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Can I swap a 4-stroke in for my 787?

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Depends who you ask.

There isn't anything that will drop in. Not even the cleaner 2-strokes will fit without modifications. If you want to approach this you'll be looking at either making your own engine mounts, or using existing mounts and fiberglassing/building to hold them in place.

Also, I'm not sure if there's any motors that will easily fit front to back in your engine bay.

Let me know if you get anywhere with it though, I've been thinking about it too!
 
I was worried about how many of the engine systems are controlled by the MPEM and how different they would be between the two engines.

If it is too much of a hassle, I can put in a new/rebuilt 787 for under $1000. Maybe rebuild mine, if it isn't TOO damaged, but with the 1/2 cup of cast aluminum chunks I am finding between my piston and head...I doubt it will be salvageable.
 
can you swap a 4 stroke for a 787? in the XP? no. in the Challenger? maybe. you would be rewiring the entire boat, and fabricating mounts into the hull. THEN-you would hafta figure out if you can hook it to the 140 mm pump. unless you are willing to cut out the whole back of the boat and glass in a 155 mm pump mounting face. THEN you are gonna need to buy a whole running 4-stroke ski or boat for a donor. in other words-is it doable? no.
 
you would be rewiring the entire boat, and fabricating mounts into the hull. THEN-you would hafta figure out if you can hook it to the 140 mm pump. unless you are willing to cut out the whole back of the boat and glass in a 155 mm pump mounting face. THEN you are gonna need to buy a whole running 4-stroke ski or boat for a donor
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THAT is the kinda stuff I didn't want to get in to...

Thanks for the clear answer.:ack:
 
Yeah, anything is "possible", but I want to stick with what is "feasible"...

We just hit the peak of our season here this week...cool fronts coming through so you can ride without sweating, but still sunny and warm. I may not get it back into the water until next season, but it would be nice if I could get a couple more trips this year.

That being said, I don't want to reinvent the wheel.

I have never seen anything other than the 787 and was kinda hoping they were built so that they could be easily interchanged. Like doing a 250 I6 swap to 302 V8...
 
I have allways liked 4 strokes myself but I am not sure when it comes these seadoo 4 strokes that turn higher than 7000 rpms. This is some high rpms when compaired to cars or other small engines as these engines get age on them they seem to come apart. These high turning rpm engines do not seem to wear out from what I understand they just break [ come apart and stop runing]. Looking at your engine it looks as it was time for somthing like this to happen. I would like to know if there was a cause like oil or overheat or what ever could have prevented this from hapening. I believe it just may have been the end for this engine but I can allways be wrong. :cheers:
 
As far as electronics, you might be able to swap in a similarly powered carb'd 4-stroke without changing too much electronics. You could run the coils separately from the MPEM and then all you'd have to do wiring wise in the boat is work out a new kill switch mechanism...
You wouldn't be able to get the engine from BRP as they never made a 4-stroke carb'd motor afaik, so you'd have to go elsewhere for that.

As for changing out the pump, why would putting a bigger engine behind a small pump cause problems? I would think that having the small pump would mean you wouldn't be able to get the full performance out of the more powerful motor, but it should at least perform as well as the original motor did?
 
I asked when I bought the boat if the previous owner would be upset if I put a smallblock ford in there, and he said, "it's your boat, do what you want."

So if I was going to swap and had to do a LOT of fabrication, I would drop in a 5.0 with a modest 250hp and about as much torque.

But, I am not...and I won't...:reddevil:

It would be too low rpms anyway. And too much gas.
 
scooper77515 said:
I asked when I bought the boat if the previous owner would be upset if I put a smallblock ford in there, and he said, "it's your boat, do what you want."

So if I was going to swap and had to do a LOT of fabrication, I would drop in a 5.0 with a modest 250hp and about as much torque.

But, I am not...and I won't...:reddevil:

It would be too low rpms anyway. And too much gas.
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It seems that you have thought about it but I will ask any way's just in case someone else has not thought about it.Just think about it, To get the same kind of top end speed that the 2 cylinder rotax was geting, The ford would have to turn the kind of rpms that the rotax was turning. How long would you think that the ford would last at 7000 rpms. :cheers:
 
Like I said in my last post,

It would be too low rpms anyway. And too much gas.
Click to expand...

Now, with that kind of hp and torque, I could gear it up, but that just adds ANOTHER layer of difficulty to the job.

But just imagine, 300 hp and similar torque, spinning that jet pump to around 8000 rpm...:)

But I will do that when I get rich and have money (and time) to sink in frivolous endeavours such as that. For now, I need to get the wife and dog back out on the water, before they get too bit---er, irritable. :ack:
 
keep a eye open on ebay and craigs list it can not hurt to have a extra engine as it seems that me and you as well as others have been having problems with these old engines and if you have a spare you can rebuild your old one hopefully and it will only take a day to do a engine swap and when you blow your next engine you can take your time on the next purchase or rebuild and save a ton of money. :cheers:
 
scooper77515 said:
Like I said in my last post,



Now, with that kind of hp and torque, I could gear it up, but that just adds ANOTHER layer of difficulty to the job.

But just imagine, 300 hp and similar torque, spinning that jet pump to around 8000 rpm...:)

But I will do that when I get rich and have money (and time) to sink in frivolous endeavours such as that. For now, I need to get the wife and dog back out on the water, before they get too bit---er, irritable. :ack:
Click to expand...

Even though the rotax is only 110 hp I would think that the power band is unbelieveable for such a small engine. it could be = to some other 175 hp engines that do not deliver the same kind of torque. I am not sure and may be talkining out my a** so if anyone knows better please correct me if I am wrong.:cheers:
 
Good idea on having a spare. I have a 96 XP and 97 Challenger, both with 787 engine, so having a spare would minimize my time out of the water.

And, with these engines being so small and light, it isn't like keeping a spare 5.0 ford in the garage...
 
slap a hyabusa engine in there and call it a day, talk about some rpm's...............hit the limiter @ 17 grand.....that would be nice!:cheers:
 
hahaha ya man prob. spin that pump into oblivion......(hyabusa is the supposed fastest production streetbike by suzuki) for those who dont know. think its like a 1300 or 1400 cc 4 cylinder engine. i have seen people turbo charge em and get well up over 600 hp. man that would be fun!!!!:cheers:

o ya vilord, the smaller pump thing, from a stand up view the smaller pump actually hooks up better, example is my 440 with a 550 ish engine, the 440 pump, when properly blueprinted and bored will far excede the limits of the stock 550 pump but in this case i have no idea........
 
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