657 Confusion

[RocketFox650]

I always find it challenging to nail down exactly what each new ski I bring home is exactly because what's in them seems to always be a bit more fluid than what the PWC wikis and even SeaDoo service manuals say. Right now I'm working on a 95 title/94 hull SP, no real confusion, also have a backwards set of GSX, but then I've got 4 GTX. Supposedly a 94, 2 more 94, and a 95. My 94 has black flex boot mirrors which is different than every other one. The 2 grouped 94s have the 657x motor, which isn't listed in my 94 service manual so I had to download a 95, and then all my Google and wiki searching tell me that basically they changed the 657 timing and added twin carbs for the 95 model year to make the 657x. But then my single 94 which does not have the x on its cover label has twin carbs. Was there an in-between engine? Or end of the model year and they just put in what they had? I mean I've had that before... It's a running joke in my family how I end up with either preproduction or switch year vehicles, and everyone thought the swapped GSX thing was just dumb luck funny, but now I'm like 8 seadoo's in and nothing is quite what is supposed to be. Idk why these GTXs are so popular right now, but where I work, besides my 4 there's at least another 4 parked on the lake, plus all the ones that come and go, and since I'm getting paid to service them constantly, or in this case restore multiples, I'd like to know more about the motor.

 

[mikidymac]

Unless someone messed with it, Seadoo does not have pre-production skis or skis with the wrong engines in them.
The last two digits of the HIN is always the year and the engines are the same for every hull produced that year. Seadoo never sent out skis with the wrong engines for that model year.

The 657 and 657X have quite a few differences, carbs, pipes, intake manifolds, cranks, cases, cylinders, heads, but they were both dual carb.

Here is a good link to the 657 vs. 657X

 

[RocketFox650]

Unless someone messed with it, Seadoo does not have pre-production skis or skis with the wrong engines in them.
The last two digits of the HIN is always the year and the engines are the same for every hull produced that year. Seadoo never sent out skis with the wrong engines for that model year.

The 657 and 657X have quite a few differences, carbs, pipes, intake manifolds, cranks, cases, cylinders, heads, but they were both dual carb.

Here is a good link to the 657 vs. 657X

I haven't looked at them side by side really, I just noticed the EIN without an X, as well as twin carbs, and got confused. I can't remember which wiki it is, maybe PWC something or JETSKI history, but it gives an overview of each model year but it's really generalized so you don't get an exact description on certain models. Like if I Google one of my little skis specifically, nothing comes up about that model except at part of this one sites generalized summary of each year. Like it really gets into the XP changes, and some years it details SP* models, but it basically just says the SP existed and might have a picture of one of each model for the year. The GSX is another model they don't do enough detail on. Basically it exists in 96, and in 97½ there's a transition, and then details on the R.A.V.E. system or Limited versions after that. You take that, and mix it with the shop manual from SeaDoo, and it's about as clear as mud. Idk about your "no mid year" fact though mate. I've got 3 GSXs that don't fit that in some ways, and I've got an SP with a title that's a year off from it's HIN year according to this site. It's been awhile since I looked at that one specifically, but it's something like a 95 title but the HIN ends in 94 or 96. I know it's not the engine, but it's still not supposed to be like that I thought. And the factory paint is still intact on everything prior to me opening them, so I know none of them is swapped. Electrical/dash are what's different on the GSX hulls. Engines are all correct, but the I've got 3 different configurations of computers/gauges between 96/97. I hate this shop manual because the search function doesn't seem to work, but I found what I was looking at originally that got me searching GTX models to figure out what I was working on and found "introduced the 657x motor which featured twin carburators and a timing change increasing it's horsepower", so I assumed that 2+2=4 here and was wrong. I just spent 5 days restoring 2 657x hulls side by side in the water and opened the seat on a different GTX to show someone something, found 2 carbs, and thought something was up. The exploded carb view has a single carb with both MAG/PTO parts shown, and I missed that when I saw "all models except XP" and the XP exploded view is of both carbs. You can clearly see the sync bar and labels if you do more than look at the pictures. Generalization, trying to read laying in the footwells of a ski in the water at noon, another lesson learned. You seem like you're pretty knowledgeable on the history, so maybe you can answer another question- I've seen both yes and no, were rear ladders a factory option or part some years? I've got a parts catalog from SeaDoo that lists it but the hull I have from that year doesn't have one, and a hull that has one but I don't have a model specific supplement for that year to compare. The mirrors on that one also don't match any other ski I've seen, but look original, and I need replacements but don't have a part number.

 

[mikidymac]

I would love to help you get to the bottom of your models as I find it interesting.

The year on the title means nothing and is just what the Department of Motor Vehicles listed. The actual model year of any ski is the last 2 digits of the HIN. Don't worry about the engine tag numbers either.

Back to your 3 GSX's, there is only two options if you have a 787 engine. 1996 will be blueish purple and white with a 787 and the older electrical box. 1997 will be red and white with the newer integrated MPEM, that is it, there isn no 3rd half model or anything else.
The only 1997-1/2 is the silver and red (Gray Ghost) that has the first 951 engine (white engine).

There is no single carb 657, there was only the 657 and the 657X and both are dual carb.

If you can post pictures of your skis we can determine once and for all what they are.

The carb diagram you posted above isn't showing if you have a dual or single carb ski, it is just showing the parts breakdown and is noted that the PTO carb has a blockoff plate instead of the fuel pump.

There were no factory installed boarding steps. You could buy them as a seadoo accessory and have the dealer install them or buy them yourself from Aquastep or Kona and install yourself.