mariner 30hp performance upgrade

[notorious]

I have a late 80's early 90's Mariner 30hp oil injection model, im told its actualy made by yamaha.
i want to increase my power and im told i have to change my carburetor and reed valves and get the head skimmed and ported.
i have just bought a 10x13" pitch stainless prop and it gives me a good top end but its not fast enough on to the plane, i want it to punch! at least quicker than it currently is.
i dont want to change the engine to a 40hp because of weight increase, i have this engine on a 2.9 meter rib.
i can't find a serial number on my carb without taking it off and my engine serial number plate is damaged, all there is Tieki and Japan, does this help?
Can anybody help me find a new larger carburetor, is this the right thing to do??
can anybody help????????? can i increase my hp?????????

[mcyama]

Notorious, be happy!! Let's figure out what you have. Yamaha U.S. never had a 30 hp 2 cylinder with oil injection in this market. So you say you have one carb?? Can you locate on the carb mounting flange the model number, it would be very small. It should look like this (689) (692) (6j8) or something of that sort. Second look at the cylinder head for the same series. You could always post some pic's. Mercury Outboards built a very nice and fast chopper prop for there 25 hp. You may want to consult with your local Yamaha dealer and ask him to tell you wether it is a 30 cid or a 24 cid. Hopefully you have the larger. You can also simply change venturi size and fuel requirments of the carb you have. Yes your friends have told you what you need to do toincrease performance of your unit. Happy Holidays Martin

[notorious]

Hi Martin
Thanks for your post, yes its a single carb, ill get down this week and take a look at the flange for numbers.
I will take some pictures, many thanks for your help.
Regards
Alex