650/X-2 cavitation?

Jpass

Jpass

Location
Orlando
I just water tested my '88 650sx after painting and rebuilding the entire ski. She cavitated really bad off the line. If I turned it side to side and feathered the throttle she would eventually hook up. It didnt do this before the tear down, so it was obviously something I did. I am not sure where to look. I sealed up the pump and everything around it with silicon, better than it was prior to the tear down.

Anyone ever experience this? Cause?
 
cookn

cookn

Kamikaze
Location
where you live
did you have the drive shaft out? I have heard that you can pull air from the engine compartment down the drive shaft tube if you didn't seal that up well. have you changed anything else?
 
Jpass

Jpass

Location
Orlando
drive shaft and pump were removed for painting. Ski ran fine prior to removing. I saw someone else post a similar issue, but it was blamed on a pump seal ring, which I do not believe is present on my ski.
 
Jpass

Jpass

Location
Orlando
come to think of it, there was a plug in the engine side of the driveshaft. It was damaged and no longer stayed in place like it originally did. Is there another way to seal this up? I dont think I will be able to find another one for an '88?????
 
Vumad

Vumad

Super Hero, with a cape!
Location
St. Pete, FL
If you are pulling air from the engine compartment, you would also be pushing water into it. Unlikely to be the problem with a dry hull.

More silicone, check the clearance b/t the prop and the sleeve (shouldn't see much light), check bearings, um... more silicone?
 
Jpass

Jpass

Location
Orlando
Vumad said:
If you are pulling air from the engine compartment, you would also be pushing water into it. Unlikely to be the problem with a dry hull.

More silicone, check the clearance b/t the prop and the sleeve (shouldn't see much light), check bearings, um... more silicone?
Click to expand...

There was a small amount of water in the hull, but several people drove the ski that day and they weren't very easy on her, so I am assuming the water came in due to their aggressive riding and tipping her on her side.
 
Jpass

Jpass

Location
Orlando
I thought I went above and beyond siliconing the crap outta this thing, but I will teatr it apart and do it again. I've installed many a pump with no issues. I actually took my time with this one, maybe thatw as the issue?
 
shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
If you siliconed the pump right...which you sound like you know what you are doing. Then its def the thru hull bearing. (I fought the same mystery cavitation on my old x2). Did you remove the bearing when you painted. Did you silicone behind it when you reinstalled it? I would proactively rebuild / replace the whole assembly as time is not nice to them. If you did not aligned you motor right, it will shred your thru hull bearing/assembly. SBT has them pretty reasonable, and they are probably the only SBT part I will ever recommend actually using. I had good luck with the 2 bearing assembiles I bought from them.
 
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Jpass

Jpass

Location
Orlando
shawn_NJ said:
If you siliconed the pump right...which you sound like you know what you are doing. Then its def the thru hull bearing. (I fought the same mystery cavitation on my old x2). Did you remove the bearing when you painted. Did you silicone behind it when you reinstalled it? I would proactively rebuild / replace the whole assembly as time is not nice to them. If you did not aligned you motor right, it will shred your thru hull bearing/assembly. SBT has them pretty reasonable, and they are probably the only SBT part I will ever recommend actually using. I had good luck with the 2 bearing assembiles I bought from them.
Click to expand...

I did not paint the inside of the hull, so the housing has never been removed. Wouldn't it leak if I just let it sit in the water? It never did when I had it out there in the lake for several hours.

Im going to have to double check everything and go from there.
 
shawn_NJ

shawn_NJ

Chasing waves.
Location
Daytona Beach
Jpass said:
I did not paint the inside of the hull, so the housing has never been removed. Wouldn't it leak if I just let it sit in the water? It never did when I had it out there in the lake for several hours.

Im going to have to double check everything and go from there.
Click to expand...

I filled the motor bay 1/2 way up with water till the driveshaft bearing housing was submerged...and water dripped out the driveshaft tube. If I started the ski up with the motor bat 1/2 full water came out alot faster.

You said you siliconed the pump properly...if so, then it HAS to be the bearing/housing. You didnt disassemble your pump/swap props when it was out correct?
 
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madscientist

madscientist

chilling with these guys.
Location
good old p'cola
kawasaki = $185 shipped

any yamaha = $175.00 + core or $200.00 w/o core

lifetime warranty on carrier and comes with new bearings and seals...

my kawie fell out of the housing when i removed it to replace it w/ our prototype ..
 
Jpass

Jpass

Location
Orlando
shawn_NJ said:
I filled the motor bay 1/2 way up with water till the driveshaft bearing housing was submerged...and water dripped out the driveshaft tube. If I started the ski up with the motor bat 1/2 full water came out alot faster.

You said you siliconed the pump properly...if so, then it HAS to be the bearing/housing. You didnt disassemble your pump/swap props when it was out correct?
Click to expand...


Pump was not taken apart. Simply removed as a unit and reinstalled. I will try and fill the hull to check for leaks near the bearing. It seems a little costly to replace, so i want to make sure it is bad before spending $185 to replace. My B1 is only $150 to replace with new unit, bearings and seals.
 
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