1997 Sea Doo GTI 717 Blown Piston Ring

[RobCarmines]

I have 60 PSI compression on the back piston and 125 on the Front. It is an SBT engine. I have pulled the head and can clearly see the ring with about an inch gap on the second cylinder. The piston looks pretty good, the dome (where the spark plug is) looks good and the cylinder looks great. No detectable scarring or gouges. How hard is it to put a new ring on the piston and replace the cylinder without pulling the engine from the jet ski? It is a 97, and I have put about as much money in it as I want to put. If I can rebuild it myself, I will keep it for a second ski. (I have already decided to get an end of season replacement ski). Any thoughts would be greatly appreciated. Also, it looks like I have to pull the tuned pipe assemble to reach the bolts for the exhaust. Any way around that? Anything else I have to pull off to pull the cylinder? Finally, since I am not planning on pulling the pistons off, I assume I will be fine to put the cylinder back on and not have to do most of the alignment crap. Yea or Nay?

 

[nswillin]

Hey Rob. When I rebuilt my 951, I started in the mind frame that I was gonna do it in the hull. Then after I started taking things off I realized it was gonna be so much easier to pull the engine out. You pretty much have everything off anyways when you get to where you can pull to cylinders off. Extremely glad I pulled the engine though b/c I found the root cause of my problem and with everything out you can do whatever you want to it since you got all the room in the world.
If you do plan on tackling this yourself I would recommend you getting a shop manual. That way you can get specific instructions and tech. data for what your doing. :cheers:

 

[derek]

agreed. after you get the motor down to where you can do jugs, you are about an hour's work from having it on the bench. also, a whole lot of 720's in 96-97 had uncaged rod bearings. that means when you remove the piston, ( and the piston is SHOT SHOT SHOT) ( i could use I instead of O) 34 tiny needle bearings are gonna fall into the crankcase. have motor out and on it's side and this won't be an issue. a piston costs about 70 bucks. the rings cost about $50. there is no way you can lose any of the ring without the piston being destroyed.

 

[RobCarmines]

Pulled it apart

I pulled apart the tuned pipe, cylinder heads, etc and got to the piston pretty easily. I removed the clip ring on the piston, but can't get the rod out of the piston (ie the cross rod which holds the piston in place), BTW the cylinder is clean as a whistle so I am just getting a piston/ring kit and just replacing the piston head and the rings. I'll let you know how it turns out.

 

[nswillin]

I used a piston pin puller. I borrowed one from a friend but I've seen them for sale for not more than $20 at parts stores or motorcycle shops. It will pull that wrist pin right out. But.....as Derek mentioned, be really careful that you dont drop any of those little needle bearings into the bottom. Stuff w/ rags and pull pin slowly catching bearings with magnet bowl or tipping like Derek said. Also better order new wrist pin bearings with your pistons, the new ones are fully caged and will be easier to install. Putting those cageless needles bearings that you take out back in would be a huge pain, if there even worth reusing, usually the washers that hold them get bent anyways when you remove the wrist pin.

 

[RobCarmines]

Viola

Got new piston and rings from SBT. Replaced the old piston and reassembled nead, etc. Now I have 125 PSi on both pistons. Tomorrow am I am putting the tuned pipe assembly back on and will fire that baby up (making sure that I follow the break in procedures).

 

[RobCarmines]

Almost there

WQell, I got it running and it sounded great. Then I took it to the river. It would not run more than a high idle without cutting off. SBT recommended that I rebuild the carb. I took the carb off tonight and will investigate rebuild tomorrow. I am seeing some posts that imply that the Carb may be the problem. (Still get 135 psi on both cylinders). Anyone have any experience with this problem?

 

[RobCarmines]

Carb Rebuilt

Well, I got a carb rebuild kit and rebuilt the carb. I put it back on and the engine runs. Obviously I need to adjust it now. Any tips would be appreciated. I am pretty sure I did the rebuild correctly.

 

[timmyboy76]

hey..set the low speed adj. to 1, and high speed adj. to 1.5...

 

[capone2841]

you want to close that high speed all the way off..a good start point on the low is 1 full turn out...if you find the ski is bogging after running for 15 mins then lean it out 1/4 turn back in...there is a good post on carb rebuild if you do a search for it...also if you have the old gray fuel lines you need to replace them asap..there is a inner liner in the old fuel lines that gets brittle and breaks free only to clog up your carps...

 

[RobCarmines]

Success???? Wobble now the problem.

Well, I rebuilt the Carb, adjusted the low speed (i think) and the High Speed (I think) and the Idle speed. I was told to take the low speed screw in until I felt slight resistance and back it out 1.75 (I wrote down the exact but don't have the paper with me) I was told to do the same thing with the High Speed and then back it out 1.25. It idled rough so I increased the idle slightly and it seemed fine.

So I put it in the water to berak in the new pistons & rings. It runs great. However, when I get above 24 MPH it starts wobbling and if I go any faster it wobbles even more. It is a 97 GTI. Any ideas?