650 PJS Head Pipe Crack
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  1. #1
    Top Dog FOG's Avatar
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    650 PJS Head Pipe Crack

    I heard a strange noise today while riding at very slow speed, a metallic pop. Got back to shore and ran the ski on the stand, noticed water spraying out of crack on the underside of the PJS head pipe. I scraped some of the paint away from the crack. It runs from the underside of one PJS logo to the other side PJS logo.

    Has anyone here ever experienced this type of failure? Also, what are thoughts about repair?

    Lastly, overall dimensions appear to be same as stock 650 head pipe but not sure about coupler end diameter. Anyone with knowledge to share is appreciated.

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    I'll quit before I sit~~~

  2. #2
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: 650 PJS Head Pipe Crack

    Yikes! can you tell if the crack is just in the outer wall there, or did it crack through to the inside as well? Can you feel anything from the inside of the head pipe?

    An aluminum welder should be able to weld that exterior section up. I'd be concerned if the inner wall cracked, how it would be possible to get in there and fix that. Else you'd have water perpetually leaking through.

    If it was me, I'd just look for another head pipe. Write this up as a fluke and move onto a new clean used part. I know in this market easier said than done.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake, PWR ride plate [47.3mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, Coffmans Sizzler [48.5mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    Worx 205 intake [42.5mph gps]



  3. #3
    Top Dog FOG's Avatar
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    Re: 650 PJS Head Pipe Crack

    Hey Vett! Glad you chimed in.

    I cleaned up the area with Dremel and small wire wheel. I did not expect to find cracks extending from center out to the sides. It almost appears that there was a repair at one time but I'm no expert on welding repairs.

    I plugged the hose bibs and filled the exhaust channel with water and it do not leak down. However, after seeing the extent of the crack I have little confidence in repairing the head pipe and expecting all to be good. There is obviously something wrong with this particular casting.

    Finding a PJS replacement is unlikely without having to buy a complete setup, which is not going to happen. I checked my exhaust parts bin to see if I had a stock 650 head pipe for comparison but no luck. If someone has a stock head pipe laying around, I'd be curious to know the OD and ID of the rubber coupler end and the ID of the manifold end.

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    I'll quit before I sit~~~

  4. #4
    PWCToday.com Is My Home Away From Home BLRider's Avatar
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    Re: 650 PJS Head Pipe Crack

    Wow, what a crazy looking crack. I believe that it is fixable and worth fixing. A good welder can fix that easily.
    Never argue with an idiot, they will drag you down to their level then beat you with experience.

  5. #5
    PWCToday.com Is My Home Away From Home Bruce in SB's Avatar
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    Re: 650 PJS Head Pipe Crack

    I have had 2 crack that way that I repaired…
    The metal is so dirty being a sand casting and so much heat cycling, vibration and contamination that after a short time it cracked along side the weld again
    I even tried welding a plate over it with a little better outcome but the crack was much smaller than yours
    "Thanks" to Chris Newmiller @ Newmiller Machine

  6. #6
    Top Dog FOG's Avatar
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    Re: 650 PJS Head Pipe Crack

    Kurt, Bruce,
    Thanks for the info. Prospects for replacement look dim so I found a welder that will do the repair. I should have the part back first of next week.
    I'll quit before I sit~~~

  7. #7
    PWCToday.com Is My Home Away From Home theVetteman3's Avatar
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    Re: 650 PJS Head Pipe Crack

    Glad you found a welder. If it doesn't work out, Tim Judge is an excellent resource too. He is an excellent aluminum welder and is well experienced with handling these sort of pipes. He did some MASSIVE surgery on my Kawi 1100 oem pipe to fit in my 1100 superjet build. sliced through both walls, put a plate on, even shortened the pipe. Pressure tested and fixed a dozen pin hole leaks. His work is not cheap but he will get it better than new if it's fixable. Which it appears to be.

    That would be another recommendation. See if the welder can pressure test it and fix any leaks as he goes. Or just do it when you get it back. Plug one end and see if it holds 10psi or so.
    1985 JS550/800 "Pretty Red": Newmiller 800, Rhaas 750 pump conv. [56.3mph gps]
    2009 1100 SJ:
    Kawi 1100 build in progress
    2009 SJ MINT:
    KP steering adaptor, Worx 228 intake, PWR ride plate [47.3mph gps]
    1987 WJ650:
    6M6, JD Intake Grate, 17/20, Coffmans Sizzler [48.5mph gps]
    1994 XiR: 830cc Superstock, PJS side draft, 13/18 swirl [53.7mph gps]
    1995 SJ MINT:
    Worx 205 intake [42.5mph gps]



  8. #8
    PWCToday.com Is My Home Away From Home wmazz's Avatar
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    Re: 650 PJS Head Pipe Crack

    Sorry this is late.

    That was the 650 "Cigar" Pipe? I liked that pipe. It was easier to
    get a good combination with the longer TL for some customers.

    The problem with this repair is that it is difficult to determine if
    only the water jacket is cracked. If the water jacket is repaired
    and the head pipe is cracked, it will cause a power loss, and it
    may be junk.

    That is why it is so important to pressure test water craft pipes.
    On a hand built pipes we pressure test the pipe before you build
    the water jacket, and then pressure test the water jacket.

    When repairing pipe cracks it is important to drill each end of the
    crack to terminate the crack and prevent it from growing larger
    after the repair.


    After this head pipe's water jacket is repaired, the pee hole should
    be measured and then temporarily plugged. Possibly with epoxy, or
    JB weld. Then pressure tested at 100 to 120psi, and look for air bubbles
    coming from the inside of the head pipe.

    The same basic process is used to fix a chamber body.


    Bill M.
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    Horsepower == Speed, RPM != Speed



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