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  1. #1
    christian gpr's Avatar
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    Compression question

    Just did a compression test on my gp130r -04 with 55hours at sea level. I got on nr1-115 nr2-103 nr3 115. This was at wot with a battery charger, cold engine and two plugs in. I`m worried about nr2. What could be the problem?


  2. #2
    Hydrotoys's Avatar
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    Stock heads use different dome sizes....Ride more, worry less.

  3. #3
    Happily Self-Employed WFO's Avatar
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    did you check #2 first?

  4. #4
    christian gpr's Avatar
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    No I checked nr1 first. The reason I did the test is that I have just recived a stock milled head to 150psi from Protec and I wanted to se that every thing was ok first. Is it ok to put the new one on?

  5. #5
    Pistonwash's Avatar
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    Christian,
    Go ahead and pull the head and inspect your cylinders, if there is no scarring/scoring of the cylinder walls, I would suspect the pressure gauge is fried. Good luck, and let us know what you find.

  6. #6
    Happily Self-Employed WFO's Avatar
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    You will usually get a lower reading on the first cyl you check...

  7. #7
    christian gpr's Avatar
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    Pistonwash I also suspect the gauge is not the best but I did the test twice, first time without a battery charger, engine hot and no sparkplugs, the results were similar nr1-110 nr2-95 nr3-110.

  8. #8
    Pistonwash's Avatar
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    Pull the head and inspect the cylinder walls. This is the only true way of seeing any damage. Post pictures if you can and we'll stick our collective heads in your ski.

  9. #9
    christian gpr's Avatar
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    Thank you all for the help I will pull the head in the morning (it`s evening here) and let you know what I find. Since I got you on the line I also have another question. My next mod after the head is the Jetworks mod. Do I have to have the free flow(I don`t realy want the higher noise)? My mods this far are: Efi, Riva Boysen reedstuffers, Power filter, Trim tabs, R&D intake grate, Skat 13*19 and 14*20 Dplate+chip,PPK,R&D sponsons, Jettrim seat cover.A 150psi head and Umi fingerthrottle jet to be mounted. Do I risk backfiring if I don`t put the freeflow?

  10. #10
    Happily Self-Employed WFO's Avatar
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    Freeflow or not is a big dissusion here among guys on the forum. If you dont like the noise and like top end perf.- dont install it. The jetworks mod will give you a great low end punch. I dont run freeflow on my boat.

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