98 Speedster engine tapping (valve tapping sound)

[jamin690]

Hey all,

Well after a lovely july fourth weekend of boating, we may have done some damage to our Speedster. There is now a kind of major valve tapping sound coming from the right engine. Between having some cheaper oil in it and really running the heck out it I beleive we blew a bearing on one of the pistons. So I am planning on rebuilding the top end this week (hopefully there lies the damage). I notice that there are different bore pistons and also different width cylinder base gaskets and I need some assitance identifying which ones I need so I can get these parts ordered.

Engine type: 787
Serial: M5078248

Any help is greatly appreciated.

 

[kustomkarl]

Welcome to the seadoo forum jamin690. It sounds like it might be a bearing knock you have. I would tear the engine down and check before you just replace the top end. If the crank bearings are bad, you might want to remove the engine and install a re manufactured engine. It could be cheaper in the long run. Click on the "parts" link at the top of the page for any parts you might need. If in doubt of the size pistons and rings you need, if you go in that direction, you will need to either look for STD on the piston or use a micrometer to measure it when it is apart.
Do you have a seadoo shop manual? If not here’s an idea for you. You could join as a "premium member". As a premium member you can down load a authentic seadoo manual from the seadoo manual library. In the library is a variety of manuals for almost all years and models. You can view as many as you like on line as a PDF file, or download it and print it for your personal and private use. There are operator manuals and repair manuals for you to do your own repairs on your seadoo. The repair manuals have everything from troubleshooting, repair procedures to winterizing. It contains wire diagrams torque specs and pictures for disassemble and assemble instructions. In the spec sheets it tells everything needed to maintain oil changes, spark plug gaps, carburetor rebuilds and impeller wear ring tolerances. Click on the "Seadoo Manuals" link at the