Down and Dirty in Arizona

A vintage AHRMA racing weekend with two of the cruelest and most medieval bikes ever devised: the OSSA Stiletto and Yamaha MX125.

| July/August 2019

 OSSA-track

In the smash documentary, Free Solo, about climber Alex Honnold, researchers performed an MRI on Honnold’s brain to see how his hippocampus alighted when Alex viewed stressful imagery. The minimal activation revealed why he might free climb Yosemite’s 3,600-foot vertical El Capitan alone, and without ropes: Some people just need more stimulus to feel fully alive. Coupled with nostalgia for the golden era of motorsports, this surely drives many vintage racers — car and motorcycle alike. Myself included.

There’s no comparing a 1970s Porsche 911 and a modern Carrera, or a solid-axle Corvette and a C7. They carry the same nameplates, but are worlds apart in character and capability. The same is true with vintage motocross bikes and their modern fuel-injected counterparts; the former often derived from period street bikes, while the latter are bespoke, CAD-CAM honed, competition dirt machines. Around my garage lurk both, including various vintage race bikes built up over recent years for events. And with several of them nearly race-ready, I decided to take a shot at the season-opening American Historic Racing Motorcycle Association (AHRMA) Vintage Motocross national in Buckeye, Arizona.

Vintage race cars have numerous fluid systems that require careful maintenance, namely hydraulic brakes and clutches, fuel pumps and cooling systems. Vintage bikes (generally regarded as 1974 and earlier) blissfully escape this, allowing even a long-moldering bike to be put right with a change of gearbox and fork oil, fresh fuel and tires, carb and air-cleaner service, some spot lubrication (e.g., cables and brake cams), and fresh rubber. It’s a genial day’s work if nothing goes wrong and no oddball parts are required.



loading-bikes
On track aboard the OSSA (left), Unloading bikes in the pits at Arizona Cycle Park.

The bikes

Three bikes were prime candidates, including a 1971 OSSA Stiletto TT, a 250cc 2-stroke Spanish racer built in Barcelona by the projector company, Orpheo Sincronic Sociedad Anónima (OSSA). Featuring shapely but frail fiberglass bodywork and a powerful — but likewise frail — engine, it is fun to ride and had previously been rebuilt in 2011. Dunlop’s latest MX33 soft- and intermediate-terrain knobby tires fit perfectly (dirt bike tire sizes haven’t changed much over the decades), and after modest attention paid to other mechanicals the bike was ready. Incidentally, compared to modern bikes, machines like the OSSA provide an interesting glimpse of postwar national processes. Doubtless much machining, fabrication, assembly and details were done by hand, including the pinstriping on the lovely fiberglass bodywork. Sure, the OSSA has foibles; but it also has soul.

Next up was a 1974 Yamaha MX125; it’s the proletariat dirt bike novices would buy, while the related YZ125 was the serious weapon. Although sporting different color schemes and bodywork, the two chassis were nonetheless nearly identical; the differences that count hide mostly inside the 125cc reed-valve induction 2-stroke engine. This particular bike had a YZ125 engine race-built for the 2011 season, and like the OSSA, was essentially ready to go. Its stout 1974 YZ250 fork — an allowable upgrade per AHRMA rules — had been worked over, as had the OSSA’s, by Race Tech and was good to go. All it needed was air-filter servicing, some cable guides installed (the last time I raced it, a snagged cable locked the front brake, gifting me with a trip to the ambulance), and another set of grippy Dunlop MX33s. Light duty, all told. Just three years newer than the ’71 OSSA, the Yamaha is a product of a different mindset — Japan was less than 30 years past wartime annihilation and had already become a world-class manufacturing entity. The difference in design, engineering approach and quality is marked compared to the Old-World OSSA.

The contemplated third bike for the adventure, a striking red 125cc Rickman-Zündapp, was an English-built motocrosser with a German 2-stroke engine. Although it had raced most recently in the Alabama woods at Barber Motorsports Park, it’s not as vociferous a racebike as the screaming Yamaha, and so it was left asleep, a redundant relic forced to await action on another day.

