GSX 800 Jet unit (140mm) not forward enough on driveshaft?

[flyingkiwi]

HI All.
Just fully rebuilt my 1996 GSX 787 that I bought dead, all back together and done two lakes with it now. Its cavitating on start up and out of a hole. friend that sold it to me said its always cav'd. It has new carbon seal, and both rubber plugs are installed on shaft. Problem is I can look up into intake grille and see 1/2" or so of spline on the shaft and the rubber boot thats supposed to be at the impeller is way out in no mans land doing nothing. Could this be my cav problem? The wear ring and impeller are in top cond with no slip so I cant blame these. Its an Alloy unit.

 

[racerxxx]

Any chance you can post a pic? And a pic of the impeller?

 

[Kwik_uk]

Wrong shaft by P/O? Wrong motor mounts?

 

[flyingkiwi]

Just uploaded a couple of pics.
I did read the impeller and it states '13-18' or it might have been 18-13 but either way these numbers are a LONG way from the recommended pitch from Seadoo mins and max's

 

[flyingkiwi]

nothing was changed from when it didnt cavitate, except the unit was swapped to the alloy one it is, from a plastic one. the impeller pitch is also a lot less than it was previous. the shaft and engine mounts werent touched

 

[racerxxx]

Where's the rubber nose cone for the impeller. Can you post a pic of the pump, if that's an aluminum pump I don't think that will work correctly with the plastic pump support, I could also be wrong. Unless the distance is the same from the front of the hub to the mounting surface. You should have s plastic pump with a bronze inside.

 

[mikidymac]

I would say wrong pump and impeller. The pump isn’t going far enough forward because it’s the wrong one.
Your going to strip out the splines running it like that.

 

[Chester]

You have the wrong pitch impeller in there. Get the right impeller. Preferably a 17/22 Skat-Trak Swirl. The pump is ok as all 140mm small hub pumps are compatible. Also, it's normal to see a space between the driveshaft collar and the nose cone on an aftermarket impeller. The stock nose cone is a lot longer than the aftermarket ones.

Chester

 

[IDoSeaDoo]

If you try to grab the driveshaft, does it move freely in/out? If so, then your carbon seal is probably not sealing well. Have you tried running with the seat off and looking at the carbon seal? is there a swirl of water coming off it as you accelerate? How's your neoprene seal doing?