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  1. #1

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    GP 1200 cylinder honing job

    decided to take my GP 1200 cylinders to the only local place that works on jet skies,big mistake,they were standard size 84mm with some wear so i had them bored and honed to 84.50 and i got them back and noticed the clearances looked big,i checked the ring gap and that was at .024 checked with feeler gauge,i called the guy and his answer was ,you are not racing are you,that will be fine,i know the ring gap was measured by me properly but i only had a dial caliper to measure piston to cylinder clearance,that is around .018, i may not be accurate on that but the ring gap speaks for itself,these are WSW pistons and rings and the paper was in the box so he would know what to set it at,i know this will not work and the guy says it will,so i probably will end up having to send them off and get them bored .75 over,this sucks after paying for this job,i do not know if i will get anything back from him or not,does anyone know a good place to send cylinders to?


  2. #2
    Flying Scotsman's Avatar
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    Before geting them bored again you will need pistons.You always bore the cylinders to match the pistons.Buy a dial bore gauge and a mic and measure the pistons and cylinders and determine what the clearance is if its .018" thats huge what do wsm pistons call for im guessing .005".I would take them and show the who bored them and demand a refund.
    I have a good cylinder guy but I still check for piece of mind.
    Find someone you can trust and who is knows 2 smokes.

  3. #3
    Old Ski Insanity w/rpm500's Avatar
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    read my answers in red

    Quote Originally Posted by explorer6764 View Post
    decided to take my GP 1200 cylinders to the only local place that works on jet skies,big mistake,they were standard size 84mm with some wear so i had them bored and honed to 84.50 and i got them back and noticed the clearances looked big,i checked the ring gap and that was at .024 checked with feeler gauge
    .. the gap is larger than normal(.008-.016 o/e)..did you buy .050 thou over pistons?
    ,i called the guy and his answer was ,you are not racing are you, racing you would want this bigger than normal true, as rings swell ,..pistons also swell when hot, so more clearence is needed to race ..think hes going in the wrong direction for a rec ski
    that will be fine,i know the ring gap was measured by me properly but i only had a dial caliper to measure piston to cylinder clearance,that is around .018, should be between .0039 and. 0041 o/e measured at the skirt ,in line with the pin ..after market you may wish to check with the provider as different makes swell at different rates
    may not be accurate on that but the ring gap speaks for itself,these are WSW pistons and rings and the paper was in the box so he would know what to set it atpaper may have not been accurate, he should have measured anyways and then informed you of what needed to be done..did he ask if you were racing or of how you used your ski?
    ,i know this will not work and the guy says it will yes but not at peak efficency until good and hot,so i probably will end up having to send them off and get them bored .75 over,this sucks after paying for this job,i do not know if i will get anything back from him or not,does anyone know a good place to send cylinders to?
    once again what set did you buy? if .020 over (.50mm) you may only need to get it finish honed to get you in the ball park.. your rings may not be correct in the kit.. its been known to happen .have them checked also.. i had to file a set down to get the proper fit (mine were too large in the kit) get in touch with member OBXJEEP ,hes outer banks and may know a good shop local to you both..

  4. #4

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    I bought wsm .50mm over pistons with rings included ,paper included for settings reads .004-.0045 for piston clearance and .008-.016 for ring gap,i bought 3 new sets and all the rings are the same,the ring clearance is way to big at .024. piston measurement =84.36 from bottom of skirt up 10mm,and the cylinder bore clearance is 84.56mm,i borrowed the proper measuring tools so i could be more accurate.piston has way to much slop.

  5. #5
    Flying Scotsman's Avatar
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    .20mm is about .0075" thats a bit to much for wsm pistons I think.
    Never had wsm's though.I would have set them up at .005" if it was me.
    You might be able to run another brand of piston thats a few thousandths bigger and have the cylinders honed to fit.
    For example a Wiseco piston is bigger than a Pro X piston or oem pison.
    I set up Wiseco pistons at .006 -.007 ".
    oem or pro x .005"
    You might get away without boring just honing if you can find the right pistons.
    If he did go .008" then you didnt get what you paid for

  6. #6

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    i am going to take them back and argue my point on the bore issues,he also told me when i told him the specs for the ring gap and what i measured them at he told me he does not go by ring gap only piston to cylinder clearance when setting up cylinders,i am no expert but that does not sound right.

  7. #7

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    Cylinder Boring for 45.00 with FREE RETURN SHIPPING

    I Use ShortBlocksRus.com for Crankshafts, Shortblocks at my shop they also do cylinder boring for 45.00 each hole when you buy pistons or a Top end rebuild kit from them they have FREE RETURN SHIPPING back to you.

    I know that they have a good deal on Pistons and Top End rebuild kits.
    There building and adding parts to there website so you will have to call or email them.

    Here is the link for cylinder boring and all there info is at the Top right side of the page when you veiw it.
    http://www.shortblocks-r-us.com/prod...categoryId=243

    They do GREAT WORK and there fast and they will set up the End ring gap, chamfer the ports and do a final hone.

    Good luck

  8. #8
    Old Ski Insanity w/rpm500's Avatar
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    read red below!
    Quote Originally Posted by explorer6764 View Post
    i am going to take them back and argue my point on the bore issues,he also told me when i told him the specs for the ring gap and what i measured them at he told me he does not go by ring gap he is correct, ring gap is NOT a measurement check for correct bore.. (rings are checked for fit and filed if needed after the correct final hone clearance is reached.. if he set clearence at .008, he took to much off only piston to cylinder clearance when setting up cylinders,i am no expert but that does not sound right. its the total that counts..
    he may have 'inadvertantly' doubled the total when honeing,forgetting that total clearance is split to both sides..(he's not the first)
    half that .008 would be your ideal O/E .004..
    IMT he f'd up the math , so he should make good on his mistake...

  9. #9
    Moderator OsideBill's Avatar
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    Not on the subject but this does pertain.
    I have been told by the experts (groupK & Pro-Tec) I use this term loosely. That a 1200 65U motor must either have the exhaust manifold or a fixture plate mounted to the exhaust side during cylinder boring and honing to prevent distortion of the cylinder, once the exhaust is mounted final.

  10. #10

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    That would good to know,if that is the case then it is messed up more.

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