The prep

I truly hate the last-minute thrash that inevitably seems to come with racing weekends, and so ahead of the AHRMA season opener, I worked hard to get my work done, the bikes prepared, and training sessions (mainly pool, running and cycling) logged as best as possible. As any racer knows, race prep is always 10 pounds of stress in a 5-pound bag.

And that is why, the 2019 Chevy Silverado 4WD Crew Cab LTZ didn’t get packed — in driving rain and wind mind you — until nearly midnight on Friday. Naturally, the garage was left behind in shambles, tool boxes were chucked inside the cab, and the bikes’ seats and gas tanks were hastily protected with taped-on garbage bags. Steel rings in the Silverado’s thankfully excellent anti-slip textured bed allowed easy tying down of the bikes, although the short 5-foot-10-inch bed required the tailgate to be lowered. And another thing: Despite the included bumper corner steps, the tailgate’s high step-up height proved annoying; GMC’s new transformable MultiPro tailgate would have been a plus. Plus, everything inside the bed needed to be tied down for safe transit. That included an ice chest, bike stand, twin 5-gallon gas cans (carrying $168 in race gas), and a box full of oil, chain lube and cleaners. Motorcycle rule for automakers please: All pickups shall have 7-foot beds!

Racing the lashing rain-front, I met photographer Seth DeDoes in Orange County, California, and we trucked eastward through Indio and past Palm Springs, across the desert, and toward the Arizona state line, finally getting ahead of the storm.

The park

Lime Rock Park the Arizona Cycle Park is not. Situated on reclaimed land within sight of a state prison, the MX facility is nevertheless rather artfully done. Utilizing what looks like an old quarry, several tracks wind around a massive sunken area, giving a great view for those watching up on the rim. While the more recently added vintage track — an easier circuit that lacks the breathtaking jumps characterizing modern tracks — occupied a relatively flat area on the perimeter of the facility.

OSSA-camp
Making camp.

DeDoes and I missed registration by a half-hour, and so busied ourselves unloading the two bikes, re-taping the now shredded plastic in anticipation of forecasted evening showers, and preparing respective sleeping “quarters”: Seth in a streamlined mountaineering tent in the dirt and me inside the Silverado’s rear cab. As night fell and the rains advanced into Buckeye, it was hard to tell who’d made the smarter (or dumber) choice. The ripping wind, sporadic showers and the drone of a generator nearby gave Seth a fitful night’s sleep. And as I painfully discovered, the Silverado rear floor is no place for camping. A central hump in the floor creates a pressure point mid-spine that simply cannot be escaped without creating a bespoke subfloor, which I couldn’t manage with a sleeping bag, jacket or towels. Somewhere between midnight and dawn I gave up on the floor, flipped down the rear seats and somehow got a few winks there. On the positive side though, parked nose into the wind, the Silverado stayed nearly silent inside; the aero and insulation is so good that there was nearly zero evidence of the generator or wind howling outside. Impressive.



pre-race-meeting
The pre-race rider’s meeting.

Race day

Dawn couldn’t come soon enough, and at 7 a.m., race organizers turned up some sunny ’60s rock, kindly lady volunteers manned, so to speak, the registration tables, and raceday began. Step one was paying an $85 entry fee for two classes — an age-group class for the 250cc OSSA and a “Sportsman 125” class for the 125cc Yamaha. Step two was taking a copy of the sign-up form, along with both motorcycles, to tech. Typically here, the tech inspector checks the front suspension and steering for play, ensures that the throttle is self-closing, that the brakes work correctly, and that the rear shocks conform to the 4-inch travel limit. They don’t pay much — if any — attention to front suspension travel.


A little stretching before the race.

Practice is minimal — just a few five-lap sessions assigned to different bike classes and rider groupings. Far from lengthy, it’s just enough to learn the track layout, in this case a serpentine dirt course that rises and falls modestly, and darts and feigns around desert shrubs. “If you go off course, don’t hit a bush,” warned an official. “They’ll be pulling needles out of you forever!”

