Just purchased 2000 Seadoo GTX RFI 787 for $350-need help!

[Bonmotwang]

Nah, I've ALWAYS been into cars, bikes, motors, anything tech related! Haha!
Btw: when is it necessary to ground the spark plug wires? I guess when cranking and checking compression?
I know it has to do with them shorting out and messing up the PCM, right?

It won't short out anything because the rubber boots on them. But it will generate high voltage when you crank the engine by pressing the start button, which may cause arc to a ground piece such as the engine block, or damage the MPEM if the arc finds its shorts path.

But I have never grounded the plugs just laying it at the bottom of the hull away from any wires.
Probably I got lucky. I should've follow the right ways because the ground post are there for a valid reason :-D


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[racerxxx]

Most importantly, so an arc doesn't ignite fuel vapor. It happened to a member a few years ago. The guy got it good.

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[Bonmotwang]

Most importantly, so an arc doesn't ignite fuel vapor. It happened to a member a few years ago. The guy got it good.

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Yep. Forgot to tell him why arc matters.


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[96spxpos]

yes,
first things first!
I was excited like you were, had a battery, drained it, and didn't want to wait for it to charge, so I jumped it off my Mitsubishi eclipse at the time, fried the MPEM.
That'll run you just as much as you paid for the ski and trailer, so, RESIST THE URGE!!!!
Second, I personally would not try to turn the motor or run a compression test or ANYTHING without putting some fogging oil or some API-TC oil down the "jugulars" first...

This will keep scoring and scratching to a minimum.
Ive seen a youtube vid where a cylinder was literally frozen, the guy wound up using a mallet and oil, freed the piston, cleaned it all up, lapped the valves, etc, and it ran like a top. so it appears "lubrication" makes all the difference in the world.

 

[96spxpos]

well I also heard the one about the "Seasoned, well versed Marine Mechanic" who poured straight gasoline down the carb throats, no flame arrestors, etc, and burnt half his face off..
DONT DO THAT!

 

[GTX RFI]

I got my GTX RFI running this year after it sat for 6 years, Things it need was new fuel injectors, fuel pump and oil tank which i havn't replaced yet it has a slow leak. Jammin777 and Griz were a great help on. While it is sitting make sure you use this time to keep fogging the cylinders to allow the oil to seep down and also the fuel rod has a quick connect remove the fuel line to discharged the old gas if there is any left in there have a container ready to put the fuel line in.

 

[Jp6940]

Preliminary numbers don't look good.
25psi on one cylinder and 145psi on the other.....
What does that mean? I opened the throttle and cranked about 10-12 times....
That kinda sucks.

 

[Mekanix]

Just means it might be stuck rings or needs a top end.

WSM top end kits are one option and are around 250 $

 

[Bonmotwang]

Preliminary numbers don't look good.
25psi on one cylinder and 145psi on the other.....
What does that mean? I opened the throttle and cranked about 10-12 times....
That kinda sucks.

No worries they rock, not suck .
The professionals here will help you out on the top end rebuilt. I had zero knowledge about boat and engines. Sportster and Waterlover literally guided me through every single step needs to be done and needs to be known and needs to be aware. and on hourly basis!!!. You will feel lucky that you are in this community. Some fixes and some fun!

Your ski would be somebody's dream project to have, very clean, very good starting point to learn 2 strokes.

 

[Jp6940]

Yeah, 25psi on " front" cylinder and 145psi on the "rear".
I put new plugs in it and decided to fire it up. It started right up and ran for about 10 seconds very roughly and stalled. It didn't sound too hot. So where do I go from this point? I took video with my phone of the initial start up and running. Sounds pretty rough though.
Would it be the crank or top end? Kinda bummed at this point.

 

[Spimothy Leary]

no point in being bummed, its still an absolute bargain at that starting price.

 

[Bonmotwang]

Yeah, 25psi on " front" cylinder and 145psi on the "rear".
I put new plugs in it and decided to fire it up. It started right up and ran for about 10 seconds very roughly and stalled. It didn't sound too hot. So where do I go from this point? I took video with my phone of the initial start up and running. Sounds pretty rough though.
Would it be the crank or top end? Kinda bummed at this point.

Hey. Better wait there for some suggestions. Take the plugs out and turn the flywheel by hand if you want to play with it a little on your own. And listen to the sound from the engine.


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[96spxpos]

JP,
DID you lube the cylinders at all before you tried cranking it? just curious man...

 

[Jp6940]

Eh, not really. I sprayed one squirt of PB blaster in each cylinder. Didn't think one squirt would hurt any. I know carb fluid wouldn't be a good idea because it would wash out the cylinders. I mean it wouldn't run at all If I had stuck rings/piston, right?
I started it for about 10 sec then it just kinda died out. Surprised it even started with 6 year old gas in it!!?
The weird thing is: it shouldn't have even started with 25lbs in one cylinder and 145lbs in the other right?
Damn, you guys have super quick responses!! I'm sorry if I am posting a lot of questions. Kinda bummed, excited, confused. On top of that, I told my wife it didn't run and she FLIPPED OUT!!!!!!
Hahaha, I tried to tell her that $350 was a good deal but she didn't wanna hear that shi!
So at this point, would you guys guess it is top or bottom end? Why did this occur with 90hrs of time on the ticker?

