Results 1 to 6 of 6
  1. #1

    Join Date
    Jul 2011
    Austin Tx

    Smile 96 Wave Blaster 2 Overheating

    96 Yamaha 760 Blaster 2 runs fine low end, and top end

    full throttle wide open throttle engine will overheat, goes to limp mode , exhaust pipe sensor working cuts back to 1 cyl.

    motor will run 3 or 4 minutes idle to cool off then runs fine again did not seem to do this when new now more frequently when run very hard stays hooked up in the water pretty good in light chop then will overheat during long WOT run

    pisser oulet coolant flow seems fair but not as strong as when new ,strainer could affect it a little but didnt overheat like this then either when new.

    Has a restriction in the exhaust pipe or jacket or carbon, oil, soot, gunk buildup restricted or clogged up a cooling passage or carbon buildup in exhaust pipe? due for service ?

    cleaned top end head and cyl cooling passages when i did the top end re ring and cylinder job a few years back

    Please advise


    stock motor
    protec ride plate and intake grate
    new pump bearing rebuild and new prop solas 13/17
    wear ring acceptable
    stock oil injection
    inline weed strainer on coolant line
    Last edited by proteus; 07-11-2011 at 08:46 AM.

  2. #2

    Join Date
    Jul 2011
    Austin Tx
    Pulling pipe to check for restrictions and clean and inspect for debris initally it looks like interior chamber of pipe normal burnt oil so far will inspect/clean degrease all areas pipe today gotta pull tank which has trash in the bottom and a little water to get elbow out of hull ,clean oil tank too while its out gas was bad from sitting ,drained

    fired and ran fine but gas was stale

    so far im seeing hard water calcium deposits around some of the gasket surfaces where the small cooling port goes thru the metal gasket in the pipe will clean deburr inside slightly maybe bead blast inside a little to clean water jacket areas after i tape off gasket surfaces

  3. #3

    Join Date
    Jan 2006
    Texas City, Texas
    Are you sure that it is not running lean? Do the RPM's fade at WOT?

    I've tried CLR (Calcium, lime rust) on my cylinders and it seems to work well. I just do not leave it in there very long.

  4. #4

    Join Date
    Jul 2011
    Austin Tx

    Smile 760 Exhaust pipe cleaning & service

    No, how much clr ? Is it a caustic solution or a mild acid ? then flush / rinse

    rpm solid all the way through to top end, the pipe would get hot as heck on extended wot run thru light chop and sensor would cut in idle down 5 minutes then run again wide open this has gotten progressivly worse thru time needed to fix before i seized motor
    rebuilt pump bearings and solas last year smooth as heck now no vibrations
    carbs are probally due for some kits soon though to freshen them up
    i've had this ski since new
    time for pipe maintainance and cleaning,never tore pipe down this far before,
    tore it down yesterday after degreasing and a very careful mild deburring with 1/8 die grinder bit at small coolant port opening inside to remove calcium i found calcuim buildup at the bottom lower coolant port of the exhaust manfold which is where it goes into large manifold chamber elbow thru small 3/16" metal gasket opening
    if i tape off gasket surfaces a little bead blasting inside /or just leave old gaskets on till finished wouldnt hurt to get calcium out, calcium insulates pipe to retain heat would be much worse on a saltwater boat
    i just used a long mandel and a taper roll looks real sweet now, my only other choice would be to pull head and clean that out also but that will have to wait until after testing it should be ok for now

    Pipe R&R looks like brand new again after cleaning , inside chamber swirl patterns in oil are perfect ive die grinded /with 80 grit rolls and cleaned up the largest cooling and expansion chamber exhaust manifold runner tract with die gringer last time i did the cyl. slightly rough but flows nice
    Actually its tuned a little fat, never missed a beat runs smooth
    pipe and exhaust manifold showed calcium deposits on the bottom manifold coolant passages and in the large water ports of the expansion chamber on the pipe
    could have been slightly restricting/and insulating cooling water flow and calcium didnt help but hold heat,
    there is a small 3/16 hole on the lower exhaust elbow metal gasket between the elbow and manifold and it was a little restricted by calcium buildup on the aluminum casting on both sides

    it has been 8 years since i pulled the cyl and honed and reringed, exhaust gasket was getting bad also not much longer before it started leaking from corrosion
    this is a lake boat only also but the hard water and calcium deposits we occurring
    it should all be good after this again a little TLC and labor

    Talked to my buddy Jeff @ "Jet Ski Ranch" in Pearland Tx and he said exactly what i found to be wrong was true with his diagnosis he has done hundreds of these as salt water boats

    will post how it turns out
    also gonna replace all cooling lines with new ones and install a 3/8 outlet straight outlet pisser to replace small id yamaha one too.


  5. #5
    I fought this with a blaster 1 and after many head aches i found the problem. the 90 degree bend water elbows . fill with sand and turn hard like sand stone restricting the water flow blowing the out doesnt always work remove them and clean manually good luck

  6. #6

    Join Date
    Jul 2011
    Austin Tx
    The calcium deposits do look like sand it is liquified limestone from electrolysis will inspect everything clean all loose stuff with a small screwdriver and soak or glassbead as needed and check head for flatness and cut if needed

    talked to another veteran jet jet ski mechanic today ,said to also pull head and inspect and blow ,clean or glass bead coolant passages if needed on cyl head for calcium deposit removal, have no 90 degree fittings on coollant lines, just hard limestone lake water lucky its a lake boat and not salt water it would be worse, are there any anodes on this model ski? I dont think so, am noticing today calcium deposits inside cooling lines also gonna replace all of them while it is apart. they are overdue for replacement

    will r and r cyl head and clean every fitting or inspect and degrunge all calcium deposits in cyl water jacket tomorrow to ensure its all fresh and degrease piston tops too make like new

    Will use some CLR lime remover some to see if it will soften light deposits before i power wash parts , or glass bead, wire brush and the die grinder did a good job, a abrasive taper roll worked well with the long mandrel at getting at some of the larger concealed areas.

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