The Board Tracker
Way back in 7th grade, whilst working on my very first red go-kart, my mother showed me an up and coming company in Santa Cruz CA called “Vintage Electric Bikes.” I read through their styling inspiration. It had a very distinct look. The smooth bends and fast looking geometry made it something I immediately wanted. The inspiration for those bike were of the Board Track motorcycles of the early 1900’s. It was a short lived sport, but popular enough to have birthed several bikes each with their own style. I eventually settled on a Harley Davidson style Bike, and decided to use a Wisconsin-built Briggs and Stratton engine to accompany the Wisconsin-inspired bike.
The Goal
To the right is the very bike I fell in love with. The sleek curves and fast geometry, mixed with the no nonsense use of space, primarily being wheels and its engine drove the form that would influence this bike. Of course in my rendition, there would be brakes and a clutch of some sort, the goal being to ride this on the street.
https://www.heroesmotors.com/products/1920-harley-davidson-board-track-racer
The Frame
To save time as well as headache from bike frame geometry, it was decided that cruiser bike frame would be the ideal starting platform. “Save time” is ironic as this became my longest spanning project. The frame’s steel construction allowed welding directly to it, and the prominent curve at the top best matches that of the original bike. To accommodate the gas tank, the existing curved tubes along side the top tube had to be cut, and replaced with a straight tube. This allowed for mounts to be welded to hold the gas tank on later.
Above shows all the unneeded material removed to make space for the engine. Due to the engine having a relatively wide square base, the engine was forced to be higher than preferred. If this were to be redone in the future, I would likely have chosen an engine with more traditional side mounts like an actual motorcycle engine. Despite these drawbacks, the engine still fits, and all is good.
Gears and Stuff
The big “pizzazz” of this bike is the starting system. The pedals were connected to the jackshaft with a freewheel to enable an easier engine starting procedure. In addition to this easy starting system, the primary drive belt can be taken off and the bike can be pedaled with relatively little resistance in the event the gas tank goes empty. In addition to easier pedaling, this made the bike legally a moped, which meant it needed no registration. As it turned out, the primary drive belt constantly slipped. In a second revision, I removed the pedal start and the belt system was replaced with a torque converter (CVT) for better and smoother acceleration. The rear sprocket, attached using the brake rotor mounting holes on the bike wheel eventually received a 60 tooth sprocket instead of the 36 tooth shown.
To the left is a better look at the drive system. The order of components from left to right is drive pulley, centrifugal clutch, bearing blocks and finally freewheel. This allowed the bike to be started with the pedals, but once started, it would freewheel and the pedals could be relaxed in whichever position desired. The final drive ratio with the belt+sprockets was 9:1, but with the torque converter in its most aggressive gearing was 6:1. With the torque converter, the top speed was 56 miles per hour, with a lighter-than-me jockey.
Gas Tank and Plumbing
Next I describe what was the most difficult part of this project, the gas tank : making a big metal container with a lid on the top, and a hole at the bottom! The biggest concern was fitment. It would have been embarrassing if I had spent significant time making a glorified thermos, without a good fit. To make sure I would not suffer such a fate, some accurate and slightly undersized templates were made to fit inside the top section of the frame.
Fabrication sequence: The two cut-out side panels are welded to a single sheet of steel, with the thinner back sections sloping inward to give the tank a more tear-drop shape. The excess material is cut off after all panels are fully welded, and in the event there are holes after the cutting and grinding, they will be filled with lead (brazing the holes in with solder). If this method of plugging holes doesn’t work, then gas tank liner will be poured in and used to once and for all prevent leaks.
With the tank ground down and looking far more like a gas tank, it is ready to be drilled and cut to receive a cap as well as mounts. All pieces mounted to the gas tank are connected via brazing. The gas filler neck/bung is unusually wide, so it is cleverly attached in a sleek offset method. The surface area of the pieces should allow the connection to be strong enough, though for a redo of any part of this, I make all pieces from steel, and use traditional brass brazing rods to make all connections.
All the bass inserts are shown below on the bottom of the tank. The two not yet brazed, to the left of the tanks center line, are to mount the tank to the frame. The bottom right nipple is to mount the gravity-bowl-type filter, and the top right bung is for the sight-glass fuel gauge.
This is a more detailed look at the fuel gauge and its mounting. It is a very basic method of checking your fuel, but is effective.
Finishing Touches and Changes
So what’s the final result? Well, the final result was a bike I used everyday for its practicality, and low maintenance, aside from the occasional oil and brake pad change. This was my go-to vehicle so long as it had gasoline in the tank, and in the mild California winter, the time of year did not matter. One may notice that the bike I sit on in this photo differs slightly from the previous pictures. A crack developed in the lower frame, and was reinforced at the point that was essentially the fulcrum. A larger pulley can be found on the engines crankshaft, and the starting system is the pull start the engine originally came with. I switched to higher quality and fatter tires for better top speed handling and to provide more cushion for bumps and potholes. The choice to use standard bicycle parts for consumables proved convenient, if I needed a brake cable or brake pads, I could go to any bike shop.
What Did I Gain?
This was a project that actually frightened me. I have yet to accept defeat by not finishing a project, and there were several small things that didn’t make it into the above reading material. They were small issues that had to be fixed. The Board Tracker project spanned from the middle of my sophomore year in High School to the beginning of Junior year. Even at the end of the fabrication and painting, there were several issues with the engine and fuel delivery. In the picture above, I was on my third engine block. All the engines were tired, used lawnmower engines with varying differences between bore and stroke length, all of which were yielded a weak engine that I eventually overworked. I finally got my hands on the highest-power version with that engine block. I even milled a few thousandths off the cylinder head to increase the compression ratio. In the end, I believe I had a whole 3 or 4 horsepower. I learned all about air fuel mixtures, and on damp and humid days, the effect certain conditions have on how clean burning an engine can be. Overall, this is the projects that made me become more confident with internal combustion engines, their tendencies, as well as how they work (something that became very clear after rebuilding my second engine for the third time). This is the project that gave me the confidence to take on the Jeep restoration, a later project.