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  1. #1

    2006 FX HO cavitation problems / upgrade questions

    Hey guys,

    This is going to be a long post

    New to the forums, but have been into jet skis for about 3 years. Just bought a 2006 FX HO Cruiser with 17 hrs on it.

    I already have a 2005 VX and 2008 GP1300R that i have had zero problems. I am somewhat mechanically inclined, but will take this stuff to the shop for major repairs.

    In short, I have a cavitation problem with the pump on the recently purchased FX HO is background, my conversations with the guy that owns the jet ski shop, and some upgrade questions!

    ------Background story-----

    So, i bought the low hr FX HO, got it home, took it out next day, and it starts acting really sluggish. The toolbags at the dealership where it was regularly serviced installed the recalled engine hoses and did not fasten the clamps! Idiots. Ski filled up with water. Got air filter wet (i've replaced that with the Riva racing one). Engine had water in it, which I assume got in through the intake. Amazingly, it never stopped running, and i got it back to shore safely. (barely. the hull was full over the battery in water, and was running like CRAP. (battery is now dead, which i am going to replace with an AGM).

    I immediately (within 4 hrs) had changed the oil 10-12 times. and the oil filter twice. Went through 5x 5 quart jugs of 10w30 oil. So the oil is back on track.

    I put new plugs in it too. The stock NGK ones.

    So, i get the ski out to the lake to try to pull with it (i pull a ski/wakeboard 90% of the time with my VX, and this is the VX upgrade). And it is cavitating like crazy. Won't pull the skier up.

    Comparing it to my VX and GP1300R, which run perfectly, it is obvious that there is extra clearance between the impeller and the stainless wear ring. It is symmetrical too. The impeller appears to be in perfect shape. NO dings or anything. This is a freshwater ski. Looks to be a couple very light corrosion spots in the jet tunnel but very very light.

    ------I call the shop to get a second opinion, Dale's Jet Sports in Sachse, TX-----
    These guys are great. Lots of good reviews, etc. They race, and fully trust them.

    I tell the guy about the pump and what it looks like, and that I own two others that are in perfect running order. Basically tell him that the clearance looks larger than the OEM allowance and that it cavitates a lot on takeoff.

    He tells me to check for cavitation burns on the impeller. I don't see any.

    He says that there is definitely something wrong or it wouldn't be like that. He says they could need to rebuild the pump (put new bearings and seals in it). And from how he talked they will need to put a new impeller in it.

    Question 1: It doesn't look to me like the SS wear ring is worn. I mean, how do you really 'wear' something like that? On the impeller, is it possible that the blades are symmetrically tweaked, thus creating the larger clearance?

    --------upgrade questions------------

    Question 2: Since he will have to pull the pump, I'm going to have him upgrade a couple things since the "install" labor is basically free.

    Here is the upgrade path:

    Engine: I have the RIVA high flow air filter already installed. I am planning on modifying the intake stacks (basically drilling out the rivets of the spark arrestors and pulling the arrestor off--got this idea off of here.) instead of spending the 140 on the RIVA velocity stacks. I may also buy the free flow exhaust, but won't spend that money until i have the pump working great. So, limited bolt on engine mods.

    Intake grate. I'm thinking R & D based on my trolling in these forums. I read somewhere where someone may have broken a RIVA top loader? And some comments that the R & D just looked sturdier; that it has 2 fins instead of 1. Will I want to buy the R & D pump seal kit as well? Or does it matter if it is Riva brand? (Is the pump seal kit specific to the grate??)

    Impeller: It sounds like i'm going to need to replace the impeller at a minimum, so I'll have him put aftermarket impellar, I'm thinking the Solas Dynafly 14/20. With the limited engine mods would the 14/20 spin/cavitate at holeshot pulling the skier up?

    Thanks so much guys!

  2. #2

    Join Date
    Sep 2006
    San Diego
    There is a small foam strip between your hull and the center piece (can't think of the name) between your ride plate and intake grate which may is partially or all missing. Noticed heavy cavitation on take off which gets better if you get to higher speeds after I rebuild the pump and that little piece was the problem. Your pump sucks water from the side till your grate starts filling the pump.
    It's a $2.20 part and worth checking. I tried insulating foam first but it blew right out, so I ordered the yam part.

  3. #3
    Thanks for the reply. Is it #2 in this picture?

    I actually ordered this part from yamaha but did not install it. To fix this, do I need to pull both the intake grate (#3) and (#2) (pump shoe intake--for lack of a better word).

    I have the service manual. I believe all i have to do is pull the bolts, and then locktite them back in? (with low torque, per service manual specs)?


  4. #4
    I meant pull pump shoe #1 and intake grate #3, and then just bolt it back together???

    Thanks again!

  5. #5

    Join Date
    Sep 2006
    San Diego
    If the bolts come out easy your good, otherwise you may need to heat them up so you don't damage the bolt inserts.

  6. #6
    Thanks RBI. I went and picked up the part at lunch. I will try to get it on this weekend.

  7. #7
    Just relax and enjoy the ride. XLT Chad's Avatar
    Join Date
    Jan 2011
    While you have the pump shoe out, this would be a great time to install the pump plug kit. If you fill the voids you will have less chance of cavitation. IMO, that foam crap is a waste of time. just use some 3m 5200 when you install the PPK.

  8. #8
    volltrex's Avatar
    Join Date
    Dec 2007
    Jersey CI
    factionfx......have you checked the impellor clearance?

  9. #9
    Thanks for the info Chad. I don't have the PPK yet; actually haven't ordered it.

    I was thinking that putting the felt strip in is pretty straightforward...just unbolt the two pieces (pump shoe and intake grate==6-8 bolts), install felt strip, loctite, reassemble. Am I correct in that assumption?

  10. #10
    @volltrex, no i have not checked it with a guage. It definitely looks larger than my VX and GP1300R. (both the VX and GP1300R look the same.

    I will try to get a picture of the tunnel tonight.


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