Bertie Simmonds on the best V4 ever!
The SPR'S a tight fit, and even once I'd loosened up my joints it was still hard to move about, but once out on the road it felt more natural. The handling's secure and the road holding firm with grippy Bridgestone tyres on 17-inch three-spoke light alloy wheels. By modern standards the 150-wide rear seems skinny, but that only enhances the nippiness of the steering. At normal speeds the SPR feels dull: it's when the engine's singing above 6000rpm, which is easy to maintain with the closeness of the ratios, that it comes to life with a response to the quick-action twistgrip that's a joy. The surprise was that with just 45bhp on tap, the SPR felt so quick. Overall geometry of the SPR is the same as the Rand SP versions I'd also ridden, with a short 1340mm (52.8in) wheelbase, 24-degree steering head angle and just 90mm of trail. With a claimed dry weight of 132kg, slightly more than the SP'S 128kg, you'd expect nervousness in the handling that would demand your constant attention. But the SPR is nothing like that. At speed the bike feels planted and the steering is such that no more than a nudge on the footrests and a twitch on the bars guides the bike from apex to apex. While peak power is at 9500rpm, the red line is at 12,000rpm, making rewing to 11,000 easier than dropping a cog. Overall gearing is lower than you'd expect: I reckon the power is easily enough for a top speed of more than 120mph, but ratio in sixth is 7 to 1 on the 37/14 sprockets gives 113mph at 11,000rpm. But that doesn't really matter - the sweet spot is in road speeds between 60 and 80mph. The hand controls are ultra-light and all that's needed to cut speed is a tap on the lever to bring the 280mm discs into action. The impact of the Triple-yvps system is hard to detect. Once you keep the engine in the power above 6000 it's not an issue. The regular powervalve models offered a bit more power at the bottom end; the more sophisticated SPR'S version may broaden the torque lower in the revs, but I suspect it's more to do with enabling much more power to be released at the top for racing by using more radical porting. Either way the SPR is a lovely piece of kit for just staring at, or riding.
Alongside the TZR250 3MA parallel twin, the SPR V-twin is an armchair. Owen's example is almost the last of the series, the Sport Production (SP) from 1990 that is regarded as the holy grail, and is in effect a race bike with road equipment. Most of the 500s that were produced were raced, so unmolested road versions like this are rare, says Owen, making them highly collectable. The SP was acquired from Fastline Superbikes in 2015 for £8500, which makes it a bit of a bargain now. "I love it," says Owen. "It's a bit harsher with a more on-and-off power band, but it feels planted and you're more in control. The SP was so race focused, Honda protested." The SP also looks the business, just like it's come off the track. The Deltabox aluminium frame sparkles in the sunlight, setting off the red and white bodywork. The idea behind the parallel-twin engine's design was to reverse the conventional layout so the exhaust pipes exited from the rear, enabling the straight expansion chambers to create a stronger resonant signal for more power. The cylinders also have the rotary exhaust valves with electronic control to broaden the power, which is maxed out at 45bhp in restricted form for the domestic market. Owen says that his SP has received some jetting mods to the unusual forward facing Mikuni flat-slide carbs, and reckons his is good for 55bhp. Also unusual is the transmission. Power is taken from a gear in the middle of the 180-degree crankshaft to a layshaft that with two bob-weights doubles as a balancer. Thence another gear on the right side drives the clutch and six-speed cassette gearbox. Specification of the chassis is much the same as the earlier 3MA models, but with a wider 150 rear tyre on the 18-inch rim. Neat features include the racing-style chain adjusters only used on the SP.
I would have expected that with the expansion chambers passing under the seat and out of the fairing above the number plate, a measure of heat would be felt. But like the 3XVC, the 3MA at first feels soft to sit on and get accustomed to. It's when you fire up that the experience comes into sharp focus. This feels like a racer, despite coming with equipment such as a battery and tools hidden in the bowels of the fairing. With more trail, 94mm, the SP offers even more solid roadholding with a front end that feels almost locked to the road surface, yet with a steeper head angle of 25 degrees is easily flickable into corners. Perhaps the tuning had accentuated the sharpness of the power band, but I was also surprised at how smoothly the engine delivered power with the straight-cut drive gears singing up to the red line at 11,500rpm. Reports are that the 3MA parallel twins were less reliable than the V-twins, and after seeing the first of Jeff Ware's series (see page 84) it would be easy to concur. One theory behind this is that because the engine rotates backwards, the thrust of the piston during the downwards power stroke is to the front, so any clearance is accentuated on the exhaust port side. My stint on Owen's SP couldn't have been more fun, and I'd be inclined to prefer this bike to the V-twin simply because if you're going for something hard core, don't hold back. Until the factories offer road versions of Moto3 racers, which with 14,000rpm four-stroke 250cc engines developing up to 60bhp and propelling just 84kg are the nearest modern equivalent of the TZR250S, then we'll just have to hark back 30 years to a golden era of sports bikes - if you can find one, of course.