300/440/550 Js550 to yamaha 701

[Superjetter_95]

So the conversation of taking a 550 and swapping a yamaha powerplant in it, along with a 144mm pump as well, came up earlier today. so im wondering if anyone has EVER attempted this and has some useful information. We have two extra hulls lying around, and plenty of 701 blocks lying around.

Ive grown up and learned how to ride on a 550 and an Fx1. Im at home on a small ski, and since ive got the 550's i figured why not? itd be something thatd be pretty cool to have around for fun.

anyways, any help or knowledge is greatly appreciated guys :biggrin:

 

[Motorheads5]

Cheaper than a stunt hull that's for sure go for it :smokin:

 

[Superjetter_95]

oh definitely, i can dream but those ski's are never gonna be a reality for me to own.

i figured a light-ish kawi with the yamaha engine and drivetrain would produce a monster with the right add ons :brap:

 

[Superjetter_95]

also, does anyone know if its even possible to fit a 144 pump without having it stick out the bottom?

im definitely gonna have to do some measuring tomorrow at some point.

i figure ill just take the entire drive train and transfer it over, driveshaft and all.

 

[Motorheads5]

Ya know that's what the fx-1 was without the 144 pump in a sense

 

[orangefinger]

why not use a fx1 hull ??

 

[sflsurfrider]

http://www.pwctoday.com/f72/js701-140mm-pump-take-2-a-205187.html

 

[WFO Speedracer]

If you want something closer to a stunt hull take a look at a 300sx hull,wider,shorter and with more room in the engine compartment,the rear tray is also much wider,the hood design is nicer.Take a look at my build,I am putting a 650 pump in one right now and starting off with a 650 engine since I can easily upgrade to a 750-800 at a later date.Installing a Yamaha engine in that ski would be fairly simple as it just bolts in with fabbed up plates that bolt on top of the stock mounts.The 650 style driveshaft and pump mod is fairly easy to do,I think a Yami pump setup would be a lot more work to do and really not worth the extra effort IMHO.A 650 style pump with a stock SXR prop and a TBM supercone should do the job extremely well.

http://www.x-h2o.com/threads/7680

 

[Superjetter_95]

My deal is that i have three 550s sitting around, so theyre readily available. And we already have an Fx1 with the 144 pump and such done to it, so thats not needed either. My dad accomplished that without too much trouble, but it has quite a bit more room down there than the 550. Its stock pump is tiny compared to a 144 it seems. Ill have to get them side by side to tell though

So im stuck with a 550 hull and yami parts to work with, but ill make it all work. im gonna get some fitting and such done in the next few weeks to get this project started.

 

[Superjetter_95]

also, i dont have the kawi pumps available either, so thats why i was going to use yamaha. We have tons of spare parts for our skis so if anything ever breaks, it would be easily replaceable

 

[tnj4life]

Foximous knows all about yamaha power in a js hull. Ive got a ported 6m6 going in my js440. For now im just going to use a js550 pump. Your tray will have to move up for a bigger pump. Foximous grafted in a 650 pump section from a 650sx. You can cut/weld the stock motor plate to bolt the yamaha motor to it, this is what ive done. You can cram a bpipe in there or go with a cheater pipe setup, im gonna use a cheater. I too feel more comfy on smaller skis like fx1s or js which I just ride flat water.

Some say its a joke to do all this to a js and of course the fx1 is a better ski, but the reason im doing this is cause fx1s are so rare and js skis are a dime a dozen. I have 1 fx1 and it will be most likely the only one i'll own but theres js skis all in this state for nothing.

 

[Superjetter_95]

I figured the tray would have to move some, ill work around that i suppose.

And as for the motor mount, im planning on fitting the yamaha motor mounts into the hull due to us having so many extras and they are better built than the old 550 ones. Ill lay them down in the hull and glass the mounting areas for those.

The pump shouldnt be too difficult, ill probably cut the tray out completely and raise it however much it needs to be moved. If i had a 650 pump lying around i would use that, but im sticking to what we have (the less money spent the better) so im limited on certain things

 

[tnj4life]

The biggest problem with the yamaha mounts/bedplate is theyre longer than the kawi plate and it will be in the way of your battery. If you could relocate the battery it wouldnt be an issue but space is limited in js hulls.

I too think i will try to just fit the 650 pump to the 550 pump cavity and build my tray however high i need to. A 550sx driveshaft will be a perfect fit for that 650 pump, you will have to go with the 550sx/650sx bulkhead bearing housing. Im not sure how much the tray will have to raise but I know it will have to raise some. If you look at the pump mount area on the js hull you will see its flat, no raised area to cut into like the fx1.

 

[Superjetter_95]

yeah i definitely dont expect this to be an easy undertaking. We've got plenty of glass and resin around so im prepared to go all out.

And as for the battery, im sure i can come up with a way to fit it in with the yamaha bedplate.

Just gotta conquer the problems and bugs as they reveal themselves and keep on truckin

 

[tnj4life]

If you used a smaller battery it might work. Are you going to fit a 144 yamaha pump to it? I dont know of anyone thats done that.

 

[Superjetter_95]

yessir thats the plan. kawi hull with all yamaha internals. motor and electrics, pump and handling.

Im planning on basing the pump cavity off of a superjets. I may just take a foam mold of it and glass over it so i get a drop in section that will fit the 144 right off the bat. Or i may do it from the Fx1 since it is already laid out to fit the 144 and would be smaller.

Im pondering different ideas with it, just gotta figure out which one will work best. But as of right now it will fit a SJ or Fx1 intake grate and ride plate. I might end up having to redo some of the bottom to get everything lined up right. I also wonder if the drive shaft will make the pump stick out any farther. :scratchchin:

Maybe using an Fx shaft would get rid of that problem

 

[Superjetter_95]

Im also thinking of cutting it down and smoothing out the lines. Ive done this with my square nose already, and it turned out pretty good.

Heres a picture i messed with in photoshop to get the basis of what im thinking.

Drop the hood, nose, and gunwhales. Add a rrp style pole or build my own set up and thats about it

 

[Foximus]

hi.


LoL. dude. I seriously dont think you understand half the depth of what you are talking about doing.


Thats all I'll say.ancake:

 

[Superjetter_95]

I know that this isnt gonna be easy by far. The fx1 conversion to the 144 wasnt easy, and for the 550 itll probably be 20x harder by far.

As for the engine mounting and all i have no idea what ill do for that, i have looked at your build and was going to ask how you had gone about mounting yours? did you use a yamaha or kawasaki coupler?

im not thinking this will be easy at all, i know its going to be a MAJOR undertaking.

and again this is just me brainstorming. Im not saying any of what im thinking will even work. theyre just ideas

 

[WFO Speedracer]

Anything can be done,thats not the issue,the issue is should it be done.