I have a Yamaha 9.9 HP dating from 1990.
Someone told me that it was possible to modify it to a 15 HP. Does anybody knows about that ? What are the modifications to perform ?
I am asuming we are talking about a two stroke engine here. You will need a carb, reed block and cylinder head, you will also have to take the stopper off the advance to let the ignition advance further, cheers Davie
