No-one would disagree that a lot of Fours were sold.
But if you look back over Yams history, they have sold a mighty lot of twins ?.
And given they were for a while the worlds largest motorcycle manufacturer, and twins of various types made up a fair bit of that production, thats a lot of twins ? Lot of them were 2 strokes, of course.
In fact, when you think about it, Nortons only made twins for 25 years, in relatively small numbers ?, and Yam have now been making them for 50+ years. Wonder what % of each are still on the road - if that is in any way relevant ?!
This reminds a bit of the discussion about the best selling bike of all time.
It was pointed out that the Honda postie bike had sold more (total) than the entire output of the british motorcycle industry all through history. And the H*nda Cub and SuperCub (stepthrough scootery things) provided basic transport in about 75% of the countries on earth - and had sold tens of MILLIONS of them. Bread and butter, bread, and butter. To do better things with...
Well, its seems they are still doing it...
According to the latest issue of AMCN, Yamaha has announced they are dropping their R1/M1 inline 4 Superbike/Moto GP mills in favour of triples![Having checked out Triumph mills].
Although, strangely they claim they will stay true to the 'crossplane' crankshaft configuration.
So that is 90`- 90` X 4 = 360`...A cross plane triple? Think Mercedes tri-star..
& a 120` triple is 120 X 3 = 360`...same as virtually every triple except for Laverda's off beat 180`job...
Nortons, Triumphs, BSAs... have the same gene favoring them to survive, they did not evolve much while they were produced which means spares from one year can be used on a different year's model. Aftermarket suppliers don't have to make a whole slew of different parts and they are very simple machines, built with simple tools without too much use of materials that have not withsood the test of time, namely plastics. The biggest problem facing us is the dreaded fiberglass desease. Now consider any of the early bikes from Japan, they made heavy use of plastics from the time they were exported in large numbers, try to find a good set or a new set of leg shields for a Honda cub or a headlight shell for a Yamaha BIg Bear, good luck.
The only thing that will save them will be 3D printers and easy to get cad files.