FX-1 Cavitation!!!!!!!!! Help!!!!

[95FX1]

I have had my FX! for a few years, its always had some cavitation from day one when i got it....it has all the nice bolt on's JD plate/scoop great whatnot....
but this year i had it out once last week and the cavitation was so bad i could barley get moving forward till it gets up on plane.....do any of you get this also??
im a pretty big dude 250ish so i was kinda thinkin it might be my scoop grate not lettin water in enough till im movin forward at a good rate cause the ski is pretty far in the water in the back area....there is no problems unless im going slow...
i took the plate off yesterday just to get a good look at the pump...see if it was cracked or anyway air pocket could be getting in somehow....im new to this problem and how to go about fixing it...

LOST, please help

thanx in advance

 

[tor*p*do]

pull the pump and check the seal
if it is leaking, you will suck air
and cavitate

 

[Wave Chaser]

The stock pump cavitates even when all is good. If it grabs good once your going and your sure everything is sealed nice I would say your clearances or your prop need to be looked at.

 

[Speedfreak]

Thongbonger had the same problem. We took the pump apart a few times then sent the impeller back of to have it repitched. Ended up sealing EVERYTHING and it fixed the problem. No cavation now

We sealed the seal to the pump, seal to the hull, bolts, rideplate, every surface that touched another got some silicone.

 

[95FX1]

^^^^ Thanx for the help

gonna seal everything....and take a good look at the prop

 

[yamanube]

Ive got a skat-trak prop if you are in the market.

 

[95FX1]

i took everything apart and it all looked in perfect shape...
Great prop
not a scratch on the pump/veins or anything really!!!

so i sealed every little area i could...both side of the ring
the pump spot where it comes apart
all the bolts
the toploader and the plate

IT NOW IS PERFECT AND IS MORE RESPONSIVE THEN I CAN BELIEVE!!!!!!!!!!!!!!!!!

I LOVE MY FX1 AGAIN

MANY MANY THANKS BROS, SHE ALL GOOD NOW!!

 

[Speedfreak]

Thats great.... The same with thongbongers it helped more than we expected. I do the same with my SJ now everytime it comes apart.

 

[Shadow7874]

i took everything apart and it all looked in perfect shape...
Great prop
not a scratch on the pump/veins or anything really!!!

so i sealed every little area i could...both side of the ring
the pump spot where it comes apart
all the bolts
the toploader and the plate

IT NOW IS PERFECT AND IS MORE RESPONSIVE THEN I CAN BELIEVE!!!!!!!!!!!!!!!!!

I LOVE MY FX1 AGAIN

MANY MANY THANKS BROS, SHE ALL GOOD NOW!!

Is that a new front bumper or the purple one painted white? Im ab out to start painting some of the purple stuff for now, b ut was wondering if anything will stick to the softer bumper.

Also, how long did it take to seal it all? my ski is in my garage for the minor painting im doing but it should be in the lake in a few days, should i seal my pump? I have yet to ride the ski.

 

[95FX1]

^^^ took like a half hr to take apart every thing that can come apart....then i just ran a bead...not to thick of clear silicone between every area the connects back together.....the rubber part in the very front i would assume is the most important part to get so i sealed it on both sides....then when i was puttiing it back together i got the bolts snug then tapped it tight from the back to the front so i was sure it was not gonna get air in....then i cranked it all tight....let sit for a few hrs then put it on the water....was all good...about an HR. from beginning to end

the paint question....i used a plastic paint and plastic primer...both white....it is used to paint outdoor chairs and whatnot...got it from homedepot....works real good but will crack off somewhat....primer is the KEY.......i hate the purple

 

[curt248]

Ok so I just took off the grate intake and ride plate.

What parts exactly are you guys siliconeing? I siliconed the small indentation where the impeller meets the hull to make it flat (the circle that goes around the impeller).

I also sealed the area where the intake grate meets the hull. I think this may help the water go into the impeller better instead of creating turbulence.

