300/440/550 Need some advice on what to do next.

[mthomps]

I want to put a bigger motor in my 300sx. I am thinking a kaw 750. What I don't know is what other parts I will need to find in order to get it to work. My dad and uncle are both wrenchers who can help me with any hull mods I need to do to make it fit. I want to get an aftermarket pump as well. I don't know if the stock drive shaft on the 300sx will work or not.

My 300sx tops out at about 30mph. I'd like a little more top speed but of course what I am after is more low end to start learning freestyle.

I am looking to be pointed in the right direction. How does a 750 perform in a 300sx hull. Yeah I would like it to be flippable but what I am really after is enough low end to learn impressive maneuverability and freestyle as well as a little more top speed. I want to spend around a grand or less.

Just looking for any advice anyone has for a newb. thank you.

 

[Joker]

im working on my conversion hull from a 300 to a 650. you would have to get a new pump housing and pump. im going to use the stock drive shaft (maybe cut back a few inches). and you would need to modify the ebox mounting plate to fit a 750 ebox. also you would have to get new motor mounts or make a custom bed plate. i am thinking about getting a cheap 650sx hull and separating the halves and putting the 300sx top and the 650sx bottom so i dont have to worry about glassing in a pump housing and motor mounts. thats just my 2 cents

 

[mthomps]

Could you elaborate more on the ebox? Mounting the motor isn't a problem because I have access to a network of people through my father who could either show me what to do or do it for me for a good price or even done on my own with my fathers guidance.

I am willing to spend money for this project to work. But again, I am very new to this. I am an athletic person who rode bmx for almost 10 years, former high school linebacker, and have been lifting iron/training since puberty prior to getting in to jet skis so I definitely want something to push my body to it's limits.

Do you and the other fellas think a 750 or any other motor in my 300 will give me that satisfaction. I would rather keep this hull and upgrade the motor because, while I don't have a lot of jetski experience, I love the handling and compact nature of this little hull and would love to have the experience of creating my own boat. But at the same time, if you think this isn't possible I would eventually get a better ski. But again, I would rather use what I have to it's full potential.

 

[N2 H2O]

It's very possible. A lot of people are using the 300sx hulls for builds because of it's size. Many of the aftermarket hulls are even based around a 300sx, like the B.O.B. Here's a link to a cool build. There have been a lot of builds lately with this hull. I might think about doing one this winter with an sxr motor. http://www.pwctoday.com/f72/750-into-300sx-231396.html

 

[mthomps]

It's very possible. A lot of people are using the 300sx hulls for builds because of it's size. Many of the aftermarket hulls are even based around a 300sx, like the B.O.B. l

That's pretty much the reason I'm wanting to do this. Do you think it would flip or roll? When I got a ski I knew I wasn't going to be able to actually do any freestyle because of my price range. I just wanted to get a ski and get out on the lake. But after reading threads and seeing what people do to these things I got really excited at the possibility to dump in a new motor and have myself a little animal. I have seen videos of people with larger motors in there 300sx's but I cannot find any videos or words on how these things actually ride. Will a 750 in this hull give you enough power to launch me off of a calm lake or even a wake?


I'm trying to decide if the end result will justify the work because this thing just runs great and has been 100% dependable (about 12 hours on the water so far) and it would almost be a shame to hack this thing up if it's not going to give me what I want. Some have told me to just save the ski and by a superjet or something in a few years. Serious freestyle skis seem to cost at least 10 grand so am I just naive in thinking I can start getting big air and what not for less than 2 grand with a 300sx with a 750?

 

[N2 H2O]

I think it's very possible to do some pretty major freestyle with a highly modded 750 dropped in this thing. To really get what you want out of it, you need to glass in a 650 or 750 pump. With it done right, it should easily be able to do rolls and possibly flips off boat wakes. Nose stabs and other stuff would be a breeze on it. To really do this right though, you need to be very handy with fiberglass because you will have to do some hull mods to fit the 750 and the pump conversion. I would also chop the hull 2" to do flips and rolls. From what I've heard, everyone that has built one really likes it and you can't beat it for the price.

 

[mthomps]

Hell yeah, you are getting me excited! 750's are all over ebay right now. I'm assuming I'll pay 500-1000 for one that runs well? What kind of mods are you talking about? For a pump I definitely want to get either a 750 pump or an aftermarket one. What would you recommend?

Literally chopping 2" inches off the haul huh? I'm not going to lie that sounds intimidating. My dad has done glass work before. He repaired a transom of a boat we used to have. I'm gonna have to do some re reading of the build threads. I believe many here have done this right?

So say I go all out and try to make this as flippable as possible, am I still going to be able to cruise with a boat set up like that? Right now throttle pinned I'm doing 30 with my 200 lb body on board. I'm assuming I'll get a top speed higher than that but will I be all over the place if I try to just cruise?

