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  1. #1

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    Mar 2012
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    Kawasaki STS 750cc 1996 help!

    alright, to start with i apologize for any mistakes i make in terms of forum etiquette.

    so i have spent many hours saving for a jet ski since i was about 14 now i have finally bought myself the jet ski i mentioned above. it was not cheap for my $10 an hour 16 year old wage!

    alright the problem, i took it out and there was no water being pumped/sucked through and it over heated. when i returned home i check the compression in the cylinders and one was 150 and the other about 5... i would like some tips on what you may think it is, i really am praying for a cheap fix but if news is grim please break it to me softly :P

    also as i have guessed/hoped, if it is a head gasket (which will only cost me about $30 to fix), how do i go about removing the head cover? i have the nuts removed and hoses unplugged however i cannot remove the damn thing not to mention the impossibly annoy location and logistics of the engine!

    thanks heaps in advance guys!


  2. #2
    Did it die on you: how did you discover it was overheating? Ok well this as soft as it can be.... you probably toasted the piston and the cylinder wall (A.K.A. JUG) which is removable. If this is the case then you have two options either bore both cylinders out and put a top end piston kit in it (maybe $400??) or find a used jug and get it honed and put a stock bore piston in it, or possibly find a good used jug with a matching piston that was ran in that jug in which case you could just put it in ( around $150- $225???)

    You say there was no water being pumped through it which confuses me a little. Were you able to ride the Ski at normal speed. If so then water was most likely being circulated; but you might have had a blockage somewhere that was restricting or cutting off the flow of water. Your ski is a Kawi so it probably has a factory pisser which is the thing shooting water up in the air behind your ski; if water was shooting out of that while you were riding then you had water flowing through your motor because that is where it exits once it passes through the motor and in reality although it looks cool is actually it's intended purpose, you can also check the temp by sticking your hand in it once you know the norm of your motor and see if it's running hot or not. I don't really know anything about Kawasaki's myself but this is basic Ski stuff that I'm telling you. Just like any other ski of your age ( I also just bought a 96) it would save you a lot of pain, money , and trouble to fork up the $200 or so and re do the entire fuel system; I.E. replace all fuel line even the ones inside the gas tank if yours has those, replace or bypass the fuel selector switch ( you will need to reconnect or find some way of cutting the fuel off when storing for winter), re build you fuel pump and carbs. I would also suggest cleaning and checking the gap on your plugs and checking your thermostat which might have been the reason it got hot???? The importance of having a fully functional fuel system cannot be stressed enough. Since this ski is a 2 stroke no fuel or not enough fuel will burn up one of both of your piston, which might have been the case with you, trust me I recently fried the piston in my Polaris because it was running lean (not enough fuel) and it was running like a beast right up until it seized the piston, I did all the fuel system upgrades and set the carbs richer (more fuel) than the factory suggested to be on the safe side, I still had a problem somewhere else though and it leaned out anyway. In reality I should have done some ("PLUG CHOPS" <----- Look that up) at lest since it was my first time out ever on it to at least get an idea of how it was running but I didn't and now it is going to cost me about $600 bucks for a top end build and a case sealing. Sorry to say though if you have 5 P.S.I compression your situation looks grim.

    Your still young and it really sucks that it appears you hard earned money has been squandered but don't get discouraged. Patience is key with Jet Ski's: it is very tempting to just jump on them and have fun right off but it will cost you in the long run as I am a prime example of. I also exhausted my budget so I'm going to have to wait several months just to fix mine. If you do all the proper procedures and checks your ski will likely run well for a long time. Just browse around here some guys will be able to give you more valuable info than I just have. I would suggest pulling the head off the piston with 5 P.S.I. and seeing what the cylinder wall looks like; if it's not smooth and shiny but looks like it has scrapes all over it then you have seized the piston which does not mean it won't start and run once it's cooled off but it will cause more damage every time you start it in this condition. I see you say you can't get the head off. First double and triple check to make sure you have all the bolts loose and if your sure you do you can remove the plug and then take a small piece of wood and put it against the side of the head, then tap it with a hammer and repeat on all sides of the head, it should break loose eventually.

    Good Luck, Nick

  3. #3

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    Quote Originally Posted by nick072010 View Post
    Did it die on you: how did you discover it was overheating? Ok well this as soft as it can be.... you probably toasted the piston and the cylinder wall (A.K.A. JUG) which is removable. If this is the case then you have two options either bore both cylinders out and put a top end piston kit in it (maybe $400??) or find a used jug and get it honed and put a stock bore piston in it, or possibly find a good used jug with a matching piston that was ran in that jug in which case you could just put it in ( around $150- $225???)

