Increasing boat Performance?

Question

Motorbikes can have their cylinders bored to increase performance as well as adding exhausts, what can one do to increase power/performance on an outboard short of replacing the engine with a more powerful one?

B

Answer 1

change the prop out.  Stainless steel it the way to go.

Answer 2

You can bore out the cylinder head, on only a few cylinders such as an outboard, it will be costly, and will not give you a good return on performance (cars have 8 cylinders, a lot more displacement on more cylinders from the over bore), it's more efficient, economical, and gives a larger performance gain in return to just "re-power" the hull with a larger motor, especially on an outboard, since the object of it is to make re-powering easier than an inboard engine, as well as save space.

Answer 3

you can bore out the cylinders and put in larger pistons just like on a motor bike... you will also want to put in a new exhaust manifold to handle the additional output. if you decide to do this, you may want to change out your reeds... aluminum comes standard from the factory and they can break under the high pressure boring the cylinders will make. i would change them out with boysen reeds. they are fiberglass and when or if the break they will shatter thus not risking ruining the head... i have seen the aluminum reed stick right into he wall of a power-head....

Answer 4

I would not recommend boring out your cylinders on an outboard. Too many things can go wrong in the process. I would experiment with different props first. If you're using a 3 blade prop, try a 4 blade. You may have to adjust the pitch. Also, I'd use an aluminum prop, s/s props can are much more likely to damage drive shafts if you ever hit something.