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  1. #1

    98 GTX 800 project, questions

    Hello all, I'm Bob from MI and a newbie to the site and PWC's. Any suggestions for mods would be appreciated. I have a 98 GTX 800, needs a new top end and plan on doing the following mods.

    Cylinders are stock and removed, but I need to pull the motor. I plan doing some porting to the cylinders, boring them .020-.040 over and using some wiseco pistons. How do you disconnect the pump or output shaft from the motor?

    The cylinder head will be milled and re-chambered as necessary to run on 93 octane.

    The 40mm carbs seem small for a motor of this size. I'm looking for a set of 45mm carbs if you know of anyone who has some. My question is the rotary cover looks like it would be pretty thin after modding for carbs this size. Do they make a different cover or did they just mod the stock ones?

    I also need help and suggestions on what to do with the imprellar and intake grate?


  2. #2
    elmatta's Avatar
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    If the 800 motor is similar to the 951, then try removing:

    1st hose clamp using that special hose tool that removes those types of clamps
    2nd (You may be able to pull back the boot with just the 2nd clamp off) and 3rd hose clamps using a screwdriver.

    If you pull back the rubber boot, it should expose some C clip looking washer that disconnects the PTO flywheel with the drive shaft (I think). If the motor mounts are off, you should be able to slide the engine to the left a little bit to remove it from the drive shaft and boot setup. It will have a lot of grease so it might take a good yank to the side. I wasn't able to remove my engine with these steps, so I just removed the nozzle/impeller housing and yanked the drive shaft out. Should come out pretty smoothly
    Click image for larger version. 

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  3. #3
    Having Fun jp1300r's Avatar
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    You have a picture of the ski and engine. Pretty sure the 1998 GTX had a 951 that year unless its a GTX-RFI.

  4. #4
    elmatta's Avatar
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    Any updates?

  5. #5

    update

    The cylinders cleaned up nicely going .020 over and I ended up using Pro-x pistons. I can get away with a tighter cylinder clearance than using wiseco's and avoid the piston slap noise you can get with running a forged piston with a looser tolerance. I have not weighed the pistons yet but I usually prefer wiseco due to their lighter weight. I'm going to see if I can shave a few grams here and there. I've begun the process of porting the cylinders, some definite improvements will be had with porting. I'll post some pictures when finished if anyone is interested.

    I purchased a Rossier pipe of e-bay for $150 and I'm still looking for the 44mm carbs, the Mikuni super bn's can I make work. Also got a manual and hope to get at pulling the motor this weekend. After the motor is pulled I'll need to split the cases for the case porting. The carbs are becoming the critical point because if I go with bigger carbs, I need additional case work to accomodate them. More to come...

  6. #6

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    looking for updates on this

  7. #7
    Slow on the progress but with snow on the ground here, no need to rush. The motor has been pulled and the cases were split. The two front main bearings lost the ball keeper so its needs some new mains and seals. I plan on doing some case porting while I'm in there as well. I was contemplating adding a 4mm stroke to the crankshaft since the bearings are bad, but that could easily add $1000 to the project I don't want to spend. I likely will just replace the bearings or just buy a new complete crank and be done with it. I also will likely lighten the PTO flywheel, and replace the counterbalancer bearings. For the carbs, the bigger ones seem pricey so I will likely just bore them to a true 40mm with different butterflys.

  8. #8
    Electronics Guru Alpheus's Avatar
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    Are you sure that its an 800 engine? My 98 GTX had a silver 951.

    Also dont forget to shave your RAVE valves with that over bore...

  9. #9
    Finally getting started on the project. Here is a picture of the porting. Click image for larger version. 

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  10. #10
    transfer portClick image for larger version. 

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