1990 Squarenose Superjet to Freestyle Machine

[1550]

I bought this Superjet at about week ago, it is 650 1990 Sj with broken engine. It has been sat like from year 1994 at broken in its previous owners garage. And there is not much hours with that ski. Motor has blown piston and also crankshaft is bad when driving without oil.

The hull is very good condition with like zero stress cracks in the hull. All roundnose superjets in here are very beaten up and found out that hull for cheap so i think i can make ski from this.

Im also thinking to make that hull look more roundish and i started to chop that hull. Also i think to reinforce ski from inside and defoam it and put bigger exhaust tube. And offcourse i had to put lines for double cooling and trimline. And cut that rear lip to make more movement for trim.

I found out that X2 nozzle and trim assembly is very good for Yamaha pump also and im using this to make it work.


At first weekend i just start to smoothening the bottom with glassfiber and also cut that rear lip and make new bondline at front to cut upper part of deck of to make bondlip same height around the nose. Also i took out that exhaust hose and peel all sticker out.

Im also trying to find some parts:
Rn Sj Pole and bracket
Aftermarket exhaust
Footholds
Camo hydroturf
Big carb

 

[1550]

I put that motor in parts and also open the pump and found out very good condition parts.

I think that flywheel can be rusted out but there is none rust. Also that impeller seems veryvery good. But what you think is that impeller good for freestyle machine? Im gonna make 701 with pipe and other parts. Also is that gap between impeller and vein section longer than newer superjets? That impeller says Skat trak and 10-18,

 

[Mouthfulloflake]

I have been told that the skat 10/18 is a really good impeller !

I have one, but I have never tried it to compare.

the build looks good, take lots of pictures!

 

[Swooperjet]

Yeah....looking good. Definately keep us updated with the progress!
I just finished up my build on my 90 SN and love it!!
Good luck!:beerchug:

 

[1550]

yes, i will take lots of pictures. I just trying that x2 nozzle and find out that will give me too much throw Also im making some sleeves to the exit nozzle to find out which size will give most accleration out of water.

Also i have a question. What it makes if i mounted that impeller closer to the veins? Will that help performance or what it makes? I think make it like setback.

I think i found a treasure when i find ski in that condition... it is like not beaten up and no rust at all in normal places. For your information at this year Finnish distributor o Yamaha take two 2008 superjets forsale in Finland. And there is like thousand lakes... Thats the reason why i am so happy to find one decent ski, even it is pretty old.

 

[Mouthfulloflake]

yes, moving the impeller closer to the veins is " cutback"

you can remove the washer behind the impeller too, thats good for a few millimeters.

 

[Pablo]

hey man, i used that impeller last year and it worked fine. i have a 95 sn 701. used a riva red pipe. all else was stock. it made o.k. bottom end, mid was great, top was good too...just not up there much. it may do better with more mods. mine looks the same as urs, cutback.

 

[1550]

So that 10-18 is good for modified engine?

 

[Foximus]

10 18 is a good impeller. I ran one for a while and it was good all around. However that being said, when I switched to my 13/16 -3mm I gained bottom, mid and top speed. The newer design is definitely superior, however for keeping what you have thats a good start. If youwanna spend a couple bucks get it pitched to 9 17 and cutback.

 

[Pablo]

10 18 is a good impeller. I ran one for a while and it was good all around. However that being said, when I switched to my 13/16 -3mm I gained bottom, mid and top speed. The newer design is definitely superior, however for keeping what you have thats a good start. If youwanna spend a couple bucks get it pitched to 9 17 and cutback.

what he said:bigok:

 

[1550]

I got mine trim assembly ready.

It is 32 degrees of throw and uses stock roundnose pumpback part and X2 trim ring and nozzle. I just weld places for bolts and straighten them with Lathe.

i think it is very good. It can give even more throw down but i will be happy with 32 degrees.

I will use outboard control cable and clutch cable from motocross bike to make movements and made some leverage mechanism inside the hull to make it easy pull.

 

[1550]

I got something done in that weekend... Still more sanding to go...

I pretty much just make new bondline in the front and after that i cut that front part in same distance. And that front parts is so heavy. Also i remove that liner of hood of and found that it is like 2/3 or 1/2 of the weight of the hood. I will replace it with paper thin prepreg carbon part. And mount it with structure glue so it wont add any weight.

Also i got first layer of topcoat on the bottom and mounted tubbies in place.


There is pretty much work still but i hope i get that hull ready for paint in next weekend.

 

[TB]

i like that nose...i have a stock rn pole bracket if you still need one

 

[1550]

More pictures

 

[1550]

i like that nose...i have a stock rn pole bracket if you still need one

Thanks for offer, i keep it in mind, i just order 2 stock pole brackets and i hope those will arrive soon, but if not i contact with you...
Its also nice to hear some feedback of own work...


I also grind of those stock mats and it is pain in the ass work. I had to use drill and wire wheel to get those of... Every place is in that black dirt after that...

 

[tor*p*do]

Very nice work!!:biggthumpup:
Looks Great

 

[1550]

Got some parts from USA today...

Complete 62T bottom end from Oxnard and intake grates and Flywheel...

 

[1550]

is it stupid make bigbore engine with stock 760 sleeves with 61x cylinder?

 

[lerott]

You need big bore sleeves for 61X cylinder.
I think stock 760 sleeves has exhaust port 2mm higher

 

[1550]

i have again sanding that Superjet hull for 14 hours... I call it a day... Also repair mine SXR hull and trying to fit that yamaha engine inside. I will post pics later.