Around-Town Ripper: 1967 Bridgestone Hurricane Scrambler
1967 Bridgestone Hurricane Scrambler
- Engine: 177cc rotary-disc valve, air-cooled 2-stroke parallel twin, 50mm x 45mm bore and stroke, 9.5:1 compression ratio, 20hp @ 8,000rpm
- Top speed: 85mph
- Carburetion: Two Mikuni VM17SC
- Transmission: 4-speed rotary with 5-speed sport selector
- Electrics/ignition: 12v, electronic ignition (coil and breaker points ignition stock)
- Frame/wheelbase: Single downtube steel cradle frame/48.6in (1,234mm)
- Suspension: Telescopic fork front, dual YSS shocks w/adjustable preload rear
- Brakes: 6.2in (157.5mm) TLS drum front, 6.2in (157.5mm) SLS drum rear
- Tires: 3 x 18in front and rear
- Weight (dry/stock): 271lb (124 kg)
- Seat height: 30in (762mm)
- Fuel capacity: 2.64gal (10ltr)
- Price then/now: $650/$1,300-$3,300
Thanks to a gas-guzzling pickup truck, Josh Withers discovered motorcycles. “I didn’t need to drive the truck all the time,” he says, “so I wanted to get a motorcycle, something a bit more economical to get around on.”
In 1998, Josh picked up a ratty Yamaha Virago, which he rode for five or six months before he traded it and $50 cash for a mint Kawasaki 440 LTD. A variety of machines followed, but for Josh, one thing always remained the same — he liked to add a few custom touches. A different set of signal lights, a different handlebar or a different seat, just something to set his bike apart from all the others. It was that attitude that eventually led him to vintage BMWs.
“I was going to buy a Ducati Monster, but at that time you’d see one of those on every corner in San Francisco, California, where I was living,” Josh tells us. “So I was talking with a mechanic who said to me, ‘Why don’t you buy an old bike and make it new?'”
That mechanic was the now-retired and well-respected Dave Gardner of Recommended Service. Under Dave’s mentorship, Josh bought a basket case 1977 BMW R100S and put it back together. Since then, Josh has made something of a name for himself customizing several German motorcycles. Check out the July/August 2009 issue of Motorcycle Classics for a story on his 1973 BMW R60/5 Special.
However, this story isn’t about one of Josh’s favored Teutonic chrome-plated Toaster-tank creations. Instead, this is a story about a wayward Bridgestone that should have been a Lambretta.
“I was going to buy a 1972 Lambretta scooter from a friend for $3,000,” Josh says,”but we couldn’t get it running, and for that money it sounded like an expensive non-running project. That’s when the Bridgestone caught my eye.”
On Facebook, Josh saw a post from someone trailering a 1967 Bridgestone Hurricane Scrambler from Idaho to a buyer in the Los Angeles area, where Josh now lives. As these things go, however, there was an issue. At the eleventh hour, the buyer had backed out of the deal and the driver needed to unload the Bridgestone. That’s when Josh entered the picture. He thought $700 for a cool old machine he’d never heard of before and with a chrome-plated tank similar to his beloved BMWs sounded pretty cheap.
“It was supposed to run, but when he pulled up I could see immediately the Bridgestone wasn’t ‘as advertised,'” Josh says. “So I got the price down to $500 and bought the bike. I didn’t plan on restoring it, I like to buy my projects cheap and beat up and then make them my own, but I didn’t realize how bad it really was.”
With the well-used Bridgestone on the bench at a local shop, Josh had help to initially fire up the Hurricane Scrambler. It took some effort, but as soon as it was running Josh realized there were issues with the coils and charging system, and the bike also produced plenty of exhaust smoke.
That’s when he made the decision to pull the Bridgestone completely apart and have some fun creating something he describes as an “around-town ripper.”
To start, Josh completely dismantled the Bridgestone. He pulled the top end of the 175cc parallel twin engine and sent the head and cylinders out for polishing before lining up an engine builder who promised to completely rebuild the power plant to like-new condition.
Where it all started
Before we get too deep into the engine rebuild of Josh’s Hurricane Scrambler, let’s a take a quick look at Bridgestone’s background. If the name Bridgestone brings to mind tires more than motorcycles, that’s because the company was formed in 1931 in Japan as a tire company.
After World War II, Bridgestone expanded into wheeled goods — while still making tires — and in 1946 started manufacturing a line of bicycles. By 1950, Bridgestone was constructing a 26cc clip-on engine meant to easily attach to a bicycle, and it wasn’t long before full-scale mopeds and motorcycles were in the works. One of the first was the 1958 Champion moped. With a pressed-steel frame, 24-inch wheels and 50cc 2-stroke engine equipped with pedals, it looked very similar to the German-built NSU Quickly.
Bridgestone engineers worked up a variety of models based on the Champion, but the big news came in 1963 with the development of the single- cylinder 2-stroke BS90 with rotary-disc inlet valve. In the early 1960s, Bridgestone broke into the lucrative U.S. market when the company began exporting the Bridgestone 7, a machine still based on the Champion 2-stroke, to the Rockford Scooter Co., Inc. of Rockford, Illinois. A growing network of U.S. dealers was served well by what became Rockford Motors in 1965, just in time to start selling the Bridgestone 175cc Dual Twin. Following soon was the 1967 introduction of the Bridgestone Hurricane Scrambler.
“In the ‘scrambler,’ as was and is true of the pure touring (Dual Twin) Bridgestone 175, the engine is the most interesting feature,” wrote the editors in the January 1967 issue of Cycle magazine. “This engine, which is packed with little items that should delight the technically inclined, was the first mass-produced 2-stroke ‘twin’ to have rotary-disc inlet valves.”