 

[scrisp]

Eh, not really. I sprayed one squirt of PB blaster in each cylinder. Didn't think one squirt would hurt any. I know carb fluid wouldn't be a good idea because it would wash out the cylinders. I mean it wouldn't run at all If I had stuck rings/piston, right?
I started it for about 10 sec then it just kinda died out. Surprised it even started with 6 year old gas in it!!?
The weird thing is: it shouldn't have even started with 25lbs in one cylinder and 145lbs in the other right?
Damn, you guys have super quick responses!! I'm sorry if I am posting a lot of questions. Kinda bummed, excited, confused. On top of that, I told my wife it didn't run and she FLIPPED OUT!!!!!!
Hahaha, I tried to tell her that $350 was a good deal but she didn't wanna hear that shi!
So at this point, would you guys guess it is top or bottom end? Why did this occur with 90hrs of time on the ticker?

Congrats on your Doo, they are so much fun, once you get them running good.

One squirt of PB BLaster won't hurt anything, I overdo it with fogging oil every fall, and the only issue is with smoke. lol

Does this model have the grey tempo fuel lines? If so, they breakdown over time and clog the fuel system, so they should be replaced. If the gas is that old, I would not try to start it until you remove/replace it. You want to start with everything fresh, they way you can rule out the easy stuff first, if it doesn't run right. Even after you put new fuel in, it will run rough until the lines get the new fuel to the engine.

While you are waiting to do that, I'd check and clean every electrical connection. I went through an ordeal when i replaced the engine in my XP this summer, and it ended up being a bad battery, followed by corroded/lose electrical connectors. I wish I would have checked the easy stuff first. lol

And if worst comes to worst, and you have to replace the entire engine, you still got a steal on it. I bought my '96 XP from girl who couldn't get it to run. She just wanted it gone, and for $500 with a trailer and bin of extra parts, I was more than willing to make it happen. lol It ran great, but I dropped a screw down the intake and hosed the engine. I bought a rebuilt for $800, and had an ball with it over the summer. :driving:

 

[Bonmotwang]

On top of that, I told my wife it didn't run and she FLIPPED OUT!!!!!!
Hahaha, I tried to tell her that $350 was a good deal but she didn't wanna hear that shi!

If you still love her, that is way too much information and detail for her. LoL

 

[Davidgsx]

I tell my wife every single project I get is $100, and I always have 2 or 3 going!! You would think at some point she would call bullshit on the mere fact that it's always " 100 bucks honey"


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[Bonmotwang]

I tell my wife every single I get is $100, and I always have 2 or 3 going!! You would think at some point she would call bullshit on the mere fact that it's always " 100 bucks honey"


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When i did my rebuild, I told her: honey, I just cleaned it up.

 

[Davidgsx]

So it seems I'm not the only one who finds it beneficial to massage the project numbers!


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[jhjesse]

Squirt some fogging oil or pb blaster in the cylinder (generous amount) and let it soak overnight then try the compression test again. Could just be a stuck piston ring after sitting for six years. It's worth a try anyway. The worst that could happen is a new top end anyway. JMHO

 

[Jp6940]

Yeah but I don't understand how I piston ring could get stuck with the engine running??? Doesn't the rods have to go up and down?? If a piston ring is stuck then the engine wouldn't turn over correct? I mean it ran for about 10 seconds then just kind of stalled out.... But didn't sound very good almost like a clanking kind of noise
So here it sits until I learn more:

 

[Bonmotwang]

Yeah but I don't understand how I piston ring could get stuck with the engine running??? Doesn't the rods have to go up and down?? If a piston ring is stuck then the engine wouldn't turn over correct? I mean it ran for about 10 seconds then just kind of stalled out.... But didn't sound very good almost like a clanking kind of noise

Stuck means the ring stuck in the piston groove.
Normally it slides in and out small amount and with its tension, rings are pushing itself against the cylinder wall, so that it seals well, so that you get high compression.
But if the ring stuck in the piston groove it is "dead" and not adjusting / pushing itself to the cylinder wall. When the piston moves up and down, it won't seal well.

Edit: so stuck doesn't mean it is broken and stuck there not moving. It still moves with the piston but dead.

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[soccerdad]

No, a stuck ring is the ring is the ring stuck in the ring grooves, not to the cylinder. The rings push out like springs. If they are gummed up, corroded, etc, they may be frozen..... well it looks like Bonmotwang beat me to it. Yep, just what he said!

 

[jhjesse]

That is a nice looking cover. You really scored on this.

 

[Jp6940]

I got ya now!!! I was thinking stuck as in it won't move up and down!!
I thought the cover came with it when you buy them new?

Anyway, I pulled the plugs and tried to shine a bright led light down the spark plug home while I used a small mirror to look in there-can't see much I put a pencil down in the cylinder and rotated the crank while I held the pencil-I felt a little bit of looseness on the piston while it was rotating-not sure what that means though. Maybe the rings are shot and it's making the piston "wiggle" side to side?

I did spray some more PB blaster down in there. I'll let it sit over night then try to crank it without the plugs in. Don't think that will help because it was making a noise I'm not used to while running those 10 seconds. Cracked open the gas filler knob and the gas smells pretty strong-not like old gas/petroleum smell like I've smelled before.
So I guess next would be to pull the head off? Any hints/tips other than loosen from outside in alternating the screws back and forth?

Okay!!! Update!!!!!
I pulled the top two covers and this is what I found!!

And this:


AND this:


So now I know why the cylinder only had 25psi pressure! From here......what do I do? I ran my fingernail around the cylinder and I found one tiny scratch with my fingernail. My friend said I could get a new piston, and larger rings? Or do I just buy 2 new heads? I didn't realize the heads were separate? So I can just buy one???
The small pieces of metal appear to be pieces of the rings....? I am a little afraid that more pieces fell down into the small holes down into the block....that would kinda suck huh? So now I am getting somewhere!