98xpl cavitation

[JayZ]

ok, looking for some ideas here. 98xpl with 97xp rideplate. having some serious cavitation issues out of the hole. just as i'm about to get on plane, the caviation starts. impeller is not new and has had some dings, but i've fixed it up and it is in pretty good condition. tried new wear ring with no luck. tried custom wear ring with tight clearances, same problem.

when i first got the ski, it had a slight cavitation out of the hole but would start porpoising once i got close to top speed. there seemed to be cavitation on the top end as i was bouncing off the rev limiter and saw top rpms at just over half throttle. i pulled the ride plate, trued it and shimmed it, no more porpoising (a little when trimmed up and sitting all the way back, but not like it was). now this is when i started to see the serious cavitation. the ride plate is sealed all the way around and i've tried shimming the intake (stock) to make the transition to the pump shoe as smooth as possible. nothing has helped.

now here is the kicker. if i turn hard right while accelerating, i can get on plane no problem. if i trim all the way up, i can get on plane no problem. if i trim 3/4 up, the cavitation is back.

right now the only thing i can think of is trying a new impeller. as it stands right now there is too much clearance (0.030") when i put a new wear ring in. hence the custom wear ring with tighter clearances.

any ideas would be appreciated.

thanks

[TLR]

JayZ, drop me an email to my email you used the other day with your phone number and I will call you, too much to type.

Tim

[zagger]

Please do some typing, I have same problem with my 98 XPL. Thanks .

[SURFnTURF]

It is either 1 of 2 things ;the pump isnt sealed correctly at the pump shoe or the pump shoe isnt sealed correctly at the surface of the hull.If it is the 2nd problem the pump shoe has to be removed from ski (crap job) and then resealed against the hull both inside the intake area (intake grate area)and in the rear of the ski inside the pump housing.
I had this occur on a 98xpl and air was getting in next to one of the pump mounting studs took me weeks to find the problem after changing impellers and sealing everything up which seemed like 20 times over.

[red rider]

It is either 1 of 2 things ;the pump isnt sealed correctly at the pump shoe or the pump shoe isnt sealed correctly at the surface of the hull.If it is the 2nd problem the pump shoe has to be removed from ski (crap job) and then resealed against the hull both inside the intake area (intake grate area)and in the rear of the ski inside the pump housing.
I had this occur on a 98xpl and air was getting in next to one of the pump mounting studs took me weeks to find the problem after changing impellers and sealing everything up which seemed like 20 times over.

Exactly.. No silicone around the pump seal means cavitation. Later model XP'S came with a rubber o-ring to seal the pump.

[abarrassr07]

Exactly.. No silicone around the pump seal means cavitation. Later model XP'S came with a rubber o-ring to seal the pump.

can this kill top end speed?

[water worx]

98 pumps need to be "glued" in with silicone,I use clear,it cleans up nice.

[JayZ]

forgot about this, so here is the short version. the pump is not the 98, it is the updated plastic one with the rubber seal. the cavitation went away once i put some sealant between the back side of the intake grate and the ride plate.

[96XPSS]

forgot about this, so here is the short version. the pump is not the 98, it is the updated plastic one with the rubber seal. the cavitation went away once i put some sealant between the back side of the intake grate and the ride plate.

This is where I'm thinking it is Jay. Did you run a bead accross accross the front of the ride plate, on top, where there's a sill that mates against the pump shoe?