As in other forms of racing, starts are crucial in motocross. In most AHRMA vintage races, 10 to 20 riders line up behind a steel gate. When the starter moves a lever inside a plywood “doghouse,” all the gates drop in unison and the race is on, with riders rushing to the bottleneck of the first turn. Get a good launch out of the gate and you have a shot at escaping the pack with the leaders, but muff the start by wheelieing, spinning the rear wheel or bogging the engine and you’ll spend the first lap eating dirt-clods and dust. Either way, motocross is about as exciting as big-wave surfing or skiing off-piste; it’s barely contained chaos.

starting-gate
The starting gate.

The bedlam of the start doesn’t exactly end after lap one, as the mechanical character of the bikes keeps giving and giving … punishment. In other words, unlike the smooth powertrain and silent interior of the Silverado, nearly half-century-old 2-stroke motocross bikes are diametrically opposite — demons, really. Their unitized engines and transmissions are tidy enough in design, with the crankshafts turning on ball bearings, the big ends on roller bearings, the top ends on needle bearings, and the gearboxes on ball bearings and/or bushings. Ingeniously, the combustion chamber is fed its air/fuel mixture not by valves but by a set of fixed intake, transfer and exhaust ports cast into the cylinder walls; the mixture is shuttled from combustion chamber to the crankcase via transfer ports and the positive and negative pressure spikes created by the piston moving up and down, and the exhaust pipe design. As they say in dating apps: “It’s complicated.” VP C12 race gas mixed with Maxima Castor 927 at 32:1 lubricates the piston and main and conrod bearings via mist.

OSSA-race
Chasing down the leader aboard the Yamaha MX125.

The miracle of 2-strokes is their power stroke every 360 degrees vs. 720 degrees in a 4-stroke engine. Developing frenetic power over a narrow rpm band is the signature of the vintage 2-stroke MX engine, and along with it comes frightful vibration and noise emanating through and from the thin-wall steel expansion chamber exhaust, shaped to augment cylinder charging within a specific rpm range. Typically about 32 inches wide, the handlebar ends alight with buzzing, and the entire chassis, seat and footpegs do the same. Add together the noise, vibration and commotion of racing a two-wheeler in a pack on slippery terrain, and you have yourself ample brain activation.

riding-motocross
On track aboard the Yamaha MX125, grinding it out to the end.

Good athletes make any sport look easy, and the same applies in motocross; although it may appear as though riders are just “sitting” on their bikes, this is hardly the case. Racing motocross vigorously is akin to working every machine in the gym simultaneously at maximum effort atop the greased roof of a moving bus, while dressed in 15 or 20 pounds of boots, body armor, helmet and apparel. It’s a hot and heavy, down and dirty business, in which lean muscle mass and cardio fitness is your friend.

race-finish
Two motos were all the OSSA had left, but the day was still a win.

One might wonder what sort of people race vintage motocross. By observation, it’s majorly Boomers imprinted during the 1970s by the excitement, machinery and popularity of the sport. Now decades later, they still find it enrapturing, recognizing that the era and activity represents a high point in their lives. Who can argue with that?

The start

Our Buckeye race day mercifully proved not rainy, but pleasantly cool and sunny. This helped due to the heavy burden of protective gear — which just might be the most of any activity save military combat, spacewalking or hard hat diving — plus the heavy exercise that motocross requires. (For instance, in monitoring my heart rate during 5k and 10k races and riding motocross, running topped MX in maximum sustained heart rate by just 9 beats per minute or 6 percent — meaning that motocross is truly heavy-duty exertion.)

Waiting on the gate before a motocross race start is a bit more nerve-wracking than starting a car race. The reason is related to fight or flight: In a rolling-start car race, I’d review my game plan for the first turn during the pace lap, but be simultaneously comforted by the steel, belts and window net cocooning me inside the car. On a motocross bike there’s no sighting lap and it’s just you, the dirt, and a bunch of spinning chains, sprockets and knobbies, bikes and bodies.

