1. A

    1996 Seadoo XP cuts off at full throttle after 1 second

    For the last year I've been rebuilding my dads 1996 Seadoo xp that sat for about 15 years, I pulled the 787 motor out of a 97 gtx, I cleaned the fuel tank, and oil tank replaced the MPEM, got new fuel lines, new oil lines, new fuel selector switch and filter, new spark plugs, new impeller, and...
  2. H

    Trying to figure out the max amps the rectifier puts out

    Hey guys and gals, recently purchased a 1998 challenger 1800 with twin rotax 787 engines. I’m fairly pleased with the boat and have had it out a couple of times now. I want to be able to use the boat for longer day trips without the sound system killing the battery and leaving me stranded on the...
  3. James_bond12

    Removing remaining head bolt pieces

    TL/DR: Two head bolts broke while removing. I can’t get them out (even with threading the top and using nuts) What would you recommend doing. About a year ago I starting fixing this 96 xp (787). I did everything I needed to get it running (new plugs, rebuilt carbs, replaced fuel lines, etc)...
  4. Challenger1800!

    MPEM needed Challenger Speedster 1998-1999

    Looking for a used mpem for 98-99 challenger or speedster with key. If anyone has had their MPEM replaced. I'd be interested in dissecting the old mpem board to learn how to repair it even if key is missing. The old owner of mine DESTROYED the one they fried due to jumping. Part # 204470155
  5. 1

    Please help me figure out what year and model my seadoo is

    I’ve been trying to figure out what seadoo this is for a while. Whenever I put the HIN in a decoder, it comes back invalid. Note this is the correct hin on the seadoo with no typos. Here is the hin: ZZN05638R949 It also has a rotax 787 Thank you, Allan
  6. A

    1998 Seadoo Speedster Port Side engine no spark.

    Let me get all the good info out of the way. I just purchased this boat and was instantly informed the Port side engine has no spark and the previous owner had already replaced the MPEM module and supposedly had both motors pulled and new magnetos installed. Decided to bring it home and...
  7. Doug Overkill

    787 Counterbalance shaft oil & seal question

    Working on my 1997 Seadoo Challenger 1800 with twin 787's. Some may have seen my other recent post about 2-stroke oil leaking past the crankshaft seal and hydro-locking the Mag cylinder on the port motor. After a bunch of overthinking it, I decided to tear apart a good working motor to solve...
  8. m33ndo

    1998 Seadoo Challenger Rave Valve + Carbs + Engine Questions

    Howdy All! I just bought a 98 Seadoo Challenger. The port side engine doesn't start up. I figure with a little bit of elbow grease and some new parts, I can get it back up and running. Worst case, I'd rebuild the engine , but really hoping to avoid that if possible. The first thing I noticed...
  9. F

    97 Xp 787 Runs but won't start

    1997 Seadoo XP 800 carbureted I just rebuilt the top end of my 787, 120 psi on both cylinders. It has spark with fresh spark plugs It turns over when I click start but won't fire up, (with or without choke or throttle) When I pour fuel in the intake through the carbs and click start, it...
  10. Logan.mchose

    1996 seadoo xp no spark no gauges

    I rebuild an xp, whole engine, most components. Lost the OEM MPEM in the mail so I got an aftermarket one. Seems to work, it beeps twice when key is on and will turn over fine. I have no spark or gauges though. Replaced coil, starter solenoid, stator, and flywheel, I have no idea. Maybe the...
  11. Happy_til_it_Hurts

    Hydro locked via garden hose, please advise (04 GTI Le RFI 787)

    After nearly a year I finally got my weekday ski up and running yesterday,  someone in this household came behind me at 8pm and hydrolocked the engine, despite me saying "that noise ain't the battery draining" >Plugs are pulled, wires to grounding plate, no turn with start just clunkish clock...
  12. mejim707


    96 Challenger with Rotax 787: I'm looking for suggestions and recommendations on what you GURUs have done with your own boats or skis to really dial them in. My current adjustments: FUEL: 87 Octane from the Gas Station (Not marine fuel) OIL: XPS 2 Stroke Synthetic Oil Gallon 779127 -...
  13. M

    1997 GTX 787 only hitting 5k rpm

    Hi guys, lookin for some pointers (already read every post on the internet including here and followed the advice but no fix yet) Got a 97 gtx that stopped running right and was left in bits for a few years. Rebuilt it recently but cant get it beyond 5k on the water. Can rev the danglies off it...
  14. S

    How to install oil seal in 787 magneto housing without $150 in specialty tools?

    Hello all, I have a 1996 GTX. It has moisture damage inside ignition housing and i am replacing just about all contained parts. My question: Is it possible/very difficult to remove old and install new oil seal in the magneto housing without the pusher and handle specified in the shop...
  15. H

    787 Impeller Shaft: WSM washer not fitting

    Hey all, Just rebuilding my pumps on my 98 speedster with twin 787's but I am about to torque it all down but before I do, I wanted to ask if anyone had any issues using the WSM rebuild kits for the pump, more specifically, the thrust washer not fitting in the center bore (when putting it in...
  16. H

    787 ugly under head surprise 98 speedster

    In my 1998 speedster the boat engine was not starting right, randomly shutting off, didn’t run right, stall at low rpm, had a vibration/rattling noise coming from back ,etc. I decided to do a full tuneup to see whats up (carbs, new filters, oil, head gaskets, peek inside to check pistons, plugs...
  17. A

    97 GTX wont run in water past 3400rpm. bogs down

    I recently bought a 97 gtx from a guy that had let it sit for years. I replaced the old gray fuel lines right off the bat. Rebuilt the carbs. New battery. New spark plugs and wires (cut 1/4" off before installing boots) . Cleaned the rave valves. Drained the fuel tank. Replaced the oil injection...
  18. Gdgough12

    Recharge jet. 1997 xp carb.

    What’s a good substitute for this part. I lost my recharge jet and they don’t sell them anymore. What’s a good substitute for it. Thanks!?!? I DONT WANT TO REJET THE CARB. I just need this one part. The card has already been rebuilt.
  19. H

    1998 Speedster Twin 787's - Which battery?

    Hi guys, I searched and I saw a few suggestions here, but I want to be absolutely sure I get the right battery here fro my 1998 Seadoo Speedster with twin 787's (partially to eliminate this as being a possibility of being the cause of one of my issue where one engine shuts off randomly, plus...
  20. P

    1997 GSX electrical problems

    Hi everyone. Recently started having issues with my 1997 GSX. I was out on the lake and my rectifier went bad. I replaced the rectifier with an OEM used one and it ran great right after install, but coming back to it the next day, I found the battery was dead. I put it on the battery charger...