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  1. #1
    wakewhornc's Avatar
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    GPR with 160-165psi Compression on Rebuilt Motor

    Here is the story, ended up having pwcengines rebuild my 1300PV motor cause I was tired of messing with it and couldnt argue with the 2 year warranty. Great turn around time took just over a week after I shipped my engine to get it back. Put it in and take it out Sunday, everything seemed ok so I started to break it in and again everything was fine up until 4-5000rpm then I could here detonation. So I let off and richened up the efi settings still same thing so I put it back on the trailer just got around to checking it out today and first thing I did was check compression and come to find out Im getting 160-165psi! No wonder it was pinging. My question is can I run 93 octane and be ok or is this too high of compression for premium? I know my gauge is accurate cause my SJ shows 175-180 on a stock milled head which is about right. I plan on calling pwcengines tomorrow and see if we can work something out should be as simple as a head swap I believe.


  2. #2
    Happily Self-Employed WFO's Avatar
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    I have run 180 psi on powervalve cylinders without problems... non-powervalve I would worry a bit. Also with that high compression, I would worry about #3... we always drop the rear cylinder around 10 psi to keep it together

    why is it that high? and did they sleeve or nikasil plate the cylinders?

  3. #3

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    Were you running 93 octane when you heard the detonation? If not then switch to 93 and see if its still there. You should be able to run 160-165 especially with stock timing on 93 octane.

  4. #4
    wakewhornc's Avatar
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    They sleeved the cylinders and I am running stock timing only mods I have are in the signature. I'm not looking for the fastest ski just reliable and quick. And I was running 87 octane when I heard it. Plan on just trying premium just to.see if it gets rid of it. On his website it says they machine all surfaces I'm thinking maybe they took just a bit too much off and the gasket he used (wsm?) Isn't quite as thick as oem. It my same block cause I put a couple scratches here and there just to keep track and they are all still there. I know sleeves are not the most popular way to go, but that's the way engines have been built for years, as long as its warmed up properly shouldn't have much of an issue

    ---------- Post added at 01:25 AM ---------- Previous post was at 01:23 AM ----------

    Quote Originally Posted by WFO View Post
    I have run 180 psi on powervalve cylinders without problems... non-powervalve I would worry a bit. Also with that high compression, I would worry about #3... we always drop the rear cylinder around 10 psi to keep it together

    why is it that high? and did they sleeve or nikasil plate the cylinders?
    180 on pump gas? And that's what I'm trying to figure out why is it so high?

  5. #5
    AquaGuy's Avatar
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    Hey wakewhornc, what does detonation sound like? I want to know for my ski.

  6. #6
    wakewhornc's Avatar
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    Quote Originally Posted by AquaGuy View Post
    Hey wakewhornc, what does detonation sound like? I want to know for my ski.
    Best I can describe it is just a loud ticking noise much louder then the rest of the engine and comes from under the seat not the exhaust behind you.

  7. #7
    160+ ? isnt that a little high for pump gas? I just bought r&d heads and am putting them on this weekend.

  8. #8

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    Quote Originally Posted by 00gp1200r View Post
    160+ ? isnt that a little high for pump gas? I just bought r&d heads and am putting them on this weekend.
    I have a friend that has an '05 1300 runs 165psi and a 4 degree timing key. Been running like that for about 5 years now on pump gas. I'm not saying do it....but its possible.

  9. #9
    Happily Self-Employed WFO's Avatar
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    Quote Originally Posted by wakewhornc View Post
    They sleeved the cylinders and I am running stock timing only mods I have are in the signature. I'm not looking for the fastest ski just reliable and quick. And I was running 87 octane when I heard it. Plan on just trying premium just to.see if it gets rid of it. On his website it says they machine all surfaces I'm thinking maybe they took just a bit too much off and the gasket he used (wsm?) Isn't quite as thick as oem. It my same block cause I put a couple scratches here and there just to keep track and they are all still there. I know sleeves are not the most popular way to go, but that's the way engines have been built for years, as long as its warmed up properly shouldn't have much of an issue

    ---------- Post added at 01:25 AM ---------- Previous post was at 01:23 AM ----------



    180 on pump gas? And that's what I'm trying to figure out why is it so high?
    check the squish

  10. #10
    wakewhornc's Avatar
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    Quote Originally Posted by WFO View Post
    check the squish
    Not sure how, figured I take all the fuel out that's in there now and throw some gas I have mixed up for the sj just ti see

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