Was this a decent deal???

[dirkdiggler]

I just bought another Superjet 650 today cause it was close and a good deal I think?? Its pretty clean and has 160 psi compression in each cylinder.
Paid $600

Bought it cause th hull is in really really good shape!!

The only thing that is wrong is that is cavitates(cavitation). What is a common cause of cavitation on a 1990 SJ650?? The impeller looks to be good with no bends or chips. Im thinking splines??? any ideas??

 

[WaveDemon]

great deal.

If the prop looks good then I'd look at the midshaft carrier leaking.

 

[dirkdiggler]

how often do the splins go bad on these skis?? The jetski has very very low hours!

 

[steveyz250fpilot]

I might have given 250 for it. I think they took you.

 

[D-Roc]

also seal the black rubber pump seal where it touches the pump shoe. if that seal leaks then i can suck air in from the area above the rideplate where the pump is. FYI i use ultra blue. (not ultimate blue hylomar) i bet that is it.

 

[Matt_E]

Splines have nothing to do with cavitation.
Look elsewhere.

 

[Snackem]

Great deal on the ski.

 

[dirkdiggler]

they guy said it runs fine and then once in a while it will cavitate and then after a couple seconds of cavitating it will go back to normal??
He figured that the splines might be stripped or something!

Im going to check the midshaft asap and reseal the pump sho!

D-Roc, what is the pump shoe thing you mentioned?? is it just the seal where the ride plate meets the hull??

 

[Mike Serlin]

how long have you been riding? If you're a newer rider then it just takes time to learn how to keep it from cavitating. It's possible there is something wrong with it but more likely it will just take some getting used to. Go ride that thing

 

[dirkdiggler]

I havent rode it yet so that may be the case, the guy had two skis, 90 superjet 650 and a 90 kawasaki 650sx so I assume he know how to ride at least decent.

 

[Snackem]

If the guy sold the SJ and kept the SX I would doubt his riding ability and I would also doubt his judgment. Unless he was selling them both and just done with riding all together.

 

[augustaf]

also seal the black rubber pump seal where it touches the pump shoe. if that seal leaks then i can suck air in from the area above the rideplate where the pump is. FYI i use ultra blue. (not ultimate blue hylomar) i bet that is it.

'90 Superjets had an issue with bad pump shoe seals, however most were changed out that same model year. Impeller could be worn. (if you can insert a .020" feeler between the impeller and the housing- it's worn) -that would be like a slipping clutch on a car. The seal mentioned is the large rubber seal between the pump housing and the stationary pump shoe in front of it. Drive shaft splines can wear if not greased every few years of use, but that's very
(!) rare. If this ski has an aluminum prop (impeller blades are green) then there's your problem - it will be seriously worn!

 

[dirkdiggler]

The guy was selling both the skis, I didnt want another 650sx so I left that behind. He bought the skis 4 years ago and never really rode them much(wife didnt like, very young children). He only bought them cause when he was younger he wanted one and now hes in his late 30's and needs to buy some couches.

I really dont think this ski was used much its whole life, impeller looks new and it was never replaced( I asked), the side matt is the original I assume, and the paint on the inside of the hull is just starting to peel off, compression is great.

The impeller is all green with no paint missing anywhere.....awsome, no need to replace.

The pump shoe seal is what the problem is most likely. How difficult to fix that bad boy??

 

[Mike Serlin]

Take a look underneith or take some pics and post them on here. If you dont see anything major then just go ride the thing. its probably fine.

 

[D-Roc]

you will have to remove the rideplate and then the pump. check the seal for damage. if the ski is used as little as you say then it will probably be in good shape but it may not be sealing. i had a new seal not seal. my pump would not compress it enough against the pump shoe (part of the hull) if it cavitates bad it will be almost unridable. best thing to do is go try the ski out and see if it is running good or not. as mentioned a striped driveshaft will give somewhat the same symptoms as cavitation in the way of the ski not moving when the motor revs up. you can examine the splines when you remove the pump if the ski is not running up to par.

 

[dirkdiggler]

I had a chance to take the ski out today.......its horrible cavitation!!

My other 91 superjet or my fx1 have never done what this 1990 superjet is doing.

Pretty much while going slow and then hitting the gas the engine seems to just rev really high and go no where?? then after maybe 8 seconds it will finally start going a little faster and then will like catch and ride like normal at higher speeds.

its seems to just happen while going slow and then hitting the throttle hard? At higher speeds it rides just like my 1991 Superjet.

Is it most likely the seal that D-Roc mentioned or any other ideas?? I sealed the midshaft housing really good so it cant be that leking air.

 

[chrisdoc0608]

check the pump seal and shoe, look at the impeller, also this is out there but it happened to me, i had a plastic reduction nozzle and it got hit with debris and put a hole in it where i couldn't really see until i got it off the ski. take a pic when you pull the pump and post it


oh yea, good deal too

 

[dirkdiggler]

how hard is it to remove pump seal and shoe?? will I have to tear up my turf to access the bolts that hold it in fom the top??

 

[chrisdoc0608]

dude take the rideplate off, unbolt the 4 bolts that hold in your pump, disconnect the steering cable from the nozzle and your cooling lines from the pump, pull it out and you will see all the answers you are looking for. the seal is a ring on the backside of the pump, it is black and rubber. the shoe is basically glued to the hull and is a BIOTCH to get off. if it is damaged im sure you will see it. like i said, just get in there and pull the stuff then take pics if you have questions.... doesnt hurt to take a peek at the manual either...

 

[tom21]

no take off the rideplate, then undo the hoses on the pump only. undo the steering cable and then there are 4 bolts at the top of the pump that bolt upwards into the bottom of the tray.

how did you seal the midshaft? you are in freshwater so this may not be an issue but in the salt the rubber that holds the seals will become seprated from the housing. which is the round thing where the driveshaft comes thru the hull. if it is bad it will let air into the pump and you are dead in the water. it can also allow water in the hull and sink you.