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  1. #71
    radio-active's Avatar
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    I've been staying out of this discussion as best I can because I do work at Polaris (never hidden that fact), but I am reading it with great interest.

    But let me just comment briefly -- the 2 liter 4 cyl Prostar engine in Slingshot is a beast. And it would not fit in a PWC hull.

  2. #72
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by Mentzel View Post
    The SVHO engine is not reliable as far as supercharger goes. ... you will be swearing at the factory unit sometime soon...
    The clutch is not the engine. Replace the clutch, ride on. Takes a couple of hours to do the swap. I have already replaced one. Not a big deal.

    200+ running hours between clutch replacements, I am fine with that.

    If the revised 2021 Yamaha clutch turns out to have more longevity, even better.

    With a 2-stroke those same 200 running hours would be a complete engine replacement. A lot more cost, more downtime, more wrench time.

    I can keep a couple of spare supercharger clutches on a small shelf. A couple of spare 1200 Polaris engines would require a pallet.

  3. #73
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by radio-active View Post
    ... the 2 liter 4 cyl Prostar engine in Slingshot is a beast.

    And it would not fit in a PWC hull.
    Does that mean it physically is too wide/tall to fit inside the hull?

    One thing that PWC engines need is a very low crank centerline, relative to the very bottom outside surface of the engine. Does the new 2 liters Polaris engine have a low crank centerline?

    Years ago a GH member converted a Mercury V6 2-stroke drag race outboard engine to fit into a Seadoo hull. He had to do modifications to allow the V6 to lay down in the hull. When he was done it was ‘too fast’ for the hull he chose. I think it was this guy. IIRC the engine was pulled out and he planned to put it in a different hull (GPR?). I don’t know if that second project ever finished.


  4. #74
    Quote Originally Posted by K447 View Post
    The clutch is not the engine. Replace the clutch, ride on. Takes a couple of hours to do the swap. I have already replaced one. Not a big deal.

    200+ running hours between clutch replacements, I am fine with that.

    If the revised 2021 Yamaha clutch turns out to have more longevity, even better.

    With a 2-stroke those same 200 running hours would be a complete engine replacement. A lot more cost, more downtime, more wrench time.

    I can keep a couple of spare supercharger clutches on a small shelf. A couple of spare 1200 Polaris engines would require a pallet.
    I have 0 confidence the new revised clutch will be any better. The supercharger shaft need to be addressed as well....

  5. #75
    radio-active's Avatar
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    I won't get into specifics, but suffice to say it's designed to mate with an automotive type transmission.

    You can find plenty of images on line to draw your own conclusions regarding the crank centerline, size, etc.

  6. #76
    sdlvx's Avatar
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    Quote Originally Posted by K447 View Post
    The clutch is not the engine. Replace the clutch, ride on. Takes a couple of hours to do the swap. I have already replaced one. Not a big deal.

    200+ running hours between clutch replacements, I am fine with that.

    If the revised 2021 Yamaha clutch turns out to have more longevity, even better.

    With a 2-stroke those same 200 running hours would be a complete engine replacement. A lot more cost, more downtime, more wrench time.

    I can keep a couple of spare supercharger clutches on a small shelf. A couple of spare 1200 Polaris engines would require a pallet.
    It's awfully expensive though.
    https://www.4-tecperformance.com/ind...ex&cPath=2_163

    It takes a few hours to slap a new top end of a two stroke, and if you don't have nikasil you can hone it out in 30 minutes and be good to go. Only about $300 for a 750 top end rebuild kit, including gaskets. You also have to worry about those superchargers exploding and throwing bits into your engine.

    Quote Originally Posted by radio-active View Post
    I won't get into specifics, but suffice to say it's designed to mate with an automotive type transmission.

    You can find plenty of images on line to draw your own conclusions regarding the crank centerline, size, etc.
    Dang that's a huge bummer. I looked at some pictures but couldn't really see that, but I couldn't really find good pictures. That would make a complete beast of a ski. Is it a problem with all Pro-Star engines? Or could they do the same to the smaller ones and add a cylinder or two? Then again you are probably in major NDAs so if you can't respond it's fine, don't want to get you in trouble. Looking at the other ones, they all look like they're slanted and don't sit straight up and down. Not sure if that could actually work for a PWC.

    Almost sounds like the Pro-Stars are only meant for transmissions and Polaris would need to adapt a snowmobile engine, which they don't really have any good 4 stroke engines for AFAIK.

    Slanted Pro-Star



    Yamaha TR-1
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  7. #77
    radio-active's Avatar
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    Well obviously most are designed to have a CVT clutch on the output shaft, as basically everything Polaris makes (except Slingshot & Indian) uses CVTs.

    It's not a "problem" for those applications.

  8. #78
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by sdlvx View Post
    It's awfully expensive though.
    https://www.4-tecperformance.com/ind...ex&cPath=2_163

    It takes a few hours to slap a new top end on a two stroke, and if you don't have nikasil you can hone it out in 30 minutes and be good to go. Only about $300 for a 750 top end rebuild kit, including gaskets.

    You also have to worry about those superchargers exploding and throwing bits into your engine.
    I do not worry about my Yamaha SVHO supercharger ‘exploding’. Not at all. If anything, that is/was mostly a Seadoo thing.

    I have never owned a 750 Polaris. All of mine were 1200’s, and all but one was Ficht. Almost every time I needed to do an engine rebuild, it was the bottom end too.

    The few times I got away with refreshing a single cylinder (overbore+new piston+gaskets+whatever), the cost was probably close to $300 - per cylinder. Plus the wrenching time, which takes away from riding time. And then I still have to go through the break-in process, which is annoying.

    Paying $400 something every four years for a Yamaha clutch seems like a reasonable running expense. Way less than 300 hours of 2-stroke engine rebuilding would cost me.

  9. #79
    Quote Originally Posted by K447 View Post
    I do not worry about my Yamaha SVHO supercharger ‘exploding’. Not at all. If anything, that is/was mostly a Seadoo thing.

    I have never owned a 750 Polaris. All of mine were 1200’s, and all but one was Ficht. Almost every time I needed to do an engine rebuild, it was the bottom end too.

    The few times I got away with refreshing a single cylinder (overbore+new piston+gaskets+whatever), the cost was probably close to $300 - per cylinder. Plus the wrenching time, which takes away from riding time. And then I still have to go through the break-in process, which is annoying.

    Paying $400 something every four years for a Yamaha clutch seems like a reasonable running expense. Way less than 300 hours of 2-stroke engine rebuilding would cost me.
    Well you should worry because its just a matter of time before the shaft breaks and takes out the whole thing. Two for me this year....

  10. #80
    Click avatar for tech links/info K447's Avatar
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    Quote Originally Posted by OutlawGPR View Post
    ... its just a matter of time before the shaft breaks and takes out the whole thing.

    Two for me this year....
    How is worry going to help anything?

    I am not seeing frequent reports of problems with the actual Yamaha SVHO supercharger or the shaft. A few breakages here and there but not many. Far more clutch slippage reports than anything else.

    I suppose if I wanted to be proactive I could inventory a spare supercharger and spare intercooler. Stock used units with low hours are generally available. And then wait how long for a possible failure?

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