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Thread: gpr compression

  1. #1

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    Jun 2011
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    gpr compression

    i have been working on my gpr for awhile recently i have been trying to tune the carbs on it . i have made a couple of test runs and cheking the plugs between test. the other day i decided to run a compression test on the motor and i noticed that #1 cyl has a little compression loss on it. after i rebuilt the motor i did a compression test on it and the readings were #1-110, #2 112, #3 112 psi and that was before i had tried to run the motor. now after running the motor several times on the hose and a couple of times on the water i am getting readings at #1- 105, #2-111, #3-108. Does anyone out there know what might be going on with the motor. when i pulled it down to rebuild it i took the cyl.s in to a local shop to have them checked out and serviced. the shop said they were all ok.any help will be appreciated.


  2. #2
    Wake junky Gp1200R's Avatar
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    Your not seating those rings right..

  3. #3

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    Jun 2011
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    when you say i am not seating the rings right , what do you mean? am i not doing something right? when i run the engine i vary my speed and i did not run the engine wide open until i had run a full tank of fuel through it. please be more specific because i am a rookie when it comes to engine work.

  4. #4
    Wake junky Gp1200R's Avatar
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    10 gallons mixed 32:1 fire her up ride for 15 min let cool for 15 ride for thirty let cool for thirty... While always on and off throttle keep it 3/4 and down... Take that fuel to the buzzer then put in 10 gallons 40:1 ride to the buzzer and then she's good to go... The key is the good heat cycles... Take it to 3/4 throttle then get off let the rings seat...

  5. #5
    You have to Hone your cylinder walls first to soften it before you install the new rings or they wont seat right...so if you or the mach. shop didn't do it could be your prob.And have to make sure when the rings are installed that the groves on the rings are over the pins on the pistons,or air will pass by...

  6. #6

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    i had the machine shop hone the cylinders and when i installed the rings each piston has a positioning nipple built in for each ring. cant install the piston into the cylinder if the rings are not lined up with that positioning nipple. thanks for the info anyway.

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