First ride: Honda CB1100 RS & EX review

The RS takes the same basic frame and motor as the classic EX and hits it with a sports hammer

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Simon Hargreaves's picture
Submitted by Simon Hargreaves on Mon, 10/04/2017 - 15:54

Honda CB1100 RS

WHY did the chicken cross the race track?

To get On-da other side.

It’s funny – or not – what goes through your mind when you’re up in the air, yet with both wheels in contact with the ground. That might be because it’s not every day you’re riding round a banked oval speed circuit in Spain, now converted into a chicken farm, on a brand new Honda.

This is the launch of the CB1100 RS and CB1100 EX, and we’re at the Autodromo de Sitges Terramar just outside Barcelona. The track was built way back in 1922, raced on only a few times, then fully abandoned in the 1950s – since when it’s been a chicken farm, for cluck’s sake. But the dramatic concrete banking is still intact; crumbling, cratered and mossy, but navigable by motorcycle. With banking at each end that goes all the way up to vertical, it’s like a cross between a racetrack and a wall of death. So it’s not about top speed and lap times round here, it’s about atmosphere.

Which also sums up Honda’s two new CB1100s.

For a company that kickstarted the modern superbike with the 1969 CB750, it’s taken Honda a long time to revisit their history. When other Japanese factories were repackaging old air-cooled engine technology with a retro twist in the 1990s, Honda built the resolutely liquid-cooled CB1000 and CB1300. It was only a few years ago, in 2013, that they succumbed to fashion and released the air-cooled CB1100 – perfectly timed to face extinction from Euro 4 emissions legislation.

Before diving into the whys and wherefores of the RS (above) and EX (below), it’s worth detouring to talk air-cooling; seeing as Yamaha have just dropped the air-cooled XJR1300 Racer from their line-up, isn’t the writing on the wall for big-bore air-cooling?

Not with the CBs; Euro 4 regs were factored into the engine design brief from the start. And it depends how much power you want your motor to make. With the bottom end and stroke of the CB11’s motor lifted from the liquid-cooled CB1300 (itself based on the CBR1000F motor from 1987), and with deeply finned, air-cooled barrels slimmed to bring capacity back to 1140cc, the 1100RS and EX sneak under the Euro 4 wire by careful design of air and oil cooling paths (say, the hot spots around the spark plugs and exhaust valves), and by not being hugely powerful in the first place.

It works like this: in the old, air-cooled days you’d rely on the flow of air, oil and fuel, plus cam and ignition timing, to control combustion and engine temperatures – and when there were few limits on pollutants in the exhaust gas, you could balance them and tune them any way you liked.

But to meet Euro 4, the catalyst in the exhaust has to work cleanly and efficiently under all conditions, from cold start on a cold day to full throttle on a hot day, within a narrow temperature window. So controlling engine temperature becomes critical – and when you’re forced to be parsimonious with fuel (to keep emissions down), but you want to keep air-cooling because it looks cool (ironically), the only way to keep exhaust gas clean enough is to tune – or de-tune – cam and ignition timing…

… Which means your engine inevitably makes less power at lower revs. Or, in the CB1100s’ case, 88bhp at 7500rpm and 69 lb.ft at 5500rpm (and that’s why 1987’s liquid-cooled 998cc CBR1000F version of the CB1100’s motor made a measured 120bhp at 9800rpm... 30 years ago).

Anyway, so here we are with the 2017, air-(and oil-)cooled, Euro 4-friendly CB1100RS and EX. Both are updated spin-offs of the 2013 CB1100 – which was a bit vanilla, unsure if it was a full retro or something more modern. Thus Honda pitch the new bikes two ways, to satisfy both camps. The EX is a retro-ised, wire-spoked, twin silencer version; the RS is a sportified, semi-café racer.

Both bikes have the same updates over the outgoing CB1100s: bigger, 17 litre tanks, new suspension, new wheels, a new, lighter slipper clutch, redesigned rear mudguard and LED tail light, LED headlight, shorter, lighter silencers, a redesigned single intake manifold, and a longer sidestand.

And both bikes also have updates specific to themselves. The EX’s 18in wheels get fewer, longer wire spokes with better plating mated to smaller ally hubs and new Dual Bending Valve Showa forks. The EX is five kilos lighter than the previous EX, at 255kg.

Meanwhile the RS has more significant changes; it’s a new bike. It takes the same basic frame and motor as the classic EX and hits it with a sports hammer: cast 17in ally wheels, radial Tokicos on 310mm discs (instead of the EX’s 296mm), fat 43mm Showa Dual Bending Valve forks with extra damping, twin Showa piggy-back shocks, a fat aluminium swingarm, flatter handlebars and a blacked-out look to engine and chassis. Steering geometry is sharper; more fork offset gives less trail, steering angle is a degree steeper and wheelbase 5mm shorter. Weight is 252kg.

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