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Yeah, interesting! It seems the 3 cyl engine is becoming much more popular these days, notably in the car world too, with VW, BMW & others all either making one already or about to introduce one. The attraction there appears to be efficiency, more torque at lower revs & lower friction losses & still smooth in operation (with a balance shaft as dictated by mounting arrangements).

Besides my Legend, I'm ahead of the game here with my car a 3 cyl 1.0l Suzuki ;)

I suppose what may be innovative with this Yamaha is the crossplane crank. They aren't giving details as yet but I'm assuming they aren't dumb enough to cod us into thinking a 120deg crank is innovative (or crossplane). So that suggests 90deg crank pins - imagine a 'T' shape, say, with the outer two cylinders making the cross & the middle one the other bit. Their engine looks like it has a balance shaft in the same position as ours. This would need to balance (as Triumph) the side to side rocking couple (1 side heading for TDC, the other BDC), plus a bit of extra metal in the middle to counter balance the up/down of the middle cyl.

The Yamaha XS750/850 (a 120deg triple) didn't have a balance shaft because the engine was rubber mounted. But as virtually all modern bikes (of a size) rigidly mount the motor in order to use it as a stressed member & save frame weight, they all need a balance shaft. (A lot more are being used in fours too for similar reasons.) So there's little more effort involved to counter balance a crossplane. (Or maybe this middle cyl can be looked after on the crankshaft itself?)

It could be Yamaha are aiming for some supposed traction advantage, ultimately in a 675cc triple supersport class, mirroring their M1/R1 fours.

But in road bikes, the crossplane may be just intended to give an extra dollop of 'character', one up on Triumph even, with their inherent offbeat firing & exhaust note. And it'll have the nice torque/power character of triples & better fuel economy compared to the usual fours from Japan.

Of course 'crossplane' also helps Yamaha to avoid the charge of simply copying what Triumph are doing.
 

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...& better fuel economy compared to the usual fours from Japan.
Yeah I know what you mean there. When I had to retake my bike test after coming to Germany one of my riding lessons was a 200 kilometer Autobahn ride and I had to fill it up halfway!

That was a Honda 650 4 cylinder, (no idea which model but it was black if that's any indication ;) ), and the engine was really screaming at about 130kmh. They're fast low down but once you get upto speed there's nothing left. I was always looking for another gear :confused:.
 
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