Throw lots of money at it or buy something with a larger engine.
Either way it will cost you lots of money.
The Honda Vision only has a tiny 50CC motor. If you start making major modifications to your Honda Vision there will be driveline parts experiencing stress much higher than they were designed. So you WILL have reliability issues.
You will also very quickly reach the limitations of the drive system and gearing. So more power won't make it very much faster. Just a little quicker to reach its top speed.
Your better choice would be to sell your Honda Vision and put the money from the sale towards something with a larger motor, maybe something in the 125CC range. This way you will have something that should be more reliable and have the speed you want.
