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  1. #1

    '04 F12x cavitation issues

    Hi everyone. Just joined up because I need some advice on my F12x.
    Current mods are, R&D grate, Macs stage 2 with Solas 17/29, I/C, 17PSI bleed, Greddy BOV,
    Trouble is, aside from the near-hard to get rid of cavitation on holeshot, I am getting cavitation even at cruising speeds or WOT at 65mph
    it sounds like stones rattling around at the back of the ski. However if I slide the ski sideways a little the noise/cavitation stops briefly. Ski has done only 58 hours, impeller is in as new condition, bearings/seals etc replaced last season, original Honda nose seal on shaft. Centre bearing is also good and rubber drive coupling replaced at the same time and jet unit is quiet when running out of water (no spline rattle). I am thinking that the R&D intake is too bulky in the flow of water and creating too much turbulence/air pockets and when sliding sideways it forces the water into the pump harder?? Has anyone had this also? I am thinking of cutting bars from the original and refitting it. Long story but there's all the details

  2. #2
    Forgot to say, also has a 2.5 degree wedge. Wondering if this is lifting the bow causing even more air to run down under the hull and into the intake on cruise??

  3. #3
    I just read in another forum about removing the jet unit mounting plate that is glued to the hull, and resealing it with silicon. Has anyone done this?
    Apparently air can get sucked in here if they were never sealed properly or it has failed.

  4. #4
    So just continue talking to myself, but stripped the back end down tonight. Evidence of cavitation on the suction side of impeller, not at the tips, more mid-way around each blade and about an inch in from the tip, pitting just starting to show. Pump clearance looks to be easily less than 0.9 service limit. I am using the original rubber nose seal on impeller, it protrudes quite a bit when fitted in the impeller around the outside, hard to explain but this could be causing turbulence also. Got some 3M 5200 fast cure to seal the thrust plate. Chopped out 2nd and 4th intake grate bars and polished, chuck the R&D one away. I hope this will fix this problem, it sounds like stones rattling round in the pump anywhere from 30-65 mi/hr

  5. #5
    JRINJAX's Avatar
    Join Date
    Oct 2007
    Jax, Florida
    Removing the bars will help, also the Solas 17/29 aftermarket impeller will too....

  6. #6
    Have got the Solas 17/29 impeller already. A few people have said about the sponsons creating the noise but this is definately cavitation as I can see the evidence on the impeller. Can anyone confirm if it is HP bypass around the tips of the impeller is erosion/pitting seen right at the tips? Mine is midway around each blade and 2/3rds out from the blade root, that's the best I can describe!
    Also on the rubber nose seal idea, I still have the alloy Solas nose cone, is there any way to hold them in there? It rode up the shaft the first time out so I took it off again. But in saying that, it is a lot more streamlined than the original

  7. #7
    Pulled the impeller out and had a really good look this morning. It looks at though the cavitation might be caused by bypass in the pump, the edges of the impeller are slightly pitted and follows around the blade to where I was talking about. What can I do about this? The clearance is about 0.6mm or less than 0.025in, a credit card is 0.8mm and has no chance of getting in there! Is this Solas prop crap????

  8. #8
    jlfx car audio's Avatar
    Join Date
    Jul 2011
    jackson, TN
    Ur def out of spec I think manual said clearance between .012-.022" I think I had my stock prop sent in and built up so I only had .004 " clearance and it has opened up to .009" after a few rides . It hardly cavatates now 2times on launch from standstill only

  9. #9
    Yip just had a look in manual 0.3-0.5mm or .01-.02in

  10. #10
    supermac's Avatar
    Join Date
    Dec 2005
    Mooresville, NC
    are you missing the rubber oring seal at the front of the pump?

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