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Ducati 500SL Pantah
Despite keeping its trademark L-twin layout with the front cylinder canted forward, the engine was a clean sheet design. Technically, it’s an all aluminum, 90-degree single overhead cam twin with two-valves per cylinder and Desmo valve actuation. Measuring 499cc from an oversquare 74 x 58mm bore and stroke the all new, vertically split cast crankcases did away with the kick start and housed a forged crankshaft running on plain bearings; both a departure from previous Ducati practice. More newness consisted of a spin-on oil filter, but tradition was kept with the cylinders retaining Ducati's novel engineering feature of vertical / horizontal finning. An upscale feature then, ultra-hard Nikasil was applied to the Pantah’s bores, filled with domed 9.1 pistons.
This mostly original, low mileage example sold earlier this year in Vegas for just under $9000, making the sporty 500 a somewhat affordable entry into the circle of vintage Ducati ownership. If other Ducati models from the era are any indication this likely will not be the case for long, especially considering the Pantah 500 SL's historical importance. I’m taken with the Ducati’s compact lightness, its angular lines and giant killer performance, making it a motorcycle I’d ride without fear. Later 600 and 650 versions offered improved reliability (gearbox, starter clutch) and upgrades like hydraulic clutch actuation. Buy to ride or sell for profit, the Pantah 500SL is a win-win. Nolan Woodbury
Being a fan of the angular style popularized by rival De Tomaso, I’ve long been drawn to the 500 SL and the Pantah models that followed. However, there remains some confusion regarding Taglioni’s motivation in designing it. Some believe company politics was involved, and Ducati wanted a mid-size machine more appealing than the unpopular parallel twin rolled out during the 1970s. Others think the company saw the Pantah as the new basis for production, but all agree Taglioni was the man to make it happen. Soon after Cagiva’s 1985 buyout, funding for a new engine meant the end was in sight for the towershaft twins. Based in large part on the Pantah, the new engine was liquid-cooled with 4v heads for fittment into the 851 Superbike...and the rest is history. The original 500 SL offered increased simplicity, lower production costs and ultimately more performance with less mass due to its compact construction.
Measuring two-inches shorter axle-to-axle than a contemporary Desmo 900, Taglioni’s work to downsize the Pantah begins in its trellis frame. Viewed from the side (Cycle photo>) sections of straight tube join to form a simple ladder; two horizontal bars from steering stem to sub frame and three vertical, the rear most looping under to attach a main stand. From this the engine connects with two tabs between the cylinders and four more tabs (two per side) behind the gearbox. A hole cast into the rear crankcase for the swingarm pivot shortens wheelbase and strengthens the assembly, which is made simpler with a conventional two-shock suspension.
“The Pantah’s dragstrip performance surprised us; it felt slow on the road,” wrote editor Phil Schilling, himself an esteemed member of Ducati lore. “The engine’s incredible smoothness, presumably flat torque curve and the still-air pocket behind the fairing send a false ‘seat of the pants’ sensation.” Ground clearance and handling received praise from above, the latter benefiting from ideally spaced transmission ratios and a distinct lack of driveline lash. “The Pantah’s suspension lacks the adjustability of top end Japanese models, but this is forgivable. A one-dimensional sports bike, the 500SL remains calm and controlled over normally troublesome cracks, bumps and dips…unruffled and unaffected at speed."
Formerly driven with bevel gears and tower shafts, that Desmodromic magic was now generated via a toothed belt. The bottom pulley is driven via a jackshaft taking its power from the crankshaft, connecting belts that run through a series of idlers and around each camshaft pulley. The assembly worked, remained reliable (good for 12K or more) in addition to being much easier to manufacture and service. Huge for a 500cc, fueling comes from twin Dell'Orto PHF 36mm carbs, the ignition is digitized, and the wet, multi-plate clutch transmits power to the Pantah’s five speed gearbox. With a factory rating of 50 HP @ 8500 rpm, the 500SL pulls through its tallish gearing to generate an honest 120-mph. (^ Ducati photo)
Ducati Pantah 500SL
Engine: Alloy inline 90° v-twin
Bore and Stroke: 74 x 58mm (498.9cc)
Compression: 9,5 :1
Desmodromic S.O.H.C. belt drivent
Intake: 2- Dell'Orto PHF 36mm
Factory rating: 50 HP @ 8500 rpm
Transmission: Five-speed gearbox
Primary drive: Gear
Final drive: Chain
Clutch: Oil-bath multidisc
Frame: Tubular steel trestle
Front suspension: 35mm Marzocchi teles
Rear suspension: 2-Marzocchi shocks
Front brake: 2-260mm w/1-p caliper
Rear brake: 1- 260 mm
Front tire: 100/90 18”
Rear tire: 110/90 18”
Weight (dry): 403-lb
Top speed: 120-mph
(Photos: Dave Chrone, Ducati, Cycle magazine and WMM)
Few expect flashy acceleration from a fully faired, 500cc Italian twin with tall gearing, but the Pantah posted very respectable numbers regardless. In a test published for the May, 1981 issue of Cycle, the 500SL posted a best ¼-mile time of 13.66 seconds by shifting the engine some 1800-rpm past its 8000-rpm redline. The test noted even quicker figures were earned by Euro editors who spun the engine into five-digit territory...and did so without breaking it. Note factory airvbox plumbing and 36mm Dell'orto carb. (Cycle photo>)
Both the fork and shocks were sourced from Marzocchi, the front with 35mm tubes. Uniform 260mm discs are fit, two cast iron Brembos in the front and a single rear, all pinched by small one-piston calipers. My research shows OSCAM wheels on early versions, followed by split-spoked FPS hoops. Fully gassed, the 500SL weighs a feathery 430-lb.
Of the European makers Ducati is among the youngest, due to its post WWII startup. That might explain the company’s reputation of promoting and implimenting the forward thinking technology founding engineer Fabio Taglioni is best remembered for. Living in a time when phrases like ‘iconic’ and ‘legendary’ are tossed out far too easily, the praise directed at Taglioni is justified. Not all of the mechanical platitudes behind the Ducati legend were invented by the engineer, but he made them possible.