I have a complete 717 (crank is bad) and a complete 787 (in a 1996 xp, needs pistons). I know they are the same bore, are they interchangeable? Keep in mind I have both complete engines so I can swap out whatever parts need to move from one to the other... I'd like to go in the water this weekend!!
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787 cylinders on a 717 lower end???
- Thread starter dppb
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Then your 1996 XP does not have a 787. All 787's have rave valves.
580, 650 & 720 never had rave valves. All 787, 947 & 951's have rave valves.
Also the 720 and 787 use different part numbers for the pistons so they are not interchangeable. They might have the same bore but my guess it the piston pin height is different.
580, 650 & 720 never had rave valves. All 787, 947 & 951's have rave valves.
Also the 720 and 787 use different part numbers for the pistons so they are not interchangeable. They might have the same bore but my guess it the piston pin height is different.
It's written type 787 on the block, no raves, 82mm bore, that's all I can say for sure....
Actually you are the first on to say it won't fit, and not a guess. What is the difference?
Not to be a jerk but are you sure what a rave valve is. On the exhaust side there is a big black plastic cap with a red circle in the middle. THe 787 will sit on about a 45 degree angle on it's side whereas a 720 will be straight up and down in the hull.
I understand asking, I am sure of the difference, I (succesfully) rebuilt both 787's in my 1997 challenger 2 years ago, including having the raves ground to clear oversized pistons. My "787" definitely dosent have raves. Here's the interesting part: block has the tag with "type 787" on it, cylinders have casting number "6923230" on them... the same as my 717....
Bought this ski from a guy that had it for 10 years (not mechanically inclined) he lost power, took it to garage, they diagnosed low compression. All they did was take put the plugs.
So options are.... wrong tag on block, or its already a 717 787 frankenmotor
Bought this ski from a guy that had it for 10 years (not mechanically inclined) he lost power, took it to garage, they diagnosed low compression. All they did was take put the plugs.
So options are.... wrong tag on block, or its already a 717 787 frankenmotor
I don't pretend to know what the difference is but I just checked and WSM, Pro-X and seadoo all list a different part number for the 720 and 787's. There would be no reason for them to have two different numbers for the same piston so the best I can say is I don't know.
[MENTION=7175]matt[/MENTION]Braley here would though.
[MENTION=7175]matt[/MENTION]Braley here would though.
The type code is not always the correct code for the engine displacement. The easy answer is if it has raves and sits at 45 degrees in the hull it is a 787. If it sits straight up and has no raves it is a 720 end of story.
One picture of the engine and I can tell you what it is.
One picture of the engine and I can tell you what it is.
No, I would say the 787 on the tag doesn't necessarily make it a 787. Seadoo uses some weird family names. Like a 1997 XP is actually a 5662.
720
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787View attachment 35516
720
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787View attachment 35516
critracer
Active Member
He might have this set up in his 96 but then it would have different motor mounts. Heck I don't know but the links are still a good read.
http://www.seadooforum.com/showthread.php?67306-785cc-hx-Motor-let-go
http://www.seadooforum.com/showthread.php?56355-Vintage-Performance-Rossier-Catalog-5
http://www.seadooforum.com/showthread.php?67306-785cc-hx-Motor-let-go
http://www.seadooforum.com/showthread.php?56355-Vintage-Performance-Rossier-Catalog-5
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Spimothy Leary
Well-Known Member
I have both 787 and 717 cyl's in my garage from two recent part out's, I guess if this is still up for discussion I could compare the two.
So it appears that you have a 797 bottom end and that mean's a longer stroke than the 717.
It also appears that you have 717 cylinders that have been possibly re sleeved with 787 sleeves or something else that was custom.
You might be able to bolt on the 717 cylinders but the piston deck height might be different between the two engines since we know so little about what your 787 is made of.
I'd say disassemble the 787 and figure out what you have in there in the first place. Take measurements. Compare, Bore, deck height, or any other parts of the piston that appear different.
It also appears that you have 717 cylinders that have been possibly re sleeved with 787 sleeves or something else that was custom.
You might be able to bolt on the 717 cylinders but the piston deck height might be different between the two engines since we know so little about what your 787 is made of.
I'd say disassemble the 787 and figure out what you have in there in the first place. Take measurements. Compare, Bore, deck height, or any other parts of the piston that appear different.
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