When the scoot isn't gaining speed (accelerating) it means that all the power that the engine is making is used to fight airdrag and roll frictions.
Because of this, there is no power left to increase the kinetic energy (=speed) of the bike.
If the gearing is too short, the variator comes to the end of its range. At this point the engine tries to increase revs, and so it does, but unfortunately after the maximum HP rpm, the power falls rapidly (bad cylinder scavenging). 2000-3000 rpm over the maximum power rpm, an 20hp racing setup will make only ex.:10hp. A scoot with 10hp isn't very fast.
So we try to keep the rpm at maximum power, this way it will stop gaining speed when the opposing "power" of the airdrag matches the engine power. Well, would be more correct talking about forces, but it will do...
The airdrag goes up by square (^2). This is why a scoot does not have a constant acceleration until top speed (if it would have an constant acceleration this means that the drag force would be constant or none, so it would constantly accelerate until near speed of light).
If a scoot with 20hp makes 150km/h, to go 300km/h it would need 80hp.
Because of this, there is no power left to increase the kinetic energy (=speed) of the bike.
If the gearing is too short, the variator comes to the end of its range. At this point the engine tries to increase revs, and so it does, but unfortunately after the maximum HP rpm, the power falls rapidly (bad cylinder scavenging). 2000-3000 rpm over the maximum power rpm, an 20hp racing setup will make only ex.:10hp. A scoot with 10hp isn't very fast.
So we try to keep the rpm at maximum power, this way it will stop gaining speed when the opposing "power" of the airdrag matches the engine power. Well, would be more correct talking about forces, but it will do...
The airdrag goes up by square (^2). This is why a scoot does not have a constant acceleration until top speed (if it would have an constant acceleration this means that the drag force would be constant or none, so it would constantly accelerate until near speed of light).
If a scoot with 20hp makes 150km/h, to go 300km/h it would need 80hp.