tohatsu 25 hp 4 stroke... upgrade -> 30 hp

[swboat]

I heard that you can remove the restrictor plate on a 25 hp to get 30 hp.<br /><br />What information does anybody have to confirm or deny this rumor/truth?<br /><br />Thanks,<br />Art

 

[Manxman]

Re: tohatsu 25 hp 4 stroke... upgrade -> 30 hp

I was told by a dealer over here that the main jets need to be replaced as well.

 

[buckeye_sean]

Re: tohatsu 25 hp 4 stroke... upgrade -> 30 hp

Not to highjack this thread, but I was also just wondering about this same thing - although for my 9.9. <br /><br />Seems in my year of Nissan they also made a 9.9hp, 12hp, & 15hp with the same bore. So I imagine the differnce is all in the carb right?<br /><br />If this is the case is it merely a restrictor plate issue, or would I need a whole new carb?

 

[phatmanmike]

Re: tohatsu 25 hp 4 stroke... upgrade -> 30 hp

its not just fuel, it also has a lot to do with the exhaust(lower units and mid section) <br />bigger exhaust=bigger hp<br /><br />and keep in mind that these motors do not HAVE to put out what the cowl hood says, i.e, 9.9, 12, 15 whatever... by certification standards, they only need to bee within 10%.<br /><br />ive seen some of the yamaha's use restricter plates, but in that case, it simply limits the top end, how high it can rev, so you wont ever feel these extra 3 or 5 hp unless your wide open<br /><br />99% of the time, its easie(and cheeper) to simply sell what you have and buy a bigger motor.<br /><br />sorry, but these arent for 302's. its almost impossible to "soup up" a tinny lil 10 cubic inch 2 stroke outboard without heavy /extensive(expensive) modifications.<br /><br />m ikey

 

[swboat]

Re: tohatsu 25 hp 4 stroke... upgrade -> 30 hp

Well, due to emissions, restricting the exhaust is no longer an option for newer engines. Most RPM limiting will have to come from the carburetor.<br /><br />I'm just wondering if it's really just the restrictor plate on the 25 4-stroke that's the difference from a 30.<br /><br />Yeah, I have the same question with the 9.9 4-stroke as well say versus the 15. The engine specs are the same except that the 15 goes 500 rpm higher. Could this just be a restrictor plate in the 9.9 too?