As Cycle told it, most 2-strokes up to this point had only a “hole” at the back of each cylinder for drawing in a fresh fuel charge, controlled by the rising and falling piston as it opened and closed the port. While it might be simple, the design could only be adjusted to work well over a limited range, Cycle explained.
“A disc-type rotary valve is much less handicapped,” Cycle continued. “By using this device, an engine designer can getany opening and closing points needed for the intake period.As a result, the power range will always be a bit wider, for anygiven level of output, when rotary valves are used. You may notcare about the technical ins and outs of the matter, but you willcare about the engine’s wide-range pulling power.”
Another technical enhancement of the Bridgestone twin was the use of caged needle roller bearings as opposed to bushings for the piston connecting rod wrist pins. Furthermore, the aluminum barrel featured hard-chrome plated bores, a feature that had been developed in high-performance racing 2-stroke engines. Also of note, Cycle said, was the two-way transmission that offered, with the flip of a lever, “a 4-speed ‘rotary-shift’ transmission, in which neutral was between 1st and 4th and you could get 1, 2, 3, 4, N, 1, 2, etc. endlessly by pressing down on the shift lever. Pull the ‘sportshift’ lever, which is mounted high on the side of the transmission, over the other way and you had a 5-speed gearbox, with a conventional ratchet change.”
This shift pattern was neutral, first, second, third, fourth, fifth, with the fifth gear acting like an overdrive when cruising at faster speeds. That’s how Josh likes to use his Hurricane Scrambler transmission, but to discover that, he had to get the motorcycle built. So while Josh’s Bridgestone engine was out for its rebuild, he focused his attention on the running gear.
From the bottom up
Starting with the wheels, new bearings went into cleaned hubs while the spokes and rims were cleaned and returned to service, as were the brake shoes. Josh searched for Bridgestone street tires to suit his Bridgestone project, but unable to source any in the 3 x 18-inch size required he settled on a pair of Zaps from IRC Tire.
At one time, a previous owner of Josh’s Bridgestone had equipped the bike with dual rear sprockets, one a larger 68-tooth and the other a smaller 58-tooth chain ring. These would have facilitated quick trailside gear changes by adding or taking away a short length of drive chain. Josh decided he liked the look of the dual sprockets and kept the 68, but switched out the 58 for a 46-tooth sprocket. While Josh won’t be using the 68-tooth sprocket, he clearly likes the look.
For the rear suspension, Josh got a set of custom YSS shocks made to suit the lightweight Bridgestone. Up front, the forks were cleaned and detailed, with cadmium plating applied to the springs and seal holders. A custom steering damper knob for a BMW from Oshmo Motorworks was threaded to accept the Bridgestone rod and Josh machined a new flat-sided and flanged nut to fit the bottom plate and friction disc. All parts that are Porsche Silver are powder coated, including the frame, stands, airbox and covers, lower fork sliders, handlebars and the headlight nacelle that houses a new-old-stock speedometer.
“That’s the crazy thing about redoing a Bridgestone,” Josh says of the project. “You can find an NOS speedo for $40, but other things, like anything rubber, are through the roof.” Josh kept the handlebars that came on the Bridgestone as he purchased it, but notes for the Hurricane Scrambler model they should be taller, and with a motocross-style cross brace.
Turning his attention to the gas tank, Josh found the original chrome was heavily pitted. That gave the chrome plater some headaches, but Josh is pleased with the final results. A sealant kit from POR-15 went inside the tank before he had it painted.
“A couple of painters didn’t want to paint over the chrome, but I found a guy in Long Beach — no name; he likes to fly under the radar — to do it, and he did a beautiful job,” Josh says, applying teal-colored paint to the top of the tank and around the edges, the chrome shining on the side panels.
Josh’s anonymous painter also applied the teal-colored finish to the front fender and the tail of the custom seat. Josh made the seat by cutting in half a steel dome meant to sit atop an industrial-style fence post and welding it to the seat pan. This gives the Bridgestone a tidy little tail section. The seat foam was carved and covered by Erwin’s Upholstery in Long Beach. Everything was reassembled with cleaned and freshly cadmium-plated Bridgestone hardware.
Details such as the white Gran Turismo-style grips contrast nicely with the polished throttle and switchgear housings, adding a measure of cleanliness to the Bridgestone, as do the Oberon bar-end mirrors. Motion Pro made custom cables with silver sheathing using original Bridgestone fittings, which Josh supplied, for all controls.
With the rolling chassis ready to go, the rebuilt engine was bolted into place and a Kawasaki KZ1000 electronic ignition was adapted to provide sparks. The engine ran, but Josh wasn’t too happy. The kickstarter wouldn’t return, it wasn’t charging, it was leaking and it was still smoking excessively. Even so, Josh got the Bridgestone out for a few short rides around town and was enamored with the new machine. After working out a couple of the issues, in December 2016 he set out for a longer “break-in” ride.
“I only got about 15 miles before I detonated both pistons,” he sighs. “But after that, and through word of mouth, I found a 2-stroke guru who goes only by the name of Victor. We found the timing had slipped, and that caused the detonation. Victor helped me put things right the second time around, and he even welded the heads and reshaped the combustion chambers to make an effective squish band with a more efficient burn.”
Josh also completely rebuilt the dynamo charging system and added a modern rectifier formerly sold by Radio Shack.
This time, he is more comfortable with the rebuild. Since finally getting the bike back on the road late in 2017, Josh isn’t fazed to ride the Bridgestone on his 7-mile commute to work or just to the corner store. It’s certainly no pickup truck, and as Josh says, “I’m just having some fun on it, ripping around town like I thought I would.” MC
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