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  1. #1

    65u blown engine help

    hey guys just looking for some advice on what i can do with my gp1200 as i took it out yesterday and it died whilst a friend and i were riding we swam it back to shore to find that the cylinder in number 3 has broken up in little pieces im not sure how or why this happened. what i would like to know is my options as im looking for the best way to do this weather there is engine conversions that will bolt in easily and perform well ie 4stroke engine or more powerful engines. or weather or not i should just rebuild and if i rebuild the engine what should i do with what to replace and so forth and what sort of money am i looking at to replace everything. i have also found a guy on ebay that does engine exchanges send in your old engine and what would be $900 being in australia and they send you a fully reconditioned ready to instal engine and would also have to pay postage. i can find a reconditioned engine here but the thing is its $2000. this is my first ski i have owned nor first engine i have had to rebuild or repair so my knowledge currently lacks. i would like to do this engine work once and do it properly so i can then have full trust in the ski to go on the longer some what sort of rides without the thought in the back of my head of i hope everything under this seat is running well and properly. any help would be greatly appreciated i will try to attach a pic of whats happened and the entrernals from when i pulled the head off when i got home.


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  4. #4
    Old Ski Insanity w/rpm500's Avatar
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    Aways my question on a two smoke.. how old was your fuel?? know your seasons are different than ours right now, but this happens often in the spring here..I cant stress enough GET THAT OLD FUEL OUT OF THERE if its been sitting more than a month or two with out stabilzers..that said...... you will have to pull that all the way down to inspect everything and to clean out all the metal thats circulated thru the motor.. you want to learn, tear it down. You wont know what your costs will be until such time .. then weigh a new engine or rebuilding what you have . ask questions here and on the two stroke forum.. typically the #3 goes before the others as the rear seems to run hottest on yami's...lots of yami guys in AU and in NZ that are closer and may be able to help with parts, look thru old school youll find a few..

  5. #5
    Moderator OsideBill's Avatar
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    I just ate the #3 in mine, mine was due to the rod bearing failing on the crank. I had over 400 hours on the crank and 300 hours on the top end. I have not split the cases yet, but I am guessing mine was due to rust on the crank wearing it down, I almost sank the ski two years ago, had water clear up to under the carbs and rode it 15 mins to get back to shore. I assuming that water may have gotten in my rear seal doing this, it may turn out that the bearing failed due to wear from age, won't be able to tell until I get it apart and check for rust. I was running 40:1 pre-mix and the #1 and #2 pistons and cylinders look great. The rear seal is one of the first things that comes to mind when these fail on #3, you will need to continue stripping the motor down to find everything that failed.

  6. #6
    Flying Scotsman's Avatar
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    Ouch that looks painfull.

  7. #7
    w/rpm500 the fuel was fresh that morning a full tank of 98 fuel and fresh oil i probably had used not even 5L's of fuel before this happened and im happy to learn i have come a long way by just playing with it myself and using this forum just need to weigh up which way to go with getting the engine sorted and back in and running stronger then before and to make sure this dosnt happen again.

    OsideBill thats unlucky i will be pulling mine out will probably start doing so today and remove the rest of the engine hopefully wont take to long the engine in mine i think is still from stock and from my gathering of information when the gauges last worked it was around the 260hour mark. so will try get it out and start stripping today to assess the damage and what to do.

    Flying Scotsman yeh sucks especially since its still pretty new to me but thats life this just means i now can do a heap of hull work and get it re sprayed and custom graphics replace allot of cables and new engine so i can have complete faith in the ski and it will look pretty afterwards ready to hit the water hopefully this summer thats coming up

  8. #8
    ill get some more photos today of it all and will post them up.

  9. #9
    B&V
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    first where do u live,year of ski,#3 seems to be the one that goes first,i'd replace all three pistons and resleeve the blown one,if the cases are good

  10. #10
    Flying Scotsman's Avatar
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    Post up some more pics when you get them,if the c/cases and cylinder's have no holes in them and there still stock bore you could have them bored.Mine are bored out to 86mm stock is 84mm.That bore is going to be pretty bad if its real bad you would have to install a new sleeve and then bore it.
    It might be time to go big bore and get some porting done.Just sayin !.

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