1990 650 superjet

[hiper]

Hi Gang,

I appreciate the write ups on Superjet mods . I raced standup skiis many years ago and have rode my buddies SXR 800 recently with no problems so
I have recently purchased a 1990 650 superjet at a great price to get back into riding. What would you recommend best bang for my buck to build reliable pump gas superjet to compete against my buddy SXR 800 on the lake, or at least be close ?

Thank you in advance

 

[Mike W]

First upgrade to a 701 then start doing mods. I would suggest an ADA Head with 35cc domes, Factory B Pipe and a Hooker 9/15 prop for starters.

 

[SteveC]

What Mike W said. There’s some trickiness getting the pipe into a SN hull (gotta grind off some of those ribs on the pipe side of the hull, and dual carbs present a problem with the hood air inlets), but it’s entirely doable. Been riding two such recently built skis all week! W/@DesertSJRider Going from 650 to piped 701 in that hull was like going from chicken mcnuggets to a properly cooked filet mignon. With those yummy potatoes! Definitely install bilge if you cut the hood to fit dual carbs. It takes on lots of water! I happen to be making bilge brackets for SN, if you are interested. Need old style Rule bilge... @JetManiac has a supply.

Next model will preserve siphon bilge, if it all fits.

 

[Req]

First upgrade to a 701 then start doing mods. I would suggest an ADA Head with 35cc domes, Factory B Pipe and a Hooker 9/15 prop for starters.

This is exactly what my 91 has done to it and it rips (Coffman sizzler instead of b pipe). Dont get hung up on what motor it is as long as its a 701 or 760, they can all be built to be fast and snappy. VXR pro skis and 94-95 square nose superjets came with the single carb 61x which a lot of people love for its simplicity and bottom end punch. Couches such as the wave raider, blaster, and venture came with dual carb 62t 701s or 760s with slightly less bottom end punch but more top end. The superjet has the top end from the 61x and the bottom end from the 62t for a compromise of the two. Any of them is a marked improvement over what you have.

 

[kevbo]

You will need a complete couch engine, a good pipe, and a good impeller. That should outrun that SXR unless he also has a good pipe .

 

[hiper]

You will need a complete couch engine, a good pipe, and a good impeller. That should outrun that SXR unless he also has a good pipe .

What do people mean by couch engine and why is it better?

 

[Req]

What do people mean by couch engine and why is it better?

Couch = sit down jet ski. They are not better, they are just easier to get your hands on. I just picked up a 1100 wave venture for 250 bucks for instance.

 

[hiper]

Would 760 setup fit in square nose?

 

[Req]

Would 760 setup fit in square nose?

Both the 701 and the 760 share practically the same bottom end. Only real difference is that the cases are machine slightly more on the 760 to account for the larger sleeves and there is a second pulse line. Everything else case wise is the same casting to include the bed plate that the motor mounts attach to.

You will need your exhaust from the superjet to make it fit. Port match exhaust ports and helicoil the 760 exhaust threads, swap your 650 electronics over, mill the head to even out the compression front to rear. Keep the 760 electronics so you can do "total loss on a budget" with the zeeltronics ignition for 200 bucks later, that would spank your buddies ski into next week.

 

[hiper]

Awesome information thank you so much.

 

[Req]

Awesome information thank you so much.

If you have trouble finding a good deal on a couch you could also get a complete engine from a member here. I may have a 61x for sale in the near future.