Vintage Motocross Racing

By John L. Stein
Published on April 10, 2014
1 / 12
John Stein (983) fights for position with former AMA star Scott Burnworth (8).
John Stein (983) fights for position with former AMA star Scott Burnworth (8).
2 / 12
Airborne: A stock 1974 Yamaha MX125’s suspension is most suitable for play riding, but properly motivated it can still get up and fly.
Airborne: A stock 1974 Yamaha MX125’s suspension is most suitable for play riding, but properly motivated it can still get up and fly.
3 / 12
Stein makes camp at Marty Tripes’ inaugural Carlsbad Reunion at The Ranch, a 700-acre offroad motorsports park in Anza, Calif.
Stein makes camp at Marty Tripes’ inaugural Carlsbad Reunion at The Ranch, a 700-acre offroad motorsports park in Anza, Calif.
4 / 12
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
5 / 12
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
6 / 12
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
Shapely and powerful Ossa Stiletto TT is also buzzy; it shed both tank badges at Sonoma. Race Tech fork mods and Works Performance shocks were huge improvements.
7 / 12
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
8 / 12
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
9 / 12
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
Experience and expert advice helped Stein turn Yamaha’s proletariat 125 motocrosser into a formidable vintage weapon. Suspension and power improvements were critical.
10 / 12
The author and the Yamaha MX/YZ125 after a muddy Carlsbad Reunion moto.
The author and the Yamaha MX/YZ125 after a muddy Carlsbad Reunion moto.
11 / 12
The Stiletto TT was built for dirt-track racing, but a 21-inch front wheel and a longer Stiletto MX swingarm help prepare it for motocross.
The Stiletto TT was built for dirt-track racing, but a 21-inch front wheel and a longer Stiletto MX swingarm help prepare it for motocross.
12 / 12
The all-in cost for both bikes approaching the two-day Sonoma event soared to $9,916.
The all-in cost for both bikes approaching the two-day Sonoma event soared to $9,916.

Perhaps it’s some genetic deviancy, but the challenges of problem-solving and mechanical resurrection that old bikes offer are more than just fun — they’re irresistible.

So it’s little wonder I chose a pair of vintage 2-strokes, rather than nice new machinery, when I decided to pursue a national motocross title. The notion that it could be done cheaply was added incentive. But would it? Only trying would tell.

Affordable beginnings

You couldn’t start much lower than a 1974 Yamaha MX125, bought from a Craigslist ad for $700, for the American Historic Racing Motorcycle Association’s (AHRMA) Sportsman 125 class. However, one ride revealed the stock suspension was intended for flyweights doing laps in a dirt lot, as both ends bottomed at almost any provocation. Still thinking economy, I installed spacers to bump up the fork-spring preload and found a half-inch longer pair of shocks for $45 on eBay, and then tried it again at a local race. It was hardly any better. Luckily, a call to vintage motocross racer and Yamaha medicine man Dave Rymal located a perfect MX360 fork and triple clamps, a vast bolt-on improvement, for $200. I also installed a new piston and ring, points and condenser, Uni Filter, tires and chain for about $250.

Motor racing artist Hector Cademartori and I headed to Arizona Cycle Park for AHRMA’s first western national of the year — one of seven I had targeted. The little Yamaha was better, but it still bottomed on hard landings and the shocks and seat were punishing. The engine was also down on power in the 125 class and especially in the 50-plus age group class, which was populated by 250s and 400s. Still, the little bumblebee managed to win three of four motos and take both overall class wins for the day, trouncing much bigger CZs, Maicos and the like. Not bad for a total investment of less than $1,200. Maybe we had something here.

We left Arizona on a high note, inspired to develop the bike further. In the weeks before the AHRMA round at Sonoma Raceway, I yanked the front end and sent it to Race Tech for $515 worth of Gold Valve Cartridge Emulators, new springs, seals, fluid and labor. I also engaged Works Performance to build a $445 pair of steel-bodied Gasser shocks with dual-rate springs. The stock seat, with its tired 37-year-old foam, went to AMS Racing for a full rebuild, a purposeful inch taller to improve ergonomics, for another $175. SportCycle Pacific also welded on a $30 pair of footpeg extensions.

Comments (0) Join others in the discussion!
    Online Store Logo
    Need Help? Call 1-800-880-7567