Switching Engines

[SEA-MONSTER]

Hi, I currently have a 1994 SeaDoo Explorer with a 657 motor in it, I recently purchased a 96 GTI with a 720 motor in it, I want to install the 720 into my Explorer, (these are both non DESS boats) beside from swaping MPEM's and a prop is there anything else I need to know?
Thank you,
John

PS, I plan on rebuilding the 720 and rebuld the carb (single) before installation, both cylinders have 110psi, not bad but, might as well start fresh!

Any input would be appreciated

 

[seadooya]

should be plug n play, sport. Probsbly need to make some longer leads and such, but not rocket science....good luck ,and post up some pix. We like pix.

 

[SEA-MONSTER]

I am going to just switch the moduals not the whole box, and yes I will post some pics!
Thanks,
JB

 

[jhjesse]

Why???? The electronics are the same. Should be just a matter of plug and play.
What you should do is switch out the flywheel mag. I believe the 657 is a 5 wire dual coil stator and the 717 is a 4 wire single coil stator. Everything else will convert over. just plug and play.
People who race skis use the dual coil setup for better durability and performance.
If you use the 657 exhaust you might have to reroute some water lines, but no big deal.

 

[seadooya]

i hear ya, Jesse, but keeping it simple, its best, and with him having the componants, to just make it a simple swap.

You know how it can be, pop'n a flywheel, drop'n a woodruff key,...

 

[jhjesse]

i hear ya, Jesse, but keeping it simple, its best, and with him having the componants, to just make it a simple swap.

You know how it can be, pop'n a flywheel, drop'n a woodruff key,...

Yeah seadooya you are right better to keep it simple...so why not just use the existing 4 wire setup and make it a true plug-n-play? got it buddy!!

When you go out on the lake are the fish so fearful of you that the jump out of the water?? LOL

 

[Minnetonka4me]

Yeah seadooya you are right better to keep it simple...so why not just use the existing 4 wire setup and make it a true plug-n-play? got it buddy!!

When you go out on the lake are the fish so fearful of you that the jump out of the water?? LOL

Yeah but unfortunately they are flying carp...LOL

 

[SEA-MONSTER]

Since I will have both engines out, I will switch the flywheels & stator, and I do have the pipe for the 720 (thanx Jhjesse) then im going to put the 650 in the GTI and try to sell it!! I wont get much for it but hey its something!

 

[seadooya]

they must fear me, i dont get even a da$# nibble....what else can it be?

 

[jhjesse]

they must fear me, i dont get even a da$# nibble....what else can it be?

OK...so the fish fearing you is maybe not such a good thing, but women wanting you has to have it's advantages!!

Sea-monster keep us posted on your progress.

 

[Hulluhaminalainen]

Hi,

About the engine switching:
Does anybody know what modifications must be done to install a 787cc 110hp engine to explorer???
Is the engine mount the same?
Ofcourse it needs the carbs, pipe and impeller.
What about the electronics are those the same as the ones in the 657 and 717 engine.
Propulsion system is the same I think because it has same 139,5mm impeller in 657, 717 and 787 models for example SPX -97 etc.
I´m planning to get an Explorer -93 or -94 I´m not sure which on is it, maybe an -94. I think the engine is the 657...
Engine has flooded in the late 90´s and it was then disassembled and greased.
Engine has been in wooden box partly reconstructed since.
The boat is a retaillers boat and was their test drive boat during the flooding.

And of the topic: Does anyone know about the hull, is there a differences between Explorers hulls in different years?

I´ll be grateful for any piece of information!

 

[ski-d00]

a 787 swap is more complicated, the engine mounts are not the same so they would need to be redone or build an adapter plate for the new mount locations, electronics are also completely different. it can be swapped but you'll need everything to go with it.

 

[Hulluhaminalainen]

Thanks skiD00, that was what I was presuming.

If I make the swap to 787 I was thinking that is it able to do it with 787RFI engine?
What is the difference between 787 and 787RFI besides the sound level?
How is the lower sound level acchieved? How different is the exhaust system?
Is the RFI engine with it´s apparels small enough to fit down the hood of the Explorer?
Do I need to have for example the whole technical package from teared down GSX RFI for example?

 

[ski-d00]

The RFI and carb 787 are basically the same in size, just a few more technical items that are fairly small so either would work for your swap. The sound level is different due to a tuned resonator, but exhaust systems are also basically the same except for the resonator toward the back where you should have room. As I recall, the explorer hoods are pretty good size so I don't think fitting would be a problem.

Yes, should have everthing. What you need is a wrecked ski with a good motor. Or, buy a beat up ski with a bad motor, then just rebuild and ditch the hull.

This is a pretty large job but can be done if you have a complete transplant. Why not use a 951 or 951DI if you are going to do it? I think it would also fit. The GSX hull is smaller than the explorer hood from looks so it should fit.

 

[Hulluhaminalainen]

I think 951 and 951DI engined jets have bigger propulsion system.
Am I right?
The propulsion system changing will be even bigger job to do.

The other problem is that it will be hard enough to find a complete 787 engine package...
What will it be finding a one with 951 or 951DI???
Wrecked craft may though be found from insurance company lists...

What would the 951 do to the Explorer if we think that it is the older version with the flat bottomed hull...
Does anyone know how many horses does the 717 create with the Factory Pipe`s exhaust?
It would be easy change to 717 if engine is the 657.