YAMAHA ‘LIGHTER CRANK WILL HELP THEM’
‘Rea is still able to push to the limit’
They will benefit from rules allowing a lighter crank – and therefore a lighter balancing shaft. They’ll also benefit from having a more efficient motorbike around the turns, thereby using less fuel. The R1 has always been known as a bike that carries more corner speed: enter quicker, carry speed and you don’t have to accelerate as hard on the exit.
Having said that, the bike runs a big balancing shaft because Yamaha have the ‘rocking couple’ effect going on with the crossplane crank (the engine has side-to-side vibrations more than up-and-down, meaning they need a balancing shaft that runs opposite to the out-of-balance crank).
Yamaha would love to profit from the new rules and lighten their crank and balancing shaft by 20%, giving them more top end but also more acceleration. At the moment, coming out of a corner, they have to spin all of that inertia and weight, which saps power from the bike.
However, because the rules state they still have to run standard rods, pistons pins and so on, the crank has to be a certain weight to balance the actual imbalance within the engine. The rods would be the main thing because they’re reasonably heavy.
How much can they lighten that crank and therefore the balance shaft? I’ve asked a lot of people and thought about it a lot. I reckon they’ll be able to lighten the crank by 10 to 12%. It will make a bit of difference.
Has Locatelli got an advantage? He’s had enough time to excel if he’s going to – he’ll still be there on occasions and we’ll have to see what he can do with his new crew chief, Tom O’Kane. Jonathan Rea… can he make the Yamaha work? I’d love to see that. He’s getting on in years but still seems able to push to the limit.