Back in the early 70s, I was competing in AMCA MX (Scrambles as they were better known in the UK at that time). My old Greeves Hawkstone, named after the famous Scramble’s course near to Market Drayton, in Shropshire, was just about competitive in the 250-cc class against such bikes as early CZs, Cottons, and Bultacos. But it was obvious, the world of MX was about to be turned on its collective head when one day in 1974 a competitor turned up with a brand-new Kawasaki KX250.

 

Back to their BSAs

We had all heard about (but few had seen) the Honda CR250s and 125s cleaning up in the States with rider Marty Smith at the controls, but less was known about this green bike. The new Kawasaki had a crowd around it before it even came off the trailer. Part of the old crowd dismissed it as yet another badly made Japanese bike and made their way back to their old BSAs, others – me included – knew this was the future and no wishful thinking or rose-colored glasses were going to change what was inevitable: Scrambling was going to change dramatically. 

By the end of first practice most of us had seen the Kawasaki come by at a rate of speed we could only dream about, discussions about the likely results focused on who would get 2nd place! A quote in a Cycle News test probably put it best:  “ lt does nothing radically; but does everything well.”

The design and specification of the KX were not radical either. A somewhat standard looking frame was claimed to be made from chrome molly (SAE4130) tubing, but most people tended to have suspicions about the Japanese chrome moly (it was not to the same specification as American or European metals!).

Nonetheless, the frame was sturdy and the head-stock well braced. The single down-tube splays into two tubes just below the forward motor mount. These two tubes give some protection to the engine’s outer cases. However, something that didn’t get protection was the expansion chamber which ran below the frame (I held out hope that this would prove to be the Achilles heel of the Kawasaki, allowing my old Greeves to come good with its high mounted pipe. I was clutching at straws!). 

Criticism

The front forks came in for criticism when the bikes were new as they were generally stiff until the bike had been ridden for a few hours. The rear shocks on the other hand worked well straight from the crate but lasted just a few races—a typical problem with early Japanese shocks. 
 With a dry weight of just 214 lb.’s, the Kawasaki engine didn’t need bags of power to be competitive, but with around 30hp on tap, it was quick. And although these bikes would tend to buck and skip on some of the hard European tracks with multiple bumps, power delivery guaranteed they would out drag most of their competitors (including my Greeves by a long way!)

The engine was a conventional air-cooled piston-ported unit. The 246-cc engine (69.5mm bore x 64.9mm stroke) was fed by a 34mm Mikuni carb and had a CDI ignition system.

Interestingly, while most of the Kawasaki’s specification was within the expected norm, the rear wheel was a 19” unit which for a time made getting replacements of other makes a problem (most MX bikes use a 18” unit).

1974 Kawasaki KX250 Specs:

Engine: 246-cc air-cooled, piston ported, 2-stroke
Gearbox:  Close ratio five-speed
Carburation: Mikuni VM34SC
Ignition: Denso CDI
Front wheel: 300 x 21”, rear 4-50 x 19”
Price new: $1150
A 1974 version in perfect condition is valued around $5800.

Further reading:

Riding Vintage and Classic MX, the Basics