25 yamaha 3 cylinder mods

[jastampke]

I have a 25 yamaha 3 cylinder. I have read that these motors can be beefed up to a 30 or 35 hp. Is that true? I know they can be modded, with bigger carbs and such. I am really trying to find out if i can just do a couple simple things to make it like a stock 30 or 35..

 

[gm280]

Re: 25 yamaha 3 cylinder mods

I have a 25 yamaha 3 cylinder. I have read that these motors can be beefed up to a 30 or 35 hp. Is that true? I know they can be modded, with bigger carbs and such. I am really trying to find out if i can just do a couple simple things to make it like a stock 30 or 35..

I see this type question asked over and over and over and even had those same questions myself before understand the true answers. I can't say I know anything about your O/B because I've never own a 25HP Yamaha O/B. But one sure fired way to get 35HP from a 25HP O/B is to disconnect the fuel line the steering controls if it has any, And remove the 25HP engine and then sell it and purchase a 35HP O/B and reinstall. You will then surely have 35HP and be the cheapest route too...

 

[jastampke]

Re: 25 yamaha 3 cylinder mods

well i guess you didnt answer my question at all. you could have kept that to yourself since you know nothing about the subject we speak of. I am guessing that you probably have nothing better to do with your morning but to comment needlessly on threads that you know nothing about. So please go sit back on your couch and scratch yourself. nobody likes a smart*****

 

[gm280]

Re: 25 yamaha 3 cylinder mods

I guess with you disgruntle attitude you will certainly get a lot more responses now... I was merely trying to explain the usual answer to your need for more HP. So many have come before you with their need to create more HP from their O/B's as well and the true facts are, it would take more money then selling your engine off your engine and buying a higher HP one. So it wasn't a smart*** answer but a pure honest answer. Have a good day though...

 

[99yam40]

Re: 25 yamaha 3 cylinder mods

In my opinion you will get better responses on a OB racing forum as they are the ones that modify motors

 

[boscoe99]

Re: 25 yamaha 3 cylinder mods

The whole world is looking for something for nothing.

 

[TwoRivers]

Re: 25 yamaha 3 cylinder mods

I can't answer your questions about turning a 25hp yamaha to a 30+.
I do however, consider it a legitimate question.
In my case I have a 25hp Nissan. The Nissan/Tohatsu (2 stroke) 25 and 30hp models use the same powerhead, pistons, carb, etc.
The same is true for the Nissan/Tohatsu 9.9 and 15hp two strokes.
It's an easy conversion from 25 to 30 or 9.9 to 15 with these engines (not that I think it makes a lot of difference).
The Nissan/Tohatsu update isn't free. It costs about $7.
Keep searching, the truth is out there somewhere.

 

[Capt Ken]

Re: 25 yamaha 3 cylinder mods

With the attitude it's probably best he finds his answers elsewhere.

 

[boscoe99]

Re: 25 yamaha 3 cylinder mods

The OP first wants to know if the motor can be modified. Of course it can. Given enough time and money anything is possible.

He then qualifies it by saying he wants the mod to be simple.

Go to the Yamaha parts catalog and look at all of the differences between a three cylinder 25 HP Yamaha and a three cylinder 30 HP Yamaha. Whatever the differences are, remove the 25 HP parts and install the 30 HP parts. Maybe a thousand bucks or so will do it.

 

[rivvy]

Re: 25 yamaha 3 cylinder mods

I believe these are 30hp motors with different carbs/jetting.Go to tinboats.net and PM turbotodd he is will know which modifications are nescessary.

 

[Pas Bon]

Re: 25 yamaha 3 cylinder mods

I have always understood the the 3 cylinder Yamaha could be tweaked to pump out a few more horses. Just ask around a duck hunting forum in AR where there is a 25 hp max for public land!

 

[Faztbullet]

Re: 25 yamaha 3 cylinder mods

Just change carbs to the 30hp and you will have a 30.....

 

[deejaycee_2000]

Re: 25 yamaha 3 cylinder mods

I use to race the trip yamaha's and suzuki's 25/30hp motors, yes there is a lot you can do to this motor ..... you can put in oversize piston, change the reeds, remove the rev limiter, port it, change exhaust, shave the head ... the possibilities are endless .... but it will reduce the lifespan of the motor and it also does't come cheap either .... I use to get 75km/h out of my trip yamaha

 

[junkyardwarrior]

Re: 25 yamaha 3 cylinder mods

How much are you willing to spend?

There's guys who have made ~80 HP out of the 25 triple.

Call Hydrotec marine out of Nixa, MO. They have a website.

Popular motor out in Arkansas. Most of the duck hunters use them on public lands, where 25hp is the restriction, and almost NOBODY runs a true 25 HP motor (they're all 30+). Some are close to 60 mph now out of the Mega 25's and the triples and the 'zuke DT25 (with a few mods). The hull has a lot to do with it but it's generally "easier" to mod the motor. Hull modification is sort of a black art, and no I don't know anything about it. I used to have a Yamaha 25 triple. Same block as a 30. Didn't need to hang onto it once I bought the 4 stroke and put it on eBay. Some guy out of Arkansas offered me twice what I was asking for it, and of course I didn't bat an eye..closed the auction and he drove 9 1/2 hours to pick it up.

The arkansas game & fish is starting to police those public lands more & more.....from what I hear. I can't imagine a load of 50 or more jon boats going 40+ MPH down a "ditch" at 4:30 AM. No wonder half of the boats come back to the ramp with a hickey or two.