 

[N2 H2O]

You can probably find a sitdown with a 750 in it for under $750. For mods, I would do dual carbs if it doesn't already have them, Factory pipe, milled head, freestyle porting, and lightweight flywheel. Now for the pump...A 750 pump would do great. A yamaha 144mm pump would put the ski over the top on backflipping. The yamaha pumps are much better. With either pump, you will need a trim setup also. The 2" hull chop would help, but I don't think it is completely neccesary if you don't feel comfortable with it. Another thing that you will want to do is shorten the handlepole 2-3". Check out the individual build section on pwctoday.com. There are 3 or 4 build on the first page. You will be able to cruise around on it. Not many people have commented on the top end of their skis, but you should be over 50. There are so many variables that you won't know a lot of how your ski will do until you ride it. You might not even like it the first time you ride it and have to make some changes.

 

[mthomps]

Thanks for the words tbone.

I got about a month of riding left this year so I'm searching for engines now.

Would this fit? lol

http://cgi.ebay.com/ebaymotors/KAWA...Personal_Watercraft_Parts&hash=item19c91fa0bb

 

[N2 H2O]

lol you could probably make it work, but I think a 650, 750, or 701 would be better for this hull. The 1100 would take up a lot of room and would make the ski ride nose heavy, which would be bad for freestyle. The power band is also much higher on the 1100 motors.

 

[mthomps]

After reading about 50 pages of build threads there are a few things I'm worried about now.

This guys didn't turn out so well.

http://www.pwctoday.com/f72/300-sx-winter-build-125576.html

He never really talked about the performance but said the 650 he put in it was soooo LOUD his ears would ring all day after riding. I definitely DO NOT want an attention grabbing loud mouth out there. One weird thing he did was change the rear exhaust to a front or side. Why would he do that? I thought that was one of the reasons people liked this hull? I don't know if he was running a waterbox or not. I can't look at pics there even after taking the time to register. They said I need to start posting first. I'll get around to that but that's s***ty you need to spam some posts to see the pics. Anyways, I'm hoping he wasn't running a waterbox and that's why it was so loud.

Now I'm also thinking of going with a 701 because I've read a few posts now saying the power band is a lot lower than a 750. One guy was saying with a 701 you can idle into a boat wake and grab huge hops compared to a 750 you will already be going 15mph to get the serious torque.

Would the 300sx's drive shaft still work?

Thanks for being kind to a newb guys.

 

[N2 H2O]

The stock rear exhaust on the 300sx is in a bad spot and causes cavitation. You will want to reinstall a rear exhaust going straight out the back. It shouldn't be too loud with rear exhaust. The 701 definately has a much lower power band and would be much better, but it comes with a higher price. The 300sx driveshaft will not work because it will not fit the 750 or 701 pump. You will have to decide what pump you will use first and then we can help you with what driveshaft will be best.

 

[screaming440]

just some words of wisdom from an old guy thats been there done that. the mods you are talking about will be way out of your $1000 budget an require 100s of hours of work.

any conversion requires a ton of parts compatibility knowlage or a ton of ($)trial and error.

if you are going to start a project like this you need to do a bunch of research and know every combination of parts that does or does not work and how to fit them together. i you don't do this you'll endup with a costly pile of parts instead of a jet ski.

 

[N2 H2O]

lol...yeah i din't see the $1000 part...I don't think that budget is reasonable for the type of build you want to do. What I'm gonna end up doing on my build is just setting aside what I can when I can and gradually gather parts and supplies until I finally have everything I need.

 

[mthomps]

Lol. Thanks guys. I sort of knew it was too good to be true. I'm so knew to jet ski's I'm still realizing just what it takes to get the big low end on a ski. You all call it braaap right? lol. Anyways, thanks for putting me back in my place. I don't know though now. One part of me wants to just enjoy what I have for a couple of years and another wants to still stick a bigger motor in there. The only reason I even thought about doing this besides all of the conversions going on is simply that I have fallen in love with this little ski and as my first ski I can just whip it around so well. I literally love it. It has become almost an extension of me.

That said, is there any conversion I can do for a grand to at least make it stay on plane in 3-4 footers? Right now I have to pick and choose days because going against a chop I can just barley stay up with the throttle pinned. A 550 with my stock pump? I don't know what it is about this ski, but if I can stay within that 1000 dollar range and get a new motor and (possibly) a pump I'd love to do it. Even if it's only as powerful as better stock skis.