Motocross uses a two-moto (i.e., two-race) format. In professional AMA Motocross, each moto is 30 minutes plus two laps. In AHRMA, due to the frailty of the older bikes (and some riders!) and manifold classes, motos are typically five laps. My Buckeye weekend included two practice sessions and four motos, totaling about an hour of hard work.

motocross-bikes-truck
A full bed: Two motocross bikes, fuel containers, and stand, a cooler and a ramp make for a tight fit.

Cars got “juice breaks” in the 1920s, but over 50 years later, motocross bikes were still totally mechanical devices, with no hydraulic assists whatsoever: The throttle, drum brakes and clutch are operated by cables (and many rear brakes by a steel rod). Perhaps obviously, there are likewise no electric starters, traction control, stability control or ABS. Launching out of the gate is akin to a drag-race start, requiring precise unified engagement of the multiplate wet clutch while managing engine rpm. Here and literally everywhere around the track, grip is essential. Racing is all about grip anyway, and doing it in the dirt is no exception.

The revised tire carcass, sidewall, knob design and rubber compound of the new Dunlops meant both race bikes were on as good a footing as possible — actually, on par with what pros run in certain conditions. And you can visually see the difference between one bike with older, worn knobbies fishtailing for grip down the straightaways and the experience of riding on the new MX33s. If I were to go down in Buckeye, it wasn’t going to be due to old rubber. Which reminds me of a great thing about dirt riding and in particular motocross: It’s a constant exercise in looking and feeling for traction, terrific mind and skill sets that translate to the street, on two and four wheels alike.

The Yamaha MX125 is hard as hell to launch. It’s tall and has a short wheelbase, and the aftermarket PVL electronic ignition on its built YZ125 engine has almost no flywheel. In the first of its two motos, the motor bogged and I got a poor run to the first turn, narrowly missing a pileup of bikes and riders before making some passes to finish second in Sportsman 125. Brutally slipping the clutch in the second moto netted a cleaner start and the Yamaha pulled through for a class win.

The OSSA’s two motos held more drama. It’s easier to launch and I got to the first turn inside the top five both times. In the first turn of moto one, a big hit to the left rear number plate advised me that someone got in too hot behind me, leaving bear-claw shaped rubber swipe marks on the white plate. That moto likewise netted a second in class. The day’s final moto — among an amazing 34 races held in Buckeye that day — proved the engine’s swan song. After a good start and a diligent race, on the last lap the motor soured halfway through the lap, making ominous grinding sounds I could hear even above the din of other bikes and through the high density foam earplugs I always wear. The engine dragged more and more in the final sectors, and then expired in the last turn. Hopping off, I pulled in the clutch and pushed the bike across the line, far enough ahead of the next rider to score a class win. (A later teardown revealed a snapped crankpin — the fault of no one except, perhaps, time, stress and some Spanish steel company in 1971.) The bike had given its all.

Regardless, two seconds and two wins resulted in two class overalls: Not a bad weekend. As well, 25 or so motocross laps at speed are plenty to tax the body. The post-races physical assessment: Worked shoulders and forearms, “monkey butt” (don’t ask) and ringing ears, despite the earplugs. In my experience, karting or car racing can work the upper arms more but the lower arms, hands and legs way less.

I like to call vintage 2-stroke MX bikes the cruelest and most medieval devices money can buy. They’re loud, vibrate like a paint shaker on overdrive, the 7-inch front, 4-inch rear suspension (vs. a foot at both ends on modern bikes) is at best just adequate, and the brakes lack both power and feel. Comparatively, climbing into the Silverado LTZ at day’s end for the long drive back to SoCal was like an unexpected serving of smooth, tasty crème brûlée after a meal of rocks, dirt clods and sand. Although on our test unit I found the ride quality and seating less than comfortable, by comparison it was pure bliss.

And a worthy reward after a hard-fought day in the dirt. MC

rick8928
6/13/2019 7:04:06 AM

Very well written and captured the gestalt of vintage bikes. Perfect phrase that describes my own situation to a tee: "By observation, it's majorly Boomers imprinted during the 1970s by the excitement, machinery and popularity of the sport."




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