300/440/550 550 to 750 Motor swap Rumor

[Mark Gomez]

Whats up everyone i heard a rumor a 750 sxi Motor will fit beautifuly into a 550sx hull with the swap of the couplers. is this true? and if so can it fit and support mods for the motor ie pipe and carbs what not.
let me know!
thanks
-Mark

 

[Jr.]

Yes, it can be done, I have done several. But as always it's more complicated than what was told you. I'st thing is the need for a jetcraft engineering bed plate converter, This is so a 750 motor will sit on the 550 bed pan. then the couplers come into play. You will need to adapt the 750 ingition box into the 550 hull. The pump will also need to be modified. The easiest is to install a 550 sx drive line (91-94) If the earlier model is used, you will need to have a thru hull support installed. those were made by either PJS or westcoast. The final piece of the puzzle is the exhaust. You will need to adapt a k650 exhaust to work on the 750. again the PJS or westcoast will work best. But expect to have cutting & welding as part of the install. All in all a fun project........
Little boats like that are crazy fun rideing at the speeds achivable, with that motor.....

ski ya, Paul

 

[63chevyll]

i would love to do that.

dont we all have a soft spot in our hearts for the 550's or is it just me?

 

[Mark Gomez]

Yes, it can be done, I have done several. But as always it's more complicated than what was told you. I'st thing is the need for a jetcraft engineering bed plate converter, This is so a 750 motor will sit on the 550 bed pan. then the couplers come into play. You will need to adapt the 750 ingition box into the 550 hull. The pump will also need to be modified. The easiest is to install a 550 sx drive line (91-94) If the earlier model is used, you will need to have a thru hull support installed. those were made by either PJS or westcoast. The final piece of the puzzle is the exhaust. You will need to adapt a k650 exhaust to work on the 750. again the PJS or westcoast will work best. But expect to have cutting & welding as part of the install. All in all a fun project........
Little boats like that are crazy fun rideing at the speeds achivable, with that motor.....

ski ya, Paul

well freakin sweet i have a 1994 with that pump now i know a guy whos selling that converstion plate on ebay. if i get that and get one of those engines and get a factory pipe and some good reeds and a steeper prop and myself being 120 pounds would that hull want to jump out of the water?

 

[Mark Gomez]

i would love to do that.

dont we all have a soft spot in our hearts for the 550's or is it just me?

You are absolutely not alone except on my budget my whole heart is soft for em

 

[jeepmark4x4]

I have done a 440 to 650 conversion...PJS dry pipe, ocean pro head, this thing ripped! But you do run into many many issues that people do not tell you about. In the end it cost just as much to fix up a SN with a 61x as it did the 440/650...And im sooo much happier with the SN

 

[ang4th]

just finished a 440-650 conversion .. used the conversion plate off ebay from freshwatercraft .. also used a westcoast pipe .. I think a factory pipe would be too fat and you will have problems fitting it in the hull .. I am using a 440 pump with hull bulkehead suport .. you dont need to do any cutting and welding I dont know what he means by that unless it is to get the 750 electronics box to fit .. with a 650 engine all I had to do is swap the regulator and then use the 550 CDI .. you could also use a 650 stator and flywheel on a 750 engine ..

 

[Mark Gomez]

just finished a 440-650 conversion .. used the conversion plate off ebay from freshwatercraft .. also used a westcoast pipe .. I think a factory pipe would be too fat and you will have problems fitting it in the hull .. I am using a 440 pump with hull bulkehead suport .. you dont need to do any cutting and welding I dont know what he means by that unless it is to get the 750 electronics box to fit .. with a 650 engine all I had to do is swap the regulator and then use the 550 CDI .. you could also use a 650 stator and flywheel on a 750 engine ..

hmmm thats reallly interesting nice work but does that engine have the power to get that hull out of the water?

 

[Mark Gomez]

I have done a 440 to 650 conversion...PJS dry pipe, ocean pro head, this thing ripped! But you do run into many many issues that people do not tell you about. In the end it cost just as much to fix up a SN with a 61x as it did the 440/650...And im sooo much happier with the SN

oh good point what issues might you be talking about

 

[Mark Gomez]

Yes, it can be done, I have done several. But as always it's more complicated than what was told you. I'st thing is the need for a jetcraft engineering bed plate converter, This is so a 750 motor will sit on the 550 bed pan. then the couplers come into play. You will need to adapt the 750 ingition box into the 550 hull. The pump will also need to be modified. The easiest is to install a 550 sx drive line (91-94) If the earlier model is used, you will need to have a thru hull support installed. those were made by either PJS or westcoast. The final piece of the puzzle is the exhaust. You will need to adapt a k650 exhaust to work on the 750. again the PJS or westcoast will work best. But expect to have cutting & welding as part of the install. All in all a fun project........
Little boats like that are crazy fun rideing at the speeds achivable, with that motor.....

ski ya, Paul

do you by chance have any pictures of those ski's completed im curious to see how it all fits mostly how you got the electrical box to fit and where

 

[ang4th]

hmmm thats reallly interesting nice work but does that engine have the power to get that hull out of the water?

ahh yea it might .. what do you think ..

 

[Mark Gomez]

ahh yea it might .. what do you think ..

well i dont know thats why i asked ive only ridden a 750 once 2 years ago long before jetsking became my life hobby so i really wouldnt know

 

[dbrutherford]

JR is right, it ends up being a bigger headache and hassel then to just fix up a nics SJ or other ski.

I put a 750 SS into my 91 650 SX some years back. The swap on that ski was pretty simple.

