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Thread: Building a 40 2 stroke Yamaha ?

  1. #21
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    Quote Originally Posted by Gone South View Post
    This…



    But also this… find you a set of 60hp carbs on that merc and you’ll see even more. Pair that with port matching your reed plate and you will know you did something. Easiest “bolt on” performance and bang for buck that you’ll be able to feel.
    yep! the difference between a stock 40 and a 60carbed ported merc is absolutely insane.

  2. #22
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    I appreciate all of the feedback. I Will have some deciding to do. I like the motor a lot. Just giving the merc guys a hard time. Grew up on Yamaha motors so it’s hard to switch. I’ll look into hydro-tec

  3. #23
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    HT 4095 Phase Kit 1995-2009 40hp Yamaha

    Looked up the hydro-tec kit, anybody ever have experience with these kits and the gains you can expect from them? It’s about a thousand dollars, if I’m gonna spend that much wondering if it would be worth taking it to a shop and having them do their work. I’m pretty handy, I could assemble the parts no problem but wondering if it’s worth the hassle or not.

  4. #24
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    Just get 50 carbs, a 50 tuner, and a shaved head. Don't get 70 carbs unless you have the motor ported and dont fet ported if you want reliability. All you need is the first sentence.

  5. #25
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    Unless you are looking to build it out as a hobby or you enjoy working on it, I would leave it stock. Try playing with props, jack plate, and weight for a few more MPH.

    Buy a higher HP/larger displacement motor if you really want bolt on performance. It will also be less expensive in the long run.

  6. #26
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    Quote Originally Posted by CreekBoy View Post
    HT 4095 Phase Kit 1995-2009 40hp Yamaha

    Looked up the hydro-tec kit, anybody ever have experience with these kits and the gains you can expect from them? It’s about a thousand dollars, if I’m gonna spend that much wondering if it would be worth taking it to a shop and having them do their work. I’m pretty handy, I could assemble the parts no problem but wondering if it’s worth the hassle or not.
    Ido, which is why I recommended it.

    It's not hard to do yourself just takes time and a lotta patience. First off do a compression check to see what you start with on all 3 cylinders. Take a 12mm socket, remove the head cover, take to machine shop, tell them to true up both sides ofthe head and shave 40 thou off the head cover to start. Buy new gaskets, for the size between the head and the block and the one between the head and the head cover, reassemble and do a compression check. Stock compression is about 110-115ish, if I recall. You'll likely wanna stick around 140ish maybe up to 150 psi. Any higher than that and you're gonna get yourself into a situation where you gotta run race fuel for the motor to run worth a flip. Anyway, if you reassemble and get 130psi take it back and shave off a few more. Shave off too much and the cylinder will strike the spark plug. Of course, that'd not be good.

    But the compression really only gets you good gains on the low end, not gonna do much for ya on the top end. Maybe a smidge, but not much.

    As for the carbs, the phase kit comes with main jets, and you send your carbs in. They're good bore them out to make the air intake bigger. More fuel going in, you need more air as well for more oxygen for the extra fuel to burn. However, if you diy and get 60/70 carbs they'll likely come with jets. I actually have a set of 60 carbs off my motor after I replaced with 90 carbs. If they'll bolt up we can work out a deal.

    The one part that the phase kit contains that you prolly don't wanna mess with is the tuner. Some people have experimented but why mess with it when HydroTec pretty much has it down to a science.

    By the time you procure a set of carbs (looking at $300+ unless you get lucky and find a deal), buy all the gaskets (possible you might not find them all in stock anywhere) and do the machine shop thing you prolly gonna be better off just buying the kit, but that's just me.

    Only you know how much your time is worth. You might can come out way cheaper doing DIY. Let us know.

    Sent from my SM-G970U using Tapatalk
    Last edited by willyworm; 06-12-2021 at 02:49 PM.
    [SIGPIC][/SIGPIC]
    Delta in a nutshell: Breeding grounds + small wetlands + big blocks of grass cover + predator removal + nesting structures + enough money to do the job= plenty of ducks to keep everyone smiling!

    "For those that will fight for it...FREEDOM...has a flavor the protected shall never know."
    -L/Cpl Edwin L. "Tim" Craft

  7. #27
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    Full disclosure... the rule of thumb for speed with outboards, or any internal combustion engine in general, there's no replacement for displacement. All this money and time is better spent on a Merc.

    Refer back to my last sentence on previous post.

    Sent from my SM-G970U using Tapatalk
    Last edited by willyworm; 06-12-2021 at 02:48 PM.
    [SIGPIC][/SIGPIC]
    Delta in a nutshell: Breeding grounds + small wetlands + big blocks of grass cover + predator removal + nesting structures + enough money to do the job= plenty of ducks to keep everyone smiling!

    "For those that will fight for it...FREEDOM...has a flavor the protected shall never know."
    -L/Cpl Edwin L. "Tim" Craft

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