Custom/Hybrid 300 SX Builds

Liquid Graffix

Liquid Graffix

liquidgraffix
Location
In the shop or on the water
I know there are a few of us out there that will be doing 300sx builds after seeing the BOB. Since this is a first for me, I figured it might be nice to have a thread about the builds we plan on doing and those who have done them before can give their 2cents as well.

I'd like to know what problems people faced during a build like this, what works, what doesn't, and what they would have done differently????????


My plans are:

750 pump mod ??? or SJ pump tunnel mod w/ SJ pump ?? (Not sure which is easier so hopefully someone will chime in on this one)

SJ 760cc motor
Custom aluminum tube hp
Custom foot wells
Tubbies
Cold fusion Steering plate with Fat bars!


Any input anyone who has done this before can give would be a BIG help!
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Cannibal

Cannibal

Tasty Human
Location
Summit Lake, WA
Lol...well, it's not that much, but typing on my phone can get retarded, plus no spell check.

So I have the 300sx hull stripped so far, plus the bottom of a 750sx also stripped. My plan is to put the 750sx hull 2" past the bond line, essentially lengthening the 300sx hull by 3" just at the pump and ride plate, it will end up being stock one-piece 750sx bottom from pump up to in front of motor mounts. The bulkhead should end up close to where the 300sx bulkhead is. Sure, you might wonder why I'd lengthen a back flip boat, but part of it is my weight at 225lbs, plus the ease of only having to graft in one piece, not the pump and motor mount section separately. It will also leave the X2 nozzle sticking out some 4" past the back of the hull. The 750 hull will be cut to even with the plate bolt mount. In the end, who knows, I might move the back of the 750 hull forward 2" and re-position the plate mount but that will leave the X2 nozzle sticking out 6". I still have some planning to do. Either way, I plan on getting creative with the back of the hull. It will be figured out in full at the time of construction.

The engine will be my ported 750 engine with Factory Pipe. With the engine sitting with the above configuration, there is room for the 750 FP chamber to clear the gas tank, problem is, the hull doesn't seem wide enough at the hood lip to take that chamber. That might result in a little hull massaging and possibly a bit of chamber massaging. Sure it would be nice to run full Yami power, but I have all of this stuff from my X2 I'm parting and a 750 I already parted.

Pole will probably be mounted at that flat area up front, maybe fill the oil tank area to ease in doing so. I plan a stock RN pole bracket, but don't have one here yet to test fit. Stock (or stock height) bracket should help get the pole high enough to clear the area where the fuel cap is. I plan to run a Yamaha fuel filler and cap externally in the same hole as stock 300sx filler. This will fit under the pole very well. For the pole, I plan on running a custom built aluminum tube pole. That's not completely figured out yet, but for the top, I hope to have a clamp down section so I can loosen and shorten the pole as needed. Otherwise, there will probably be a lot of cutting and welding to find the right length.

These are just plans and measurements I've figured out so far. I don't know if or when I'll even get to this project, but it's on my radar. I might completely disassemble my RN and address some issues then reassemble before even touching another project. Whenever I do get to it, keep an eye for a build thread.
 
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Liquid Graffix

Liquid Graffix

liquidgraffix
Location
In the shop or on the water
Flapjack said:
Pole will probably be mounted at that flat area up front, maybe fill the oil tank area to ease in doing so. I plan a stock RN pole bracket, but don't have one here yet to test fit. Stock (or stock height) bracket should help get the pole high enough to clear the area where the fuel cap is.
Click to expand...


I have similar ideas but I'd like to use as many YAM parts as possible. I have an old SN I may end up cutting the tunnel out of to glass in this one.

Went down to a local metal shop to find aluminum for the motor mount bracket. $4 a lb for what I need. I plan on using the stock 300 mounts and then bolt the aluminum to that and re drill where the 760 will sit. We had a similar project at the shop last year that used a 550 motor and mounted it this way.

I test fit a RN bracket I had to the front of the ski and noticed the inside width of the stock 300 is a bit smaller than the stock RN bracket. The RN bracket is 8.5" wide so I will have to cut into the nose a bit to make it work. I want to use an AM bracket or fab one up that will clear the front so I don't have to cut it out wider.

I also went looking for the aluminum I need to fab up my own handle pole. I need to find out the dimensions of a stock RN pole and also the RRP. The ID of the stock RN bracket is just over 6.75"

SUBNSXR from PWC did an awesome build. Here are a couple shots he posted of his nose. It looks like a stock bracket but I don't know how he got it to look like it was sunk in because the other pic shows the surface flat....
 

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stanton

stanton

High on jetskis.
Location
atascadero,ca
haha wow you reaaaaaalllllly want to backflip dont ya
since your doing craaazy mods already can i offer a tip, move the pump and intake as far back on the hull as possible. take note of xfs and lenz1one, the hull ends where the reduction nozzle attaches to the pump
 
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WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
The second pic is basically what you end up with when you remove the stock nose piece-handlepole mount and glass over the oil tank cavity.
 
GIL

GIL

Power In The Hands Of Few
Location
Cullman AL
I have decided to go a lil diff direction. I have removed 37" from the back of my sj and threaded the prop on the back of the crankshaft.
 
Liquid Graffix

Liquid Graffix

liquidgraffix
Location
In the shop or on the water
WFO Speedracer said:
The second pic is basically what you end up with when you remove the stock nose piece-handlepole mount and glass over the oil tank cavity.
Click to expand...

Looks like he just glassed straight over it. It may be a lowered bracket that looks a lot like the stock one.... hmmmm

Here are a couple other pics I found from another build that someone did. They used the tunnel from a 750sx.
 

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509freerider

509freerider

Location
Spokane, Washington, United States
I am still not sure what I am going to do with mine. If I had a extra 750 hull it would already be chopped and grafted in. How hard would it be to just build or modify a pump tunnel? Anyone have a 750 hull layin around in the northwest? I am definatly running a kawi pump and shaft because I have extras in the shop. I will be glassing over the hood vent, removing the liner, and running the air intake through the pole.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Thats what I did on mine , I used the front half of the tunnel and made a mold for the back half, then laid glass over that.
 
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