 

[cookn]

And now your in the world of jet skis. Nothing is cheap, even the cheap stuff hahaha. I really like my 550 and i can get good air off waves by charging at them . it rips for what it is and i have learned to work on and keep my ski dialed with it. Im not exactly sure how the pumps are setup in the 300 hulls but if you could fandangle a 550 pump and motor into the 300 hull without getting into to much glass work i think you would have an awesome little ski. By no means will you be flipping it, and theres people with $10 000 skis that cant flip them. The 300sx hull has a way better hood design then the 550 and i would say more freestyle oriented. There really is no limits in the world of jet skis. I remember this thread about a guy putting a bunch of different pumps in a 300 hull. I think it was called Malmecks unique 300 build in the ski build ups section. Only 50 pages of build threads is not enough yet lol. keep reading and searching for ideas that may work for you and build your ski up just the way you want it. Also top speed and freestyle type low end usually dont come together. Thats where i think my 550 is a good in between. I get good bottom with my factory half pipe and lightweight flywheel and it screams on top, so if i can spot a good wave i can hit it with speed to get air instead of relying on bottom end snap

 

[screaming440]

if your new to jet skiing starting a project like this is a pipe dream and since you just started even if you did complete it how do you know that that is even what you want.

it is clear that you want more power but anyone that has a 300 turd would. spend your 1000 bucks on somthing else like a hopped up 550 or even a stock 750. keep the 300 and if you still like it work on it while you ride your other ski.

Lol. Thanks guys. I sort of knew it was too good to be true. I'm so knew to jet ski's I'm still realizing just what it takes to get the big low end on a ski. You all call it braaap right? lol. Anyways, thanks for putting me back in my place. I don't know though now. One part of me wants to just enjoy what I have for a couple of years and another wants to still stick a bigger motor in there. The only reason I even thought about doing this besides all of the conversions going on is simply that I have fallen in love with this little ski and as my first ski I can just whip it around so well. I literally love it. It has become almost an extension of me.

That said, is there any conversion I can do for a grand to at least make it stay on plane in 3-4 footers? Right now I have to pick and choose days because going against a chop I can just barley stay up with the throttle pinned. A 550 with my stock pump? I don't know what it is about this ski, but if I can stay within that 1000 dollar range and get a new motor and (possibly) a pump I'd love to do it. Even if it's only as powerful as better stock skis.

 

[mthomps]

if your new to jet skiing starting a project like this is a pipe dream and since you just started even if you did complete it how do you know that that is even what you want.

it is clear that you want more power but anyone that has a 300 turd would. spend your 1000 bucks on something else like a hopped up 550 or even a stock 750. keep the 300 and if you still like it work on it while you ride your other ski.

You are dead on about the pipe dream dude. lol I sort of had a moment of clarity this morning when I was taking her out. A few months ago when I decided I wanted a stand up I told myself I was going to try to get an older one for 500 or less and just have fun scootin' around learning to ride and get me some good exercise. The point was a low maintenance hobby that I can throw in the water in minutes, ride an hour or 2, get her out and go on with my day.

It's AMAZING how fast that turned into dreaming up big power custom skis.

Just to talk about my '300 turd' a bit more. I know this ski is literally the turd of jet skis but I gotta say all the people who say they can't even get up on them or it takes 20 seconds to get on plane just doesn't know how to do it!

Today I had a little scare. As I was riding on my knees out of fairport harbor I punch the throttle as I got out of the no wake zone. NOTHING! I can't even get the engine above idle. So I turn around and luckily I have my dad with me today watchin on the beach. Right away he says spark plug and we go to the auto parts store, borrow a wrench and put a new one in. I get back to the lake and its like the 300 came to life and I'm cruisin at 25 mph with half throttle. The previous owner put a stainless impeller on it so I don't know if that is helping me but top speed is now about 35 on a calm lake.

Erie was one of the calmest of the year and on a flat lake I can haul around carving lines on rails in this thing now and I gotta say it's JUST SO FUN! A cool dude in a bowrider saw me riding, waved me in to him and did about 10 passes giving me wakes to jump. Gotta love a little watercraft camaraderie. Gave me a chance to work on my technique hitting wakes. I wanted to sub it sooo bad but I've already read here that if you are subbing a ski with a stock hood strap and no bilge you might be an idiot. lol. Tempting as sh*t though to try!

Now I'm thinking about modding the little 1 cylinder and taking the ski to it's limit. But here I go again always wanting more!

 

[swapmeet]

I would point you towards Melmacks build. He went in a direction that leans towards your budget. Instead of doing a ton of glass work and buying a high dollar motor, he tried to extract as much as possible from the 1 cyl, and argued that his power to weight ratio is very similar to a reinforced 300 with a 701...

This stuff is addicting, two years ago I was exactly where you are now, except I had a bigger turd than a 300, it was a '74 JS440 that amazingly had less HP than your 300 does. Now i'm on a over modded FX1 hull with a snappy 701... and I want more, a lot more.
Take your time, learn as much as you can, wait for deals to come along. I agree with the idea of putting that $1000 towards a second ski, maybe a 750 Kawi or a 650 Superjet. It might sound silly, but having a reliable spare ski to play with while you tinker with your project is the best of both worlds.

 

[mthomps]

A 440 has a twin cylinder right? I've heard that before that it is actually less power than a 300. I'll have to check out Melmacks build.