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I have a 1996 Yamaha 40hp motor that I am wanting to make a little faster. This is a two cylinder motor I was told I could put 60hp jetts in the carbs and it would basically be a 60hp at that point. Does anyone know if this is true and if not what are my options?
no,60 carbs would get some more hp.............. 60hp carbs
Thanks I don't want to build a race motor I just want a little more top end out of my boat. It's a 14' tracker style fishing boat not a race boat by any means. Any other suggestions like prop size and pitch would be greatly appreciated.
How heavy is the boat? If you haven't already get a tach of some sort, very helpful when prop tuning. What prop have you got just now? I think I'm right in saying you have a solid steel crank in that engine, so can rev as high as you like. You could shave the head for more compression, as Fred says 60hp carbs will go on, maybe 55hp as well.
You should be able to get carbon fibre reeds for it, either boyesen or CCM.
I'm not sure on the prop size I will have to take it off and see. I will look into a set of reeds also. Is there any drawbacks when it comes to shaving the head and will I need to do anything else to the motor to put it back together after I have it shaved?
Changing props is the best way to gain speed, much cheaper as well. A decent chopper or cleaver prop, lift the engine up on the transom and you'll get a lot more speed. If you have an aluminium prop just now simply changing to stainless will gain you some performance all round.
You will want a GPS and tacho to help tuning though. If you shave the head a lot you will have to run higher octane fuel, I'm sure someone on here will know how much you can take off and still run standard pump fuel. You might want a new head gasket depending on the age/condition of your motor. It can't hurt to replace it if you're taking the head off anyway. If you have a compression tester do a check on each cylinder, you want them pretty much equal.