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  1. #1
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    More Power For My Vmax 225

    What can I do to get more power out of my Yamaha vmax 225 2 stroke short of putting a new motor on it?

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    #2
    Give us a call at 417 725-5746, or check out www.hydrotecmarine.com

    We have a few things that will help.

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    #3
    Heads are your best bet. Assuming this is a 3.1l?? What engine do you have? Be careful on the HPDI. CJ
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

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    #4
    CJ, can you expand on your caution of doing heads on an HPDI please?

  5. Iowa/Wisconsin/Hunting & Gun Lodge/Stroker Moderator Wags's Avatar
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    #5
    I would like to know also since this is my second HPDI Hydro-Tec motor with them on with no issues.
    LeaLea

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    #6
    Quote Originally Posted by CJ1 View Post
    Heads are your best bet. Assuming this is a 3.1l?? What engine do you have? Be careful on the HPDI. CJ
    Yep, no problem. Be sure the injectors are in good shape, esp #1 and 2. When you have the heads off inspect the cylinders for ANY irregular pitting ect on the tops of the pistons that may show detonation damage. Cut heads will make a problem worse. You are taking a wide window and narrowing it down as far as fuel quality and such. Run good, fresh premium preferably no alcohol. I am doing a 300hpdi in a couple of months and the injectors will be sent to Rich or Hydro tec for service depending on the owner preference and I will try to get him to at least pull #1 and #2 pistons to check the locating pin. [secretly that will be my chance to have him replace the stock pistons!] CJ
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

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    #7
    Quote Originally Posted by Wags View Post
    I would like to know also since this is my second HPDI Hydro-Tec motor with them on with no issues.
    And your engines were probably perfectly healthy, esp if Hydro Tec did the work. I have had people wanting me to do mods to their engines and they don't bother to tell me they have had or having issues with running, or their down on power and this is how they want to get it back. Or they don't want to run premium fuel because the know more than H/T. I have refused to do 4 different engines because of stuff like this. As the HPDI models get older this gets worse. Just didn't want the OP to lose a engine for stuff like this. CJ
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

  8. Iowa/Wisconsin/Hunting & Gun Lodge/Stroker Moderator Wags's Avatar
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    #8
    Quote Originally Posted by CJ1 View Post
    And your engines were probably perfectly healthy, esp if Hydro Tec did the work. I have had people wanting me to do mods to their engines and they don't bother to tell me they have had or having issues with running, or their down on power and this is how they want to get it back. Or they don't want to run premium fuel because the know more than H/T. I have refused to do 4 different engines because of stuff like this. As the HPDI models get older this gets worse. Just didn't want the OP to lose a engine for stuff like this. CJ
    Yes healthy for sure, but "be careful on the HPDI" needed a explanation like the one you just provided.
    LeaLea

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    #9
    IMO all big block HPDI's are prone to detonation. Particularly cylinder number 2, but all are vulnerable.

    If a head is shaved the compression ratio goes up and the chance of detonation is greater. I am presuming that Hydro-tech specifies the use gasoline with 91/93 octane if and when the heads are shaved. The HPDI's do not have a knock sensor installed to try and protect against detonation.

    Knowing what I do know about big block HPDI's, I would run 93 octane even if the heads have not been shaved. It is a bit more expensive yes, but it is a cheap insurance policy against detonation. And if there is greater carbon build up then there is a cheap solution for that. Detonation can be very expensive.

    Two more things to combat detonation. Make sure the motor is not over propped and don't stomp on the accelerator pedal resulting in the throttle being wide open for a short period of time while the engine RPM is still relatively low.

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    #10
    Good advice as usual Jethro. I hope you never buy a 4 stroke and leave us 2 strokers to fend for ourselves.
    You say don't stomp on the throttle, would that include coming out of the hole?

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    #11
    Great thread btw - I've got a HDPI V225TLR 2003 motor (just bought the boat) and she runs great. I was wondering about what to do's vs don't on the motor to make sure she gets me home and back. I put ethanol mix fuel in her b/c it's hard to find non ethanol fuel. I add the stabil and yamaha ring free additive to the fuel.

    Also, any advice on how to run or not run her would be helpful. Someone told me it's not a bad idea to get WOT every once in a while to knock out some of the potential carbon build up.

    Also - on the power upgrades on the 225 - what would you do to get the HP gain?
    2003 P@thfinder - 60Y VZ225 TLRB YAMI!

