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  1. #1
    PuprleNuprleGPR's Avatar
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    Why does Yamaha leave cavities in the pump shoes?

    A PPK is a good mod that a lot of people do to reduce cavitation. Why does yamaha go through the trouble to make these cavities in the pump shoe?


  2. #2
    "Hustler" Inkaddict's Avatar
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    Quote Originally Posted by PuprleNuprleGPR View Post
    A PPK is a good mod that a lot of people do to reduce cavitation. Why does yamaha go through the trouble to make these cavities in the pump shoe?
    I think I remember reading somewhere that they do that for pressure relief???

  3. #3
    PuprleNuprleGPR's Avatar
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    Well yea, but there must be more to it. On the GPR the tunnel is weak, but why on the rest of the line-up? I'm just trying to see what Yamaha was thinking when they put those voids in there and what we are hindering by sealing up those pumps

  4. #4
    Moderator OsideBill's Avatar
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    Quote Originally Posted by PuprleNuprleGPR View Post
    Well yea, but there must be more to it. On the GPR the tunnel is weak, but why on the rest of the line-up? I'm just trying to see what Yamaha was thinking when they put those voids in there and what we are hindering by sealing up those pumps
    I am sorry but reducing cavitation and improving hole shot does not equal a hindrance in performance. It costs more to make it solid, more in material costs, longer cycle times and quality.

  5. #5
    PuprleNuprleGPR's Avatar
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    Yea, I know that, but I was trying to look at it from Yamaha's POV. I didnt think that they would put in those voids just to save money.

    BTW - I though of this because I'm going to seal up the pump on our FX-HO with some silicone and 4200

  6. #6
    OLD # 7 IEGPR's Avatar
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    You bet they would, Everything is about money

  7. #7
    Moderator OsideBill's Avatar
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    It has a lot to do with quality. To make an accurate part repeatedly thick masses of material is not a good choice. Thinner wall sections tend to shrink less and warp less, which ends up requiring minimal secondary operations. Secondary operations cost money!!!

  8. #8
    PuprleNuprleGPR's Avatar
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    Quote Originally Posted by OsideBill View Post
    It has a lot to do with quality. To make an accurate part repeatedly thick masses of material is not a good choice. Thinner wall sections tend to shrink less and warp less, which ends up requiring minimal secondary operations. Secondary operations cost money!!!
    Gotcha. Thanks for the info

  9. #9
    tiffy's Avatar
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    ppk

    i had the same question but that really does make sense

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