550sx to 750 "All or Nothing" build

[Myself]

I'm doing this build for a customer of mine. The plan here will be a very nice looking and running 750 conversion swap along with a 750 pump.......and full cosmetic rehab. I'm starting with a VERY clean '92 model with a good running engine. The basic swap parts are coming from a 90's 750ss donor. So here's what I'm stripping down.

 

[Myself]

As of this evening, it sits like this............"Trust me,...I'm a professional".

 

[Sanoman]

Sub’d

 

[Myself]

The 750 powerplant is totally disassembled, and the cylinders are out for a fresh bore.

 

[Myself]

The jet pump is probably one of the nicest I've ever seen. The stator vanes are clean as can be. It still had its awesome 5 blade impeller!

 

[Mobile Chernobyl]

The pink lightning graphics... gone

I bet it will be fun though!

 

[Myself]

650sx pipe vs the stock 750ss pipe. Overall length is very compareable but obviously the chamber on the 750 pipe is muh longer. Of course more cc will require more overall chamber volume. You can also see the 750 pipe has a very steep short convergent cone area. My thought on that is because typically the sit downs stay in the water. The other 750 sit downs are the same. There's not really a need for any RPM 'overrun' beyond peak power vs a stand up that's in and out of the water and revving up near (or on) the rev limiter a LOT of the time. There's more to it than that, but for this discussion we'll stop there. ANYWAY, the 750 will benefit from lengthening the chamber 2 or 3 inches. I'll need to do some mockup to see what fits in the 550 hull. I'm also planning on using the 750 exhaust manifold and headpipe. The 750 needs a bit more header length than the 650. The bulbous 750ss style headpipe section adds extra volume which basically accomplishes the same thing. I believe the Kawi engineers did that due to packaging constraints of the ss hull. It was a compact simple way for the exhaust pulses to 'see' a longer header. I've not seen anybody else use the 750 manifold but I don't see any reason not to. WHOo.....I'm exhausted

 

[Myself]

The pink lightning graphics... gone

I bet it will be fun though!

Ohhhh.........just wait! The new graphics won't disappoint. The customer had them custom made!

 

[Donatello]

Love it!

 

[WFO Speedracer]

650sx pipe vs the stock 750ss pipe. Overall length is very compareable but obviously the chamber on the 750 pipe is muh longer. Of course more cc will require more overall chamber volume. You can also see the 750 pipe has a very steep short convergent cone area. My thought on that is because typically the sit downs stay in the water. The other 750 sit downs are the same. There's not really a need for any RPM 'overrun' beyond peak power vs a stand up that's in and out of the water and revving up near (or on) the rev limiter a LOT of the time. There's more to it than that, but for this discussion we'll stop there. ANYWAY, the 750 will benefit from lengthening the chamber 2 or 3 inches. I'll need to do some mockup to see what fits in the 550 hull. I'm also planning on using the 750 exhaust manifold and headpipe. The 750 needs a bit more header length than the 650. The bulbous 750ss style headpipe section adds extra volume which basically accomplishes the same thing. I believe the Kawi engineers did that due to packaging constraints of the ss hull. It was a compact simple way for the exhaust pulses to 'see' a longer header. I've not seen anybody else use the 750 manifold but I don't see any reason not to. WHOo.....I'm exhausted

Have you checked that setup to see if it will fit in the hull, the 650 stuff is a tight fit already so much so that a lot of guys mill down the exhaust manifold for more clearance.

 

[Myself]

Nope.....will find out soon though.

 

[Myself]

Here is the 750ss exhaust manifold compared to a 650sx manifold. Overall size is VERY similar. I laid a straightedge across in a couple places.......the 750 manifold is actually about 1/8" slimmer than a 650 manifold.

 

[Myself]

And here's the 750ss manifold mocked up ready for a 650 chamber.
And I mocked up the 750 convrsion plate from RCJS @john zigler so I could try out fitment.
Then set it in place to check out exhaust fit........it seems to ft fine.
Plenty of clearance with hood in place too.
And there's still enough room for an extra 2-2.5" added to the pipe chamber.

 

[Myself]

I also got the e-box relocation bracket from RCJS. Looks like it will work just fine. The starter terminal JUST touches the rubber pipe coupler but when everything is bolted during final assembly I'm sure there's at least that much play I can find in the motor plate positioning. And it seems there is still ample room to access the battery.

 

[Myself]

After confirming that everyhing fit, I finished completely stripping the ski.

 

[Myself]

This afernoon the big brown truck brought goodies!! The plan will be reinforce all known problem areas, and glass in some tubbies.

 

[WFO Speedracer]

I don't know how much Tigershark stuff you still have laying around but the models with the stainless steel exhaust the cone is a bit longer and a bit larger in diameter , it will still fit in the 650SX rubber coupler though, it's a quick cheap fix for adding length to the stock pipe that it is not well known, I found it just like you are doing , by swapping parts and seeing what fits.

 

[Donatello]

I also got the e-box relocation bracket from RCJS. Looks like it will work just fine. The starter terminal JUST touches the rubber pipe coupler but when everything is bolted during final assembly I'm sure there's at least that much play I can find in the motor plate positioning. And it seems there is still ample room to access the battery.

Nice!

 

[Donatello]

I'm using OMX Graphics to custom make the decal kit. These guys are awesome and super easy to work with. If you need decals I highly recommend. This build is something "Myself" and I have been talking about for a long time. The graphics design comes from ideas from multiple people's input. I've owned this ski since 1996 and it comes with tons of memories. I love the work that Myself is doing.

 

[Myself]

I'm using OMX Graphics to custom make the decal kit. These guys are awesome and super easy to work with. If you need decals I highly recommend. This build is something "Myself" and I have been talking about for a long time. The graphics design comes from ideas from multiple people's input. I've owned this ski since 1996 and it comes with tons of memories. I love the work that Myself is doing.

In case anybody didn't catch that......there's the owner of this build! Welcome to the party Donatello!