JerryThurstoncolumn
With regards to cylinders, when does the number stop being the most effective and become too many?
The necessity for a motorcycle engine to be compact and lightweight didn’t stop some manufacturers from exploiting multicylinder designs. It stands to reason really – more cylinders means more bangs in any given time, and hence more power. As with nearly all things, nobody agreed on the ideal, and, as a result, we’ve had some odd combinations and a lot of cylinders over the years.
Single cylinder is certainly the most simple, probably the cheapest to build and arguably the most successful of all motorcycle motors, with production capacities from 50cc up to Panther’s 650cc and everything in between and beyond, right from the first motorcycles to date.
Most popular has to be the 500cc single, a version of which has been in most manufacturers’ model lists for a century. Has there been a single year gone past where you could not go out and buy a 500 single from one manufacturer or another?
Here is a thing… If you subscribe to the theory that Hildebrand and Wolfmüller made the first production motorcycle around 1894/6, then the twin-cylinder machine beat the trusty single into production.
It’s tricky to find out which of the more known manufacturers adopted more than one cylinder first, but we do know that Norton won a TT in 1907 using a V-twin Peugeot motor and that Alfred Scott had his water-cooled two-stroke twins up and running in 1908.
Best of the lot? Everyone will have their own opinions – I’ll plump for any mid-1920s design with a big OHV, JAP V-twin (McEvoy by preference) but if sales success is any measure, I have to mention the Triumph parallel twins as perhaps the ultimate two-cylinder design.
According to some, the triple should be the best motorcycle cylinder designation of all. There are enough cylinders to be smooth and reasonably well balanced and, equally, few enough to be compact. While Moto Guzzi had a triple in the early 1930s, by all accounts it was hugely unreliable and was subsequently withdrawn from sale. Equally, the slightly later Scott three was less than a roaring success.
While many have built triples over the years, one particular machine tends to be lodged in people’s memory – the Triumph X-75 Hurricane, this helped no doubt by its, for the time, radical styling. The latest incarnation of the Triumph company still offers a triple, this one inline and taking the crown for the largest capacity production motorcycle engine, at 2.3 litres.
In the four-cylinder stakes, almost everybody has had a go at some time. Early adopters included FN in the very early 1900s. In the USA, Indian, Henderson
Ace and the lesser known Cleveland motorcycle companies all chose four in a line, most along the frame. Honourable mention goes to Ariel for doing it differently with the square four of 1931. This way of accommodating four pots is both neat and compact, and essentially two parallel twins geared together, although cooling the rear cylinders is a bit of a chore.
Later, with the advent of water-cooling, more builders jumped onto the four cylinder bandwagon, and the four cylinder concept exploded, giving us such things as near-200bhp, 500cc V-four two-stroke Grand Prix racers.
Six cylinders in a motorcycle frame starts to hint at manufacturers having an ego, waving their biggest and most complicated engines around in a display of dominance. Benelli started it in production terms in 1972 with its 750cc and 900cc six models. I wonder if Honda and the others felt threatened as a result? How else can you explain the Honda CBX6, with a wide 1050cc across the frame motor? Or Kawasaki upping the ante with a 1300cc version?
Eight and more… Here at the top of the multi-cylinder tree, I do wonder if there is any real advantage? Surely packing more into a small space just complicates things? Moto Guzzi perhaps came closest to making it work with their V-eight racer, boasting 72bhp from 500cc in 1955… Truly amazing. The others (maybe sensibly) have largely left this many cylinders alone – even the top-line manufacturers, who in the 1970s and 80s felt compelled to offer bigger motors with more cylinders to show who was top-dog, shied away from the eight. It’s been achieved by amateurs though – a pair of 1000cc Yamaha top ends grafted onto custom-made crankcases gave one Australian guy an alleged 335bhp to play with.
Lastly, you could completely dispense with conventional cylinders and use something else. Would you like an exhelicopter gas turbine, sir? For about $270,000 you can have one – at least you could a couple of years ago, though today the company appears to have disappeared.
More practical as an alternative to the conventional piston engine is the rotary motor. This is – at least theoretically – perfect for a motorcycle, being compact, free spinning and powerful. DKW got there in the 1970s followed by Suzuki and of course Norton who managed to make several different types of machine powered by their rotary motor, including the Interpol, Classic, Commander, the road-going F1 and the amazing racers, culminating in several British championships and powering Steve Hislop to TT glory in 1992.
“Six cylinders in a motorcycle frame starts to hint at manufacturers having an ego.”