  12. Iowa/Wisconsin/Hunting & Gun Lodge/Stroker Moderator Wags's Avatar
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    #12
    Quote Originally Posted by jethro1 View Post
    I am presuming that Hydro-tech specifies the use gasoline with 91/93 octane if and when the heads are shaved.
    Yes sir they do for sure.
    LeaLea

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    #13
    Quote Originally Posted by jp10 View Post
    Good advice as usual Jethro. I hope you never buy a 4 stroke and leave us 2 strokers to fend for ourselves.
    You say don't stomp on the throttle, would that include coming out of the hole?
    Yes, exactly. I know that it will take away from a bit of the fun but hopefully the motor will live longer.

    Many, many years ago being young and stupid I owned a muscle car. Put street legal race slicks on it. Revved the motor to about 6 grand and dumped the clutch. The motor would bog down as it could not turn the tires over. Was not good for the motor at all. Not good for the clutch or drive train. Think I burned some valves and did some other damage.

    After owning two strokes for years and years jethro got a four stroke. Jethro loves him a four stroke. Problem with a four stroke is trying to start it when it is already running or forgetting to turn it off when pulling the boat out of the water.

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    #14
    This is the first I've heard about chronic detonation problems with HPDIs. Locator pins coming loose with the ring catching and taking out the top of the piston is not that uncommon.
    I believe Hydro Tech stated a minimum of midgrade gas with their heads. I would never do that. My Phase III always gets premium.

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    #15
    What would you classify 91 octane as? In Maryland I would say, 87 is base grade, 89 mid, 91 premium, 93 rare at marinas

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    #16
    "After owning two strokes for years and years jethro got a four stroke. Jethro loves him a four stroke. Problem with a four stroke is trying to start it when it is already running or forgetting to turn it off when pulling the boat out of the water."

    But the torque of a 2 stroke, the chain saw rumble of engine, a wiff of 2s oil in the morning, flipping off the tree huggers. Am I stirring up anything Jethro, or is it a lost cause?

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    #17
    Quote Originally Posted by jp10 View Post
    "After owning two strokes for years and years jethro got a four stroke. Jethro loves him a four stroke. Problem with a four stroke is trying to start it when it is already running or forgetting to turn it off when pulling the boat out of the water."

    But the torque of a 2 stroke, the chain saw rumble of engine, a wiff of 2s oil in the morning, flipping off the tree huggers. Am I stirring up anything Jethro, or is it a lost cause?
    Nope. It is all good.

    I had nothing but great luck with a Mercury carbureted two stroke model for over 30 years. I then had problem after problem with a Mercury EFI two stroke. Always was wondering if and when it was going to start when I went to turn the key. The four stroke Yamaha was like all of my EFI automobiles. It never crossed my mind about it starting or not. It always did. Then I could not even hear it. Only the sound of it peeing.

    Now I am going to use my two stroke chain saw tomorrow. Damn the smoke and the tree huggers. I just hope it will start.

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    #18
    Quote Originally Posted by Invader186S View Post
    This is the first I've heard about chronic detonation problems with HPDIs. Locator pins coming loose with the ring catching and taking out the top of the piston is not that uncommon.
    I believe Hydro Tech stated a minimum of midgrade gas with their heads. I would never do that. My Phase III always gets premium.
    Just because you can't see damage on the pistons does not mean it is not happening but lightly. I think it is just enough to rattle the pin till it loosens up. BRP had the same problem with their 800 e Tec sled engine. In a high load situation like their mountain sled they were coming apart in 1 to 2k miles. Regular sleds would go 10k before coming apart. Marine Is defiantly a high load situation. So good gas, warm it up before hammering on it and prop it just under the limiter. Don't lug it. Cj
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

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    #19
    Quote Originally Posted by Wags View Post
    Yes healthy for sure, but "be careful on the HPDI" needed a explanation like the one you just provided.
    I really wish I had enough $$$ to do some analasys on the #2 cylinder in these things, I believe they run a little lean or hotter than the others to cause so many failures on #2. Cj
    2002 X19 200HP OX66 HO Vmax,HPDI lower, it lives, thanks Hydro Tec.

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    #20
    Quote Originally Posted by CJ1 View Post
    I really wish I had enough $$$ to do some analasys on the #2 cylinder in these things, I believe they run a little lean or hotter than the others to cause so many failures on #2. Cj
    Yep, me also. Would be nice to put a thermocouple under each spark plug to see if the number two cylinder is running the hottest. Making it more prone to detonation than the other cylinders. Or maybe put an aftermarket knock sensor on each cylinder to see which knocks sooner than the others.

    For the life of me I don't understand Yamaha. High HP carburetted models running on the rich side came with a knock sensor. High HP EFI two strokes running on the rich side came with a knock sensor. Along comes the HPDI which runs much leaner for improved fuel economy and guess what? No knock sensor.

    Now guess which of the three models is most prone to detonation? Hint - it is not the two that have knock sensors and which run richer than the one that runs leaner.

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