Honda SL350 History : When Yamaha stirred it all up back in 1968 with the DT1 250 trail bike the future of motorcycling took a very specific and divergent turn. The days of making a half-hearted attempt at an off-roader were over.
Honda’s immediate response was actually little more than a papering over-the-cracks exercise; it might even be seen as a cynical effort. The first Honda SL350 really was little more than a CB350 in a pretty summer outfit. The bike’s mass at 364lb (165kg) meant it was still far too heavy for its intended purpose: Honda arguably still hadn’t quite grasped what a trail bike actually was and was still too focused on the desert sled side of things as successfully capitalised on by the big Brit twins.
The CB’s geometry meant that the ‘new’ SL had too much understeer on fast bends and the power came in a little too hard at 5.000 RPM. The bike was okay but not exactly what the market wanted; there was too much CB about the bike; it even retained the roadster’s electric start. However, there were two facets of the Honda SL350 Motorsport that everyone seemed to love; the looks were stunning and the saddle was one of the most comfortable ever.
With customer feedback taken on board, Honda’s 1970 offering was an altogether better machine. If the Honda SL350 K1 wasn’t a totally all-new machine it was pretty damn close. The heavy single down tube frame had been dropped in favour of a purpose-built lightweight twin down tube chassis; this helped drop weight by an astonishing 60lb (27kg). Smaller slide carbs had replace the previous 30mm CV units, which had had a nasty habit of slamming shut when landing from higher jumps – never the ideal scenario on the dirt! The electric foot was also dropped.
A heavily revised camshaft allowed for maximum torque to be delivered at a much more reasonable 6.000 RPM and although the peak power had dropped from a claimed 33 to 25 HP the motor was much more usable. Revised frame geometry, increased trail, redesigned forks and different shocks all contributed to make the Honda SL350 K1 the bike the K0 should have been. Smaller diameter brakes more in-keeping with the bike’s intended use pretty much completed the upgrade and Honda was onto a winner. There were a host of minor revisions in 1972, including the fitment of a 21in front wheel in place of the previous 19in unit, revised paintwork and the adoption of anodised alloy guards in place of the previous painted ones.
This, the K2, was the end of the line for the Honda SL350. The Japanese had taken a longer term view and realised that it was simply not viable to run an essentially compromised design based on a road bike in a rapidly expanding market sector. Late 1972 saw the launch of the purpose-made XL250 Motorsport. This single re-established the genre that had pretty much died out during the death throes of the British bike industry and arguably it would lead to such ground-changing dirt bikes as the seminal Yamaha XT500.
Honda SL 350 Specifications
Engine : Air Cooled, Four Stroke, Twin-Cylinder, SOHC 4-Valve
Displacement : 326 cc
Bore x Stroke: 64 x 50.6 mm
Compression Ratio : 9.5;1
Carburetion : 2x 36mm Keihin CV
Max Power : 33 HP @ 9.500 RPM
Transmission / Drive : 5-Speed / Chain-Driven
Weight : 165 Kg
Front Suspension : Telescopic Fork
Rear Suspension : Dual-Shock
Front Brakes : Drum
Rear Brakes : Drum
Front Tyre : 3.00 - 19
Rear Tyre : 3.50 -18