Early 90s whaler motor into my 90 superjet

A

Adventuredude

Location
Wilmington de
I decided it was time to bring my 1990 superjet unridden for 25 years , left outside back to life for my teen sons to ride. The engine and most accessories did not seem salvageable . I found a running 650 Yamaha motor that had been pulled out of an old whaler jet boat to upgrade to more power. I talked him down to 250 and with all accessories complete I was able to listen to it fire up on the sellers garage floor. Will this bolt directly into my old sn sj. I understand the early superjets had the wimpier shaft , will that match up to the motor I just bought ? Please help I'm more of a rider then a mechanic
 
A

Adventuredude

Location
Wilmington de
Adventuredude said:
I decided it was time to bring my 1990 superjet unridden for 25 years , left outside back to life for my teen sons to ride. The engine and most accessories did not seem salvageable . I found a running 650 Yamaha motor that had been pulled out of an old whaler jet boat to upgrade to more power. I talked him down to 250 and with all accessories complete I was able to listen to it fire up on the sellers garage floor. Will this bolt directly into my old sn sj. I understand the early superjets had the wimpier shaft , will that match up to the motor I just bought ? Please help I'm more of a rider then a mechanic
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I found an article by a guy who bought a tired whaler and he claims throttle cables ect are amazingly exactly like the waverunner 3 .
 
A

Adventuredude

Location
Wilmington de
Adventuredude said:
I found an article by a guy who bought a tired whaler and he claims throttle cables ect are amazingly exactly like the waverunner 3 .
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While the motor is out I should pull the pump and replace the bearings and bushings on the shaft , anything else recomended to do before putting the other motor in . They will be beginners at stand up but are good dirtbike, snowboarder, skateboarders . So they may get aggressive pretty quickly.
 
mikidymac

mikidymac

Location
California
Post a picture of the engine. As long as it is a 6M6 650 it is exactly the same as the superjet came with. I can't imagine the cables or wires will be the same length as the superjet because of the handpole length.

Grab the mid-shaft in the engine compartment and make sure it turns freely, smoothly and has no up and down play. If it is not smooth then pull the pump to see if it is the pump or mid-shaft. If there are any shims on the pump mounting points make sure you put them back in the same spot.
 
A

Adventuredude

Location
Wilmington de
Okay sounds good, thanks so much , I will check that out . The engine sounds strong and my strategy was even if I had to rebuild it .The 250 is worth it for the accessories, I do also need at least one motor mount so far .
 
mikidymac

mikidymac

Location
California
Just don't spend too much money on the 650 they really aren't desirable and the 701 is much better. You should be able to get a running 701 for around $500 and the ski will be worth more in the end too.
 
A

Adventuredude

Location
Wilmington de
Okay sounds good, this ski had about 4 inches of water in the bottom of it outside for 22 years . Should I do the pump and mid shaft bearing to be on the safe side while the engine is out ? What else while the engine is out , sounds like I should have posted here before I bought the 650 motor .
 
A

Adventuredude

Location
Wilmington de
Adventuredude said:
Okay sounds good, this ski had about 4 inches of water in the bottom of it outside for 22 years . Should I do the pump and mid shaft bearing to be on the safe side while the engine is out ? What else while the engine is out , sounds like I should have posted here before I bought the 650 motor .
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I just bought a gp 760 with trailer for 150 but not sure if it runs yet. Starting with the snsj then I have a 96 kaw sx 650 with mods also sitting 22 yrs with a bit deeper water in it . From my memory the sj was just as fast stock as the sx with all kinds of mods , I bought them used , nobody else in my area was really into them back then . I was racing dirtbikes and had gotten my private pilots license. So I blew one up ,kept riding the other then blew it up. Then let them sit there unfortunately.
 
A

Adventuredude

Location
Wilmington de
Adventuredude said:
I just bought a gp 760 with trailer for 150 but not sure if it runs yet. Starting with the snsj then I have a 96 kaw sx 650 with mods also sitting 22 yrs with a bit deeper water in it . From my memory the sj was just as fast stock as the sx with all kinds of mods , I bought them used , nobody else in my area was really into them back then . I was racing dirtbikes and had gotten my private pilots license. So I blew one up ,kept riding the other then blew it up. Then let them sit there unfortunately.
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A little history to reassure you that I didnt stop riding stand ups to watch golf on TV haha.
 
mikidymac

mikidymac

Location
California
The 760 would be ok but they really don't make much bottom end stock. Bottom end power is what you want on a standup. The two best engines would be a 61X 701 or a 62T/61X 701.

For the kids though, anything that runs they will have fun on. I am doing the exact same thing, bought a cheap 91' Superjet 650 that is going back together basically stock and if the kids get into it I will eventually swap in a 61X 701.
 
A

Adventuredude

Location
Wilmington de
Cool let me know if you run into any problems that we can commiserate about. Where are those 500$ 701 s a previous poster was mentioning ? Tempting, just need a pipe n it's a drop in it sounds like .
 
mthomps

mthomps

Location
Cleveland
When aligning the new engine to the midshaft try using the old motor's bedplates first. It will probably give you less of a headache when shimming it. Jetmaniac here sells shims in kits cheap.
 
SuperHumanJetski

SuperHumanJetski

keep it simple
Location
Grand Rapids Michigan
Check out wamiltons YouTube guide for aligning your motor and pump. The drive shaft from the pump goes into the midshaft. It has nothing to do with the engine. So yes the driveshaft will work. And I'm running the same driveshaft on a way bigger motor and have never had an issue. Any issues with the shaft will be caused by improper alignment. Post pictures of your new engine.

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SuperHumanJetski

SuperHumanJetski

keep it simple
Location
Grand Rapids Michigan
Here's what you need to do with the superjet... Take out the pump, turn it to see how the bearings feel. If they are effed then replace them. Take out everything in the engine bay. Check midshaft bearings by turning and feeling any play. If it's effed then replace. Soak the entire engine bay in a concoction of degreaser, simple green, Dawn, warm water etc etc and clean the piss out of it. Then reinstall pump and align it so the shaft is approximately centered in the bulkhead hole, install midshaft, all other parts, motor, align motor, etc...

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SuperHumanJetski

SuperHumanJetski

keep it simple
Location
Grand Rapids Michigan
With the new motor, I would recommend checking the compression while you have it out, opening the electronics box to see if there is any water in it, and opening up the flywheel cover to check the condition of the stator and Bendix. Also, depending on how long your new motor has been sitting, it wouldn't hurt to check the condition of the carb internals. Pretty easy to do all of this and would only require a couple new gaskets. Save headaches by doing preventative maintenance. If you need any parts hmu I have everything you'd need

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