerable P50 will no doubt be limited but with its ability to attract attention at classic events our ‘evolving’ version proves to be a winner. When it chooses to start it is not the most enjoyable thing to ride, although every man and his dog want to sample just how uncomfortable a machine can be. Saying that, it may well inspire some interior or shop front designer; we thought it would work in an upmarket cycle establishment doing its ‘Derny’ duties with Edwardian attired manikin leading the way. However, we enjoyed the adventure, low cost and not too complicated but our next rusty relic awaits some attention, although I will be surprised if it creates the head scratching this unique Honda does.