Custom/Hybrid 300 SX Builds

Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
Just grabbed my 300 tonight. I have different plans though. Mine runs perfect so first I'm going to ride it for a while. Meanwhile, I'll be cleaning up an old race 650 guts. The 650 motor has every conceivable mod from its time, and it shows. Its pink, green and all kinds of early 90's florescent colors. But, it hauls. It leaps out of the water better than my modded 144pump FX-1 ever did. I plan on swapping the drive line all together. I chose the 650 because it already has a light flywheel and I have a new prop and grate in it. Plus, 650 motors are very underrated and I want to prove a few guys wrong by back flipping this thing. We'll see. Maybe I'll just be proving myself wrong, who Knows.
 
Liquid Graffix

Liquid Graffix

liquidgraffix
Location
In the shop or on the water
I was looking at using the 650 pump and drive shaft in mine. It looks like the pump might fit with minimal cutting into the hull. Post some pics when you get started and let me know how easy (or hard) it is with that drive line.
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
OK, will do. I have some experience with this. I did a 144mm bolt up conversion on my FX-1. That turned out great. By the looks of this job, this should be easier. I will probably have to cut out the tray and reinforce around the tunnel but other than that, it looks pretty straight forward.
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
BByamaha and I rode today. I rode the bone stock 300sx. This is one of the funnest skis Ive ever ridden. The ski has absolutely no power art all but it is so light weigh and stable that it was a blast! Once we get a little HP into this thing and a better pump, it's going to leap out of the water. I even got 3/4 around on a barrel roll today. I could have ridden it out but of coarse, no power. It's like riding a miniature stock square nose 650 but with less power. Tons of fun but could be even better. I'm even thinking of keeping this one stock for my kids and finding another to cut up. This thing runs and looks like showroom new. So much fun today. Best time on the water since the Ice cold Aprill LSFR 2 years ago.
 
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Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
Try it. You will appreciate it more. Mine was so light and nimble(Once on plane). I hope It doesn't kill that feeling with the extra weight of the 750. I'm going to try to get the most out of this little thing before I tear it up. Hopefully I will score another hull before it's too late. This is the perfect ski to get my oldest boy started in a couple years. Let me know if y'all see any more hulls out there.

Her's my ski now:

CIMG6186.jpg


CIMG6187.jpg


A little too clean to tear up just yet. The ski gods might get angry.
 
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509freerider

509freerider

Location
Spokane, Washington, United States
I want to ride mine before I go hack it! Won't start though, I think the timing is off, getting spark, Comp, and fuel? A racer friend told me he had one as a kid and it was the funnest ski he ever rode trying to convince me not to molest it by modding it out.
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
I spoke with a long time stand up dealer the other day. He said the factory timing setting is way off. One of the first things I'm doing is setting up the timing. I'm also planning on milling the head, installing a Kerker or Mariner pipe(If I can find one cheap enough), replacing the archaic carburator and then changing to a super low pitched 650 pump. I have a theory that with enough mods and a better pump, this thing might leap out of the water on one cylinder. It will never back flip on flat but who cares. Back flipping is not really a skill trick like a roll. Its all about HP and a little practice. Not what I'm going for. If I can keep the light weight integrity of this ski and still get some bottom end grunt, I'll be very happy with it.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Melmack said:
I spoke with a long time stand up dealer the other day. He said the factory timing setting is way off. One of the first things I'm doing is setting up the timing. I'm also planning on milling the head, installing a Kerker or Mariner pipe(If I can find one cheap enough), replacing the archaic carburator and then changing to a super low pitched 650 pump. I have a theory that with enough mods and a better pump, this thing might leap out of the water on one cylinder. It will never back flip on flat but who cares. Back flipping is not really a skill trick like a roll. Its all about HP and a little practice. Not what I'm going for. If I can keep the light weight integrity of this ski and still get some bottom end grunt, I'll be very happy with it.
Click to expand...

Mine turned out great, there is a build thread around here somewhere, it has a basically stock 650 engine and pump in it. The WR500 carb is a direct bolt on, no rejetting required, you need one from a 91 or 92 model boat, also you can cut a 650Sx head gasket in half , dremel a few holes and ad a couple of cooling holes and raise the compression plus its a metal head gasket, I also found an intake with a boost box that was used on the later year skis along with a K&n filter
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
Thanks, I saw your thread. Seems you started with the 550 than decided to go all out with the 650. Right? I looked for the part where you switched but couldn't find it. So, how dose it handle compared to the stock one? I mean, your adding about 30 lbs I would imagine with that 650, larger pump and prop. Of coarse, your losing weight on exhaust and drive shaft. So Dose it change the fun flicky feeling or make it even more flickable and maybe carve a bit better? I know that's a lot of ?s but I'm kinda on the fence between keeping it light and doing all the 300 mods or doing the entire swap.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Melmack said:
Thanks, I saw your thread. Seems you started with the 550 than decided to go all out with the 650. Right? I looked for the part where you switched but couldn't find it. So, how dose it handle compared to the stock one? I mean, your adding about 30 lbs I would imagine with that 650, larger pump and prop. Of coarse, your losing weight on exhaust and drive shaft. So Dose it change the fun flicky feeling or make it even more flickable and maybe carve a bit better? I know that's a lot of ?s but I'm kinda on the fence between keeping it light and doing all the 300 mods or doing the entire swap.
Click to expand...

No its still light and flickable, funny thing is I weighed all the 550 stuff I took off and the 650 driveline actually turned out to be lighter than the 550 driveline.Its due for another jump in power with a 750-800
 
Melmack

Melmack

(Timothy)
Location
New Braunfels, TX
Thanks. Maybe I'll weigh everything and see before I do the swap. I know the 44 shaft itself is about 3 times the weight of a 750 shaft. The exhaust is much heavier than stock, and the power gains for even a stock 650, 750, 800 are double or tipple. Have you been close to flipping that ski as is? Not that thats what I'm going for but I would like a real world comparison in power. How bout some video of it in action?
 
Liquid Graffix

Liquid Graffix

liquidgraffix
Location
In the shop or on the water
WFO - I wanna see your build thread! I'll do some searching, but if you have a link to it could you please post it??

I'm anxious to see how easy (or not) the 650 pump fits into the hull with out too many mods. Might be a better way for me to go than using a SJ pump...

Melmack - There was a tricked out 300SX near me for sale for $300. Had a pipe and a nice paint job ad everything.... Wonder if he still has it?
 
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