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1994 sea doo seized

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frankyp87

frankyp87

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Hello, i am new to the forum. i have a 94 sea doo 650 that is seized. i had bought a pair of jet ski's and one was good and this one bad. does anyone have a write up of how to rebuild the top end? i have some previous mechanic experience but not too much with two cycle. i pulled the plugs and they looked pretty burnt. would anyone know if there is something else wrong with the jet ski by looking at them?
Thanks,
Frank
 

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Have you disconnected the pump from the motor to make sure it was the motor seized and not the pump? There are a lot of articles in the forum that go over doing a top end. You can look in the two stroke boat section, where I have a thread "a look inside the 787". Here, you'll see the motor taken down to the crankshaft. There are parts of your motor that the 787 doesn't have, but the basic case design is still the same. That might be a good first look, to see the pix of one of the Rotax motors torn down.
 
moisture was left in the motor. I.E. it was rode hard and put up wet. where they winterized prior to sitting? as far as top end instuctions, you can google a shop manual for your ski. i' post you links but thats frowned upon here. but find a manual, and it will tell you everything you need to know.

Welcome to the site!! :cheers:
 
You will be completely wasting your time if you do not tear that motor all the way down. Usually seized jetski motors are due to rusty crank bearings...and out of about 30 motors I have tore down, only 1...yes 1 crank was good enough to reuse.
 
Does anyone have any input about the spark plugs and why they look like they do? Also, would I be okay getting a crankshaft rebuild kit and a top end rebuild kit? About how many hours would this type of job take? Like I said before I've worked on cars but never two cycle engines before. Thanks everyone for the input so far!
 
The crankshaft needs someone that has the correct jigs and press to do it...and WSM crank kits suck.

Pull it apart before you order anything.
 
I am also new to Seadoos and have a '93 XP that seized up this fall. I took it apart this weekend to find a little piece of metal stuck in the oil port of the rotary valve cover which I believe caused the shaft gear to lose a couple teeth. Everything else looks good. Is there a way to remove the shaft from the case without a "rotary valve shaft remover(290 876 488)?
 
Whats a rotary shaft remover? Snap ring pliers and a small angled pry bar will suffice. Check the block and the rotary valve for damage. You can buy the shafts with the gears on ebay for 20-30 bucks.
 
I would not recommend prying it out. You can get the correct tool for $30

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Theres a full thread 10mm bolt with a washer and nut thru that piece. I used to use a huge socket until I bought this.
 
You have a point..but if the shaft gear is bad I replace the whole assembly I pry on them gently and I have a very long pair of needle nose pliers I use with a loop in them. Once I can get a good grip on the backside of the plastic gear they pop right out. If you have to fight with it It grab the impeller tool and work the pto back and forth til it works it's way out.
 
So for updates... I took part of the motor apart and looked at the cylinder walls and they looked good. O had put marvel mystery oil in the cylinders last week. Now that it's all back together and oiled the jet ski turns over but it kinda stops at a point then goes again and stops. Also the wires are getting really hot too. I thought it might be the starter so I took the one out of my other doo and I get the same results... when I turn it over without the plugs in it turns over fine. Quick and No stops... does anyone have any ideas as go what the problem could be? Thanks everyone!
 
Take off the pump and see if the impeller turns freely. Should take less than 20 minutes.

After that test (with pump still off)- try turning the shaft by hand to see if motor turns over. That will basically tell you if it's seizing anywhere.
Other than that please wait for others to chime in with their advice.
 
I took off the steering and the pump nozzle that holds the gear oil. Now with the shaft sticking out I can't turn in by hand bit I can with a pair of pliers on it. So I wanted to go deeper into the pump and I took off the four nuts that hold the rest of it on, but it won't come off. Is it glued on there??? It's really on there, I can't even get it to budge a little.... is there anything else other than the four nuts that hold the piece on there? The piece that is closest to the Hull......
 
Someone probably used silicone to help seal it. Take a thin blade screwdriver or putty knife and see if you can pry it from the hull.

When turning the shaft by hand, remove the spark plugs first.
 
I did remove the plugs. Should I take off the plastic cover that is on the bottom of the ski to get a screwdriver between the Hull and case?
 
yes, it will come off, its probably siliconed on, or has been stuck there for 18 yrs, but It will come off :)

and just take the whole motor apart, its only a few more bolts, and it needs to be done, its time.
 
You can use a combalong...I use an old seat belt and tie it around the veins of the pump and hook to it. I had one on so tight once I used an 18 hp scotts lawnmower to snatch it out...be careful when it comes loose it goes flying.
 
seadoodoopartsofcf said:
You can use a combalong...I use an old seat belt and tie it around the veins of the pump and hook to it. I had one on so tight once I used an 18 hp scotts lawnmower to snatch it out...be careful when it comes loose it goes flying.
Click to expand...

actually the comealong is a pretty good idea, :thumbsup:
and they're pretty dam cheap !

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