Custom/Hybrid 550 motor in a 300sx hull questions

[Joecochrane]

I would like to start by saying I'm VERY new to the jet ski world so bare with me. So here is what i got a fresh js 550 fully ported polished west coast head 44mm carb west coast pipe water box and some other stuff in a beat to crap bright pink 78 hull and a very clean bone stock 89 300sx. I wanna swap the motor into the sx I know its been done Just curious what i will need to do. Modify the drive shaft? can i get a smaller tank and use my front exit exhaust? How will the tiny pump handle the added power? And will I need to do any glass work?

 

[Liquid Graffix]

We did the same thing last summer. We had to use aluminum to make move the motor mounts to get the drive shaft to line up. We used a floating driveshaft from a seadoo and a 550 pump. You can use the 300 pump, but imo it's too small for that motor.

My personal project right now is putting a SJ motor and pump into my 300sx. I've gone all out and cut the hull to fit the new piece in. Not sure how experienced you are with working with fiberglass or how much work you want to do, but anything is possible. There are some great threads on here with plenty of pics. Just research it before you start cutting.

Where in SoCal are you?

 

[Joecochrane]

Thanks for the reply and I have been doing a ton of research. Do you have any pics of your motor mount setup? what seado did you get the shaft from? What mods are needed to make the 550 pump work? I build custom rock crawlers I'm a fab guy I can build anything out of metal but i have never touched a piece of fiberglass in my life. So I am a little intimidated by this project.

 

[Joecochrane]

Oh by the way I'm just outside Temecula me and my cousin go to the back side of canyon lake about once a week If any ones down (punk ass kids D bags or any one that liters are NOT WELCOME!! we got a good thing there and don't want to get shut down)

 

[SkiDiggity]

Heck yes i loved canyon lake i was down there with people off of this site in september . Loved every bit of it. Rich if you don't have pics of dan's ski next time i head up there i can take some.

 

[Joecochrane]

I've been there every day I could since last June been seeing a lot more rangers and police out there

 

[Liquid Graffix]

I'll post up some pics when I get home tonight.

I'd love to check out the lake.

 

[Joecochrane]

where are you at

 

[Liquid Graffix]

Fullerton

 

[WFO Speedracer]

I believe the 900ZXI shaft is the one you want, also the stock rear exhaust has to go, it makes the pump cavitate like crazy, just run a new thru hull tube out the back.The aluminum plates are just 3/4" thick plates drilled and tapped t bolt down to the stock engine mount holes , then drilled and tapped for the new engine mounts. There are some pics on my 300sx build thread.

http://www.x-h2o.com/threads/7680-300sx-build&highlight=

 

[Joecochrane]

Thanks I read your entire build thread pics were kinda hard to make out though. Is a new shaft mandatory? and will i have to do any machine work the 900zxi shaft. Planed on ditching the rear exhaust just for simplicity. I am trying to keep glass work and fab work to a minimum

 

[Liquid Graffix]

Here is my build thread with pics. (keep in mid, I'm doing a completely different pump area ad motor set up, but you'll get an idea of whats under the skin of the ski that you have to work with)

Just and fyi... the glass on the 300 is really thin! I would definitely reinforce it!

http://www.x-h2o.com/threads/88786-My-760-SX-(A-300-SX-transformed-from-a-SJ)&highlight=

 

[Joecochrane]

I know I will need to reinforce the hull but i would like to get the motor in and running with the stock pump first take it out for a couple test rides before I tear it all down for paint and glass work

 

[Liquid Graffix]

If you decide to do a pump housing switch and want to use the rear of a 550, I have an extra hull that I don't need. You're welcome to it

 

[Joecochrane]

Thanks man really appreciate the help I think i got a lot to learn before I cut a pump housing out and try to glass a new one in.

 

[WFO Speedracer]

Yes a new shaft is mandatory, the 440 style pump which is what is in the 300SX has the prop screwed to the shaft, 550's 55SX's 650's and 750's are set up with splines that go into the impeller and the prop screws onto a shaft inside the pump, you will need the 550SX style pump and a 900ZXI shaft, you could possibly also use some other shaft depending on how far back you want the motor to be.

 

[Joecochrane]

I was planing on running the 300 pump with a lager prop for now. I know this is retarded but I'm trying to get it running asap and keep in mind I'm so new to the sport I wont know what I'm missing out on. So to run the 550 motor to the 300 pump will i still need the zxi
shaft.

 

[WFO Speedracer]

You will never get good results with the 440 style pump, I chased and chased my tail for years trying to make that pump work, if you are not willing to do at least a 550 pump swap just leave the 300 in it and ride, it will probably work better.

 

[Joecochrane]

You will never get good results with the 440 style pump, I chased and chased my tail for years trying to make that pump work, if you are not willing to do at least a 550 pump swap just leave the 300 in it and ride, it will probably work better.


Well that kinda sucks to hear. I do plan on swapping out the pump just kinda wanted to get the motor in and running first. Will the 550 pump handle a modded 650 or 750 I plan on going that route in the future. Right now I'm trying to piece something together with the parts I have and very little money out of pocket.

 

[Liquid Graffix]

Yes you can run a 550 pump with a 650/750 motor. People do this swap all the time. You'll need a good prop.
Not the ideal set up, but workable.