By the early 1980s, the company needed to lift its street bikes from the doldrums so enter the VF750F Honda Interceptor.
It’s been speculated that Honda’s V-4s were rushed to market after the launch of the Suzuki Katana, and with the expectation of a new contender from Yamaha that became the FJ1100. Honda appeared to have taken its eye off the ball: its mainstream bikes were sturdy and reliable, but stodgy and dated. Yamaha, Suzuki and Kawasaki had all developed DOHC inline four-stroke fours, while Honda relied too long on its SOHC design from 1969. And while technically sophisticated, neither the Gold Wing nor the CBX were considered mainstream: Honda’s volume marketplace lead was slipping.
Then the V-4s arrived in 1982. First came the V45 Sabre for the US market, and the VF750S for Europe. All had liquid-cooled over-square engines of 70 by 43mm, six-speed transmissions and shaft drive. The short stroke, four-valve heads and narrow included valve angles were all state-of-the-art for high-revving, high-power performance. Then in 1983, the VF750F Honda Interceptor joined the US range.
Though based on the V45 Sabre, the VF750F Interceptor was also derived from Honda’s FWS 1000 US Formula 1 Championship Superbike racer. For the 1983 AMA Superbike season, four-cylinder bikes were limited to 750cc and were required to be production based. Honda management decided to build a new streetbike around the Sabre engine but with the right stuff to be a Superbike contender. The 1983 VF750F was the result.
The VF750F used a perimeter frame of square-section steel tubes enveloping a strengthened 750cc V-4, which was tilted back to allow for a shorter wheelbase and better weight distribution. Its engine shared most components with the Sabre, though changes to cam timing and combustion chambers resulted in extra horsepower. A more race-suitable chain final drive replaced the Sabre’s shaft, while the number of cogs in the transmission went, curiously, from six to five (apparently, reconfiguring the tranny for chain drive meant less room for gears). The transmission also included a new slipper clutch, with half the clutch plates driving the clutch hub through sprags, so the clutch was only 50 per cent effective on the overrun. Using similar engine internals to the Sabre meant the Honda Interceptor retained the former bike’s chain drive to the four overhead cams.
Completing the racer-on-the-road formula was a 16-inch front wheel attached to a fully adjustable air-assist Showa fork fitted with Honda’s TRAC anti-dive system. Rear suspension was Honda’s own Pro-Link with fully adjustable air-assist Showa shock. Comcast alloy wheels carried floating discs, two at the front and one at the rear, each gripped by twin-pot calipers.
But there was trouble in paradise: within months of the VF750F’s introduction, customers were returning to their Honda dealers with mechanical noise from the cylinder heads. On opening the engines, technicians noted excessive camshaft wear and disintegrating cam chain tensioners.
Honda’s response was a series of service advisories that attempted Band-Aid solutions under warranty rather than a full recall, and a number of minor engine changes ensued, mostly aimed at improving oil flow to the cam boxes. There were also service bulletins entreating technicians to be especially vigilant about setting valve clearances. This may have helped some with the cam wear problem, but didn’t resolve cam chain/tensioner issues. The fragile tensioners could disintegrate in just a few thousand miles, causing further engine damage.
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Clean, simple and stylish line. The bike looked like nothing else on the road, as it still does today. But, as is the plight of many sport bikes, remaining in a preserved and unscathed state after new and more exciting bikes enter the market is rare – especially one with a troubled origin story. Which is why pristine bikes like the one above can arrive to a small but enthusiastic audience at auction as it does hold a unique spot in sport bike history. This particular bike appeared at a 2020 Mecum auction in Las Vegas. (Photo: Mecum Auctions)
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The original Honda Interceptor weakness turned out to be an engineering fault, something almost unheard of from Honda. But why were only the cam-chain models affected? Obviously gear-drive engines weren’t susceptible to cam chain/tensioner problems, but the valve operation from the camshaft was identical. There’s an important clue in the press information for the 1985 introduction of the larger VF1000R: the engine, noted one magazine, has “new cylinder head castings to provide more camshaft support.”
Eventually the underlying cause was revealed: for the chain cam models, the camshaft towers were simply milled out to accept the camshaft and fitted with off-the-shelf caps. This could allow the camshafts to move, compromising the mechanical integrity of the valve train. In the gear drive models the towers and caps were line bored. A special factory tool to correctly locate the camshaft during valve adjustment made a big difference, but by this time the V-4’s credibility was shot. Honda had a new range of inline fours waiting in the wings, and the V-4s were dropped—except for the gear-drive VFR750F, which replaced the VF750 in 1986.
The new Honda Interceptor engine used a 180-degree crank instead of the VF’s 360 degrees and featured six gears. New valve timing, revised carburetion and a bigger airbox increased power to around 105 hp at 10,500 rpm.
The cams were driven by a “cassette” gear train running on ball bearings operating individual rather than paired rockers with increased lubrication. The new motor went into a perimeter beam alloy frame with revised steering geometry but with similar running gear to the VF750. The result was a weight reduction of 50 pounds, an 11.32-second quarter mile at 122.11 mph and a top speed of 149 mph.
A lot was riding on the VFR750F and Honda was determined to get it right. And they did. The 750 and later 800 Interceptors are widely regarded as some of Honda’s best, and remained in production for many years—though the cams were chain driven.
The Interceptor also begat the double World Superbike championship winning RC30.
By Robert Smith Canadian Biker Issue #309
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VF1000R – Honda’s Rushed to Market V4 Revolution
Royal Enfield MkII Interceptor
Honda Stateline, Interstate and Sabre (Review) – Touring With Hints Of Hotrod
Honda Interceptor 800 – A More Mature Approach (Review)
Built From Scratch – AJS V4
Moto Parilla – A Racing Influence (Vintage)
The Group of Seven : Picking the Great Motorcycle Engines
Timing is Everything! : Engine Timing