I sealed the cracks where the ride plate and hull meet.

Are you guys taking apart more pieces to seal more than I did? I didn't take the pump out at all. I was thinking that the parts that create cavitation would be all before the water hits the impeller. Now that I think about it, there are probably places that could create turbulence after the impeller where the water is being pushed to.

Please help.

 

[Speedfreak]

When you pull the pump out there is a rubber seal that seals the pump to the hull. The impeller pulls the water through the hull so that seal has to be tight. If not air will be pulled into the water tract which makes the impeller cavitate. I put a bead of silicone around the pump where the seal sits then only put the seal on 1/2 way and another bead around where the seal touches the hull. Then when you bolt it on it squishes the silicone where it needs to be and glues it all together. I also seal the pump parts together wearring, stator, and reduction nozzle. (but I use a thin layer of yamabond for that)

 

[curt248]

I've read the last post 5 times, but I'm still confused.

Does the pump include the impeller? What exactly is considered the pump. I was thinking it would be the impeller and everything to the rear of the ski where the water shoots out.

Do I need to remove the entire pump to seal up the rubber seal you are talking about or is sealing the small groove where the hull meets the impeller be sufficient?

How do you remove the pump? I noticed a few hoses that appear to be in the way of the bolts that hold the pump in place (the two torwards the nose of the ski). It looks like only 4 bolts hold on the pump. Is that correct?

This seems like one of those situations where a picture could say a thousand words. lol.

 

[curt248]

Thanks for all of your help!

I found a pic of a stock fx-1 pump
So is the black part just in front of the impeller the seal you were talking about? Does the pump need to come apart to seal it up? Are there areas inside the pump itself that can (and do) create cavitation?

Where are the wear ring, stator and reduction nozzle in the picture?

 

[FX-Rex]

Where are the wear ring, stator and reduction nozzle in the picture?

Looking from left to right, they are in that order. The section that surrounds the impeller is the wear ring. The part that is stationary, but contains the bearing assembly for the impeller to rotate is the stator, and the part that reduces the pump flow and supports the stearing nozzle is the reduction nozzle.

 

[curt248]

ahh ok. Thanks for the lesson.

Soo. If I were to do the 140 or 144mm pump conversion, would I have to move the driveshaft down a bit (about a foot in front of the impeller where the shaft comes out of the hull just above the intake grate) so that the bearing doesn't wear out?

 

[yamanube]

ahh ok. Thanks for the lesson.

Soo. If I were to do the 140 or 144mm pump conversion, would I have to move the driveshaft down a bit (about a foot in front of the impeller where the shaft comes out of the hull just above the intake grate) so that the bearing doesn't wear out?

No, you align the pump to the driveshaft/midshaft.

 

[curt248]

How in the world would you do that?

I imagine you would have to bore out the hull, but how would you measure (make sure) that it is lined up properly?

 

[FX-Rex]

do some digging around, there are very good instructions on how to do the pump mod.

 

[curt248]

I've been looking. Where can I learn how to do glass work? I think that is one of the bigger stumbling blocks for me. I just don't know what can or has to be done.

The build's I've seen on here have been cool, but all seem to be lacking the step by step approach that I will need to do this job myself. Also, each build seems to do it a different way so any lack of completeness is not filled in by the others.

I'm dying to do the mod, but so far I haven't been able to bridge the gaps in knowledge to finish it. I want to know most of what is needed to know b4 I start though.

Most of you on here seem to have been doing ski work for some time. I just started and have no experience with skis at all. I've done quite a bit with cars and motorcycles though.

So far I haven't found any good soruces on how to change out the shoe for a 144mm or even a kawi 140mm. I imagine it has to be lined up perfectly, but how that is done is a mystery to me. Also how to line up the shaft seems to be missing too. I'm assuming a certain degree of precision is required.

Can anyone turn me on to a good source for this.