Converting a 15hp to a 18 or 20?

[Tx.Fisher]

I have a 2003 15 hp tohatsu four stroke and was wondering if i could convert it to a 18hp or possibly a 20 hp. Is it possible to but a put a 20hp carburetor on the 15hp motor, or could I just remove a restrictor plate? The motor is a 15 B2 model, and some specifics on the motor are: Piston displacement is 328, Bore and Stroke is 59x60, and the weight is 121. Is this possible, or is it a stupid idea? Thanks for any info.

 

[Sea Rider]

Re: Converting a 15hp to a 18 or 20?

I have a 2003 15 hp tohatsu four stroke and was wondering if i could convert it to a 18hp or possibly a 20 hp. Is it possible to but a put a 20hp carburetor on the 15hp motor, or could I just remove a restrictor plate? The motor is a 15 B2 model, and some specifics on the motor are: Piston displacement is 328, Bore and Stroke is 59x60, and the weight is 121. Is this possible, or is it a stupid idea? Thanks for any info.

Both 15 & 20 HP four strokes have same 351 CC engines, so theorically could pass a 15 to 20, will need to check 20 carb parts and change/replace those of the 15 carb.

Happy Boating

 

[TOHATSU GURU]

Re: Converting a 15hp to a 18 or 20?

You can't turn a 15 B into a 20....You can turn it into an 18. You would need a variety of parts to do so. I think the parts alone would run about $500.00.