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  1. #11

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    I would try and avoid thermal shock and run a richer tune up to keep EGTs down.

    Robert


  2. #12
    Quote Originally Posted by rcrisafulli View Post
    I would try and avoid thermal shock and run a richer tune up to keep EGTs down.

    Robert
    I run very conservative timing on 100 octane and I've tried anything from 11.2-12.2 wot and 20-24psi.... EGT's are constantly in the high 1400-1500*f so unless you plan on running some ms109 (almost alcohol) or some e85 good luck! Moving the timing didnt make a noticeable difference either

    Surprisingly I've talked to some trustworthy tuners and they pretty much said, yea looks good. Still scares me everytime I look at a log! Hahaha

  3. #13

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    As I have said in my past posts that I always warmed up the ski before taking it out and do a idle cooldown when ever I would stop before shutting the engine off. I always ran a T-stat and no extra cooling.

    I run a 19 psi wheel and keep the rpms at around 8300 with a Dean`s tune at 62 psi fuel pressure. I am not trying to T anyone off now, I know how most of you people feel about my methanol injection system. But this system helps out on many levels, and one of them is exhaust temperatures under a heavy load. My exhaust temps must be much lower than most, just guessing... 1250 f maybe in that area. Cracked heads can be cause by too much advanced timing, not running 91 or 93 octane on a tuned ski, shocking the engine with cold water on startup with no stat, overheating heating engine, to name a few outside of a poor head casting.

    Is there a way to make the engine become a P-trap like under our sinks in our bathrooms that holds water so no sewer gases come up from the sink? If this could be done when the engine is turned off the water in the engine block and head will not drain out and there would be water in the head holding there. Maybe a spring loaded one way check valve in the feed waterline?

    CJ
    Last edited by cjk6119; 02-15-2020 at 02:49 PM.

  4. #14
    Is it well known meth injection cools the temps? Of course. Thing is We can all guess at what we think things are doing engine wise but some of us like real data.

    I suspect they have 2 different head castings, they both have a weak spot but one is ever so slightly different then the other. I had 300hrs on one head before it cracked, my second didnt last 20, third one went on late last summer so we'll see.

  5. #15

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    Allowing these motors to idle for three to four minutes prior to shutting them down is a good idea, especially since all the block/head water drains out after the motor is shut down . I always run my ski two to three min. at idle on the trailer prior to putting it in the water also on a cold motor.

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  7. #16

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    Quote Originally Posted by mwhc View Post
    Thing is We can all guess at what we think things are doing engine wise but some of us like real data.
    Yes ... you are right for the need of real data to go by. Part of racing is a guessing game and going by seat of your pants and trial and error, fabricating products and ideas, taking calculated risks . You and I are not engineers but be buy products with problems already in them and the engineers can`t figure them out after we buy them. The people in the field usually are the ones coming up with the solution to the problems.

    What you paid to have your ski fixed is not fair, and I know the ski you own was not cheap to buy. They should do a better job of quality control.

    I think I will try a inline spring loaded one way check valve and see what will come of it.

    CJ
    Last edited by cjk6119; 02-15-2020 at 03:52 PM.

  8. #17
    Quote Originally Posted by seabrook View Post
    Do seadoos with the cc system crack heads?
    i never hear of the seadoo head cracking that goes through my friends shop, usually a exhaust valve drop or stick open on them.

  9. #18

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    Any chance these engine heads are getting pockets of air trapped in the heads from a leaking head gasket causing the head to crack?

  10. #19
    Wolf714's Avatar
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    We have about two dozen SVHOs in our group, spread among the FZ, FX and GP platform. Most with Stage 1 or 2 but a few Stage 3 as well. Not a single cracked head.

  11. #20
    speeder's Avatar
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    Quote Originally Posted by Wolf714 View Post
    We have about two dozen SVHOs in our group, spread among the FZ, FX and GP platform. Most with Stage 1 or 2 but a few Stage 3 as well. Not a single cracked head.
    it must partially have to do with the colder water here, and possibly riding in colder temps. I'm sure the majority of skis are in hotter climates, and this really isn't a widespread issue like the timing chains I think.

    For those of us that it does affect and out of warranty, it's a big worry. 3 (maybe 4) out of 4 skis is a pattern. and 2 to 3 K a shot.

    Quote Originally Posted by cjk6119 View Post
    Any chance these engine heads are getting pockets of air trapped in the heads from a leaking head gasket causing the head to crack?
    not sure how to check this.

    Can anybody post where the water drains out of the engine?

    Definitely going to make more of a point of idling down for a few minutes and letting the engine cool down before shutting it off. if this is the source of the head cracks, it would be great to be able to have some type of pump circulate water through the engine only (not exhaust) for a few minutes after shut down, like a turbo timer.

    i've read that aluminum heads are not really supposed to crack as it's more likely to warp first. this spot that it cracks at really looks like a casting/torquing problem.

    this video was posted 7 years ago. mine and my riding buddies were all on exhaust side, same spot but on different head bolts.


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