Here is what you will need to do to make it fit a 440 or a 550:

1.) 440/550 Bed Plate
2.) 650/750/800 Engine to 440/550 Bed Plate Conversion Plate (eBay)
3.) 650/750/800 Engine (Cases, Crank, Cylinder, Head, Intake Manifold, Carbs, F/As, ect...
4.) 650 Kawasaki Exhaust Manifold
5.) 650 Kawasaki Exhaust Pipe (Smaller The better!, it needs to fit in the ski! the stock one is pretty tiny. So is the PJS, Mariner, and Kerker. The Coffman and Factory pipe are probably waytoo big
6.) 650 or 750 Electrics (Flywheel, stator, CDI, Voltage Regulator, ect...)
7.) If you use 650 electrics, you will have to have the cases drilled and tapped for the 650 stator mounting screws and have a hole drilled through the cases for the cable to pass through them. This is stock on a 650. The 750 and 800 engines have the bosses cast into the cases where this needs to be done. Search around, this topics has been covered many times.
8.) Use the water box that came in the original hull.
9.) I am unsure of the drive shaft issues with your ski/hull in my 650 I just used the 650 shaft

It really isn't that hard to do a 750/800 into a 650. On the 440/550 there is a little bit more work to do. Things will be difintely cramped in the engine compartment too. I am unsure what you need to do about the drive shaft support, I never owned a 440/550. I do know that people swaped pumps and drive shafts from different years because some were better.

Also keep in mind, no matter how much power you have, if you cannot get it to the water, you won't be going that far out of the water. I expected my ski to jump ten feet out the water yet is barely got 2 feet on flat water. Still though, I am going to put an 800 SXR engine in my X2 when I get the funds....

DAVE

 

[Mark Gomez]

JR is right, it ends up being a bigger headache and hassel then to just fix up a nics SJ or other ski.

I put a 750 SS into my 91 650 SX some years back. The swap on that ski was pretty simple.

Here is what you will need to do to make it fit a 440 or a 550:

1.) 440/550 Bed Plate
2.) 650/750/800 Engine to 440/550 Bed Plate Conversion Plate (eBay)
3.) 650/750/800 Engine (Cases, Crank, Cylinder, Head, Intake Manifold, Carbs, F/As, ect...
4.) 650 Kawasaki Exhaust Manifold
5.) 650 Kawasaki Exhaust Pipe (Smaller The better!, it needs to fit in the ski! the stock one is pretty tiny. So is the PJS, Mariner, and Kerker. The Coffman and Factory pipe are probably waytoo big
6.) 650 or 750 Electrics (Flywheel, stator, CDI, Voltage Regulator, ect...)
7.) If you use 650 electrics, you will have to have the cases drilled and tapped for the 650 stator mounting screws and have a hole drilled through the cases for the cable to pass through them. This is stock on a 650. The 750 and 800 engines have the bosses cast into the cases where this needs to be done. Search around, this topics has been covered many times.
8.) Use the water box that came in the original hull.
9.) I am unsure of the drive shaft issues with your ski/hull in my 650 I just used the 650 shaft

It really isn't that hard to do a 750/800 into a 650. On the 440/550 there is a little bit more work to do. Things will be difintely cramped in the engine compartment too. I am unsure what you need to do about the drive shaft support, I never owned a 440/550. I do know that people swaped pumps and drive shafts from different years because some were better.

Also keep in mind, no matter how much power you have, if you cannot get it to the water, you won't be going that far out of the water. I expected my ski to jump ten feet out the water yet is barely got 2 feet on flat water. Still though, I am going to put an 800 SXR engine in my X2 when I get the funds....

DAVE

wow alright thats alot to do but it helps get the process started. thanks alot good luck with the sxr motor in that x2 thats going to be sick. But yeah the super jet is always on my mind but i can barely afford the little mods and wingdings im doing to my ski as it is right now usually big buy sell stunts when i really need the money for something.. thats when i just need to know what it is im getting lol
thanks again
-Mark

 

[jeepmark4x4]

Check it....look at that pipe...man I wish i still had that thing, I have never ever seen one like it, its a PJS drypipe for there 800 motor.

 

[cdpcb]

I talk to owner of jetcraft before he pass away ,he said run 550 pump with like 18 deg prop,still have adp.I did mock up at one time in 550 hull
pjs 700 kit
factory pipe (need to flatin on one side)for 650
west coast big fuel tank
everthing fit fine

later cd

 

[dbrutherford]

I believe Gordy was selling a manidolf and head pipe just like the pic you posted. The head pipe 180's towards the front. It is backwards from other 650 pipes.

DBR

 

[ang4th]

well i dont know thats why i asked ive only ridden a 750 once 2 years ago long before jetsking became my life hobby so i really wouldnt know

well if a 550 can pull the hull out of the water why wouldnt a 650 with aftermarket upgrades ? I dontget what you are saying ?

 

[Mark Gomez]

well if a 550 can pull the hull out of the water why wouldnt a 650 with aftermarket upgrades ? I dontget what you are saying ?

i meant that i really didnt notice how the engine pulled and performed and i know a 550 can pull out off the water but how much of a bottom end torque power do you get off of a 650 compaired to a 750 swap

 

[sjaholic]

this is the first 550/650 i built. started out running a westcoast pipe, but they are crap. went to a modified stock 650 with a long cone.

on my current conv ski i'm running a factory pipe, sx pump, 19 prop,ported cases and cylinder, 205 lbs comp, aluminum flywheel and more.

heres a pic of the first one with the modded sx pipe.