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  1. #1

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    97 GP 12 long post but need help bad!!!

    I think I screwed up. I am new 1yr into the sport. I had the illusion that a my GP would run with GPRs. So I tried to build my GP for speed. I bought a SBT motor (worst move ever, effn JUNK!). I ran it for about 4 hours when the incorrectly installed rear main seal fell out. SO heres what I did. I bought a new set of OEM cases as SBTs were poorly repaired. I used their crank, pistons, and cylinder. I bought a solas J 14/20 prop, RIVA spark arrestors, Billet trim tabs, R&D ride plate, primer kit no chokes. Well now my cylinder has a score in it, and par for SBT the other two sleeves are not aligned very well. So i picked up a head with 39.5cc domes and am planning to buy a ported cylinder. What cylinder/piston setup would give me a quick and reliable river boat?


  2. #2
    Hydrotoys's Avatar
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    Welcome Slow!
    There are some good 65U folks on here. Give it a few days and see what kind of results you get.

    Sounds like you went down the SBT road. Were you out of their warranty period too?

  3. #3

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    No but I choose to void it by replacing the seals and cases myself. I figured why ship it, deal with them, only to get more crap back.

  4. #4
    spud's Avatar
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    The old GP's will not hang with the GPR's but they are quick and fun. Sorry you went the route of SBT for an engine. When you get into that game the only thing you can do is make them replace the engine per the warranty. The core you sent them was probably better than the rebuilt engine you got back.

    Pro - Tec does a nice job of aligning the sleeves and matching the ports. They can also check the cylinder and make sure the bores are correct. Also have them check to see if the cylinder has been decked. Pro - X makes good pistons. Pro - Tec uses connecting rod to wrist pin bearings that do not require thrust washers. Take the choke plates out of the carburetors and add a primer kit. I put Riva cone arrestors on mine. If you make the changes I listed you will need to richen your low speed jets one full size (105 Ign, 100 Mid, to a 102.5 PTO I'm pretty sure that is where I put them) accross the board the high speed jets are fine. The ski will run all day WOT but will seize at partial throttle with stock jetting

    I have run R&D and Pro Tec intake grates the one that worked best for my ski was the Pro Tec grate with the wings cut off.

    Get the 1998, 1999 reduction nozzle 5°, remove the siphon tube and fill with epoxy also blend out the visibility spout and fill with epoxy fill and sand until it is smooth. Add duckbills and a Rule bilge pump. I put the automatic bilge pump in mine. I chose the SOLAS XO impeller, but I hear the J is a little better on top end. For the head I would personally have Group K mill the stock head. I am running stock compression now. I put the Riva sponsons on my ski. They eliminated the out of control feel the stock sponsons had while running WOT in rough water. My stock sponsons would catch an edge and feel out of control. I put the 1100 Raider exhaust stinger on my ski and I set up the Fercho Jetworks valve on it.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

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  5. #5
    Pistonwash's Avatar
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    Slow..you need to get that cylinder to a proper machinist and have him re-bore and hone those sleeves correctly. Give him your pistons and rings so he can get proper ring/piston clearances. Have him bolt on the exhaust manifold to make sure the cylinders are'nt bored "out of round" this time around.

    Send your crank off to (Crankworks) and have them true and weld the crank. They know exactly what to do and how to do it.

    I think you can bore .50 over and be good to go. Use a Pro-X piston kit, they work great..don't use the el cheapo piston kits. You get what you pay for. Get the engine in shape first, then work on your handling when that is complete. We have quite a few resources to show you how to re-build and set-up your 65u to run fast and be reliable.

    If you plan on assembing the engine yourself when the machine work is done, then get a 65u manual and a GOOD torque wrench. this will be an invaluable tool when re-building. Torque to specs and use the correct Loc-tite and engine sealants. I use Yamabond or 1211 for the cases, I will use green Loc-tite around the crank journals to keep them from vibrating. Make sure crank pins are aligned when re-installing crank into cases.

    If you are uncomfortable re-assembling your engine, there are a number of qualified and capable tech/tuners on this board that you can send your engine to. If you need a list or numbers, we can provide that to you.

    The most important consideration you have now, is to do it right this time and the ski will last and be fast.

    Have any questions, just ask.

  6. #6
    spud's Avatar
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    I guess I must have deleted the other pictures. Here is one of the stinger labelled
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  7. #7
    spud's Avatar
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    Jet Works under the seat
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  8. #8

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    The crank I have is "trued and welded" but by SBT. And the jugs I have are junk as I see them. The mag side has a huge chunk missing from the port and the other two are not lined up right. So as it sits right now I was planning to run a ported cylinder, from who? I dont know, my SBT crank, through my chokeless carbs.

  9. #9

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    BTW my junk jugs are already 1.00 over

  10. #10
    Hydrotoys's Avatar
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    But, aren't your jugs iron lined? If so, just get some some new LA Sleeve liners and have a REPUTABLE local shop do the swap.

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