    You say there was no water being pumped through it which confuses me a little. Were you able to ride the Ski at normal speed. If so then water was most likely being circulated; but you might have had a blockage somewhere that was restricting or cutting off the flow of water. I don't really know anything about Kawasaki's myself but this is basic Ski stuff that I'm telling you. Just like any other ski of your age ( I also just bought a 96) it would save you a lot of pain, money , and trouble to fork up the $200 or so and re do the entire fuel system; I.E. replace all fuel line even the ones inside the gas tank if yours has those, replace or bypass the fuel selector switch ( you will need to reconnect or find some way of cutting the fuel off when storing for winter), re build you fuel pump and carbs. I would also suggest cleaning and checking the gap on your plugs and checking your thermostat which might have been the reason it got hot???? Sorry to say though if you have 5 P.S.I compression your situation looks grim.
    thanks heaps for the quick reply, very clear and precise. not what i wanted to hear but still helpful. thanks.
    also any tips on how to get this head off/examine the body :P?

  4. #4
    Yeah I put that in that last part of my reply but it was long LOL. If your sure you have all the nuts off the head you can put a block of wood on the side of the head in various places and hit it with a hammer and it should break loose. Reason being the wood will transfer the force of the hit but not actually damage the head. Was there water shooting out of the back when you rode it?

  5. #5

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    alright the head is off, and i have only bad news. piston is destroyed, cylinder is scored and head is cracked. worst case completely, only way it could get worse if the mechanic tells me it cannot be bored and i need a new block. its unfortunate but i guess the jet ski will be better for it after the rebuild (always look for those positives!!).

    so thanks for the help anyway!

    one last question do you happen to know what the massive silver metal barrel near the engine is it seems to have piping coming from the exhaust but isnt quite part of it if that makes sense??? thats just what i make of where the piping leads so any ideas on what it is would be appreciated.

  6. #6

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    i could not even tell you if there was water coming out, i was so ecstatic to have it in water and ride a jet ski for the first time in my life (after having my license since i was 12) i overlooked it, after it died on me i noticed when trying to start it there was steam (possibly exhaust) coming out of the pisser. anyway thats history a top end rebuild is the only option now so i'll report back in about 4-6 weeks when its complete, luckily i have nice parents and a plenty of hours i can grab extra at work so money shouldnt be a problem at the moment. lets just hope i dont need that new block! from what the mechanic said it looks to cost around $600ish.

  7. #7
    steve45's Avatar
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    Quote Originally Posted by nick072010 View Post
    You say there was no water being pumped through it which confuses me a little. Were you able to ride the Ski at normal speed. If so then water was most likely being circulated; but you might have had a blockage somewhere that was restricting or cutting off the flow of water. Your ski is a Kawi so it probably has a factory pisser which is the thing shooting water up in the air behind your ski; if water was shooting out of that while you were riding then you had water flowing through your motor because that is where it exits once it passes through the motor and in reality although it looks cool is actually it's intended purpose, you can also check the temp by sticking your hand in it once you know the norm of your motor and see if it's running hot or not. I don't really know anything about Kawasaki's myself but this is basic Ski stuff that I'm telling you.

    Good Luck, Nick
    Actually, the rooster tail on the back is on Yamaha Waverunners. It has nothing to do with cooling, as it's just a plastic deflector that sticks into the jet stream that comes out of the steering nozzle.

    The Kawasaki (and I'm sure virtually all others) have a pisser that sprays a small amount of cooling water. This water will be warm/hot. I've seen it on the front and on the back, just depends on the boat.

    Rorzzer, sorry to hear about your problems. Odds are that you can have the cylinders bored, or you might get lucky and get by with just honing them. You can get an aftermarket piston/gasket set on Ebay for about $200-250. If you plan to keep the 'Ski, you might consider spending twice as much and buying Kawasaki parts. (I use Kawi parts on my Ultra, but aftermarket on my 750s).

    The cylinder behind the engine is probably the muffler/waterbox.

    Nick's right, you really need to go through the carbs. Old 'Skis that haven't been cared for usually have plugged up carbs, which run lean, which burn up pistons. Also, you really need to replace the oil lines with polyurethane hoses and secure them with safety wire so they can't fall off. You'll have to fill the hoses with oil and bleed any air from the pump before running the engine.

    Don't forget to add extra oil to the fuel during break-in!

  8. #8
    Steve thanks for the correction, as I stated I'm new to ski's and don't know squat about Kawasaki, Being a mechanic I pick stuff up quick so I knew where to get this guy started at. I apologized for the mis information about the pisser, I have not seen one on the front of a ski that wasn't aftermarket but that does not mean they don't exist. Rorzzer I would bet your problem was fuel related and that where you should start, of course after you fix the piston. It is going to cost me about $650 for a top end build on my Polaris 780 and a re-seal of the case, that is not including the $300 I already dropped re doing the fuel system, point is you put a little money in and save a lot later, you put a little in know and spend a lot now!! as me and your are finding out, good luck buddy keep us posted, You can follow my re-build here if your interested http://www.greenhulk.net/forums/showthread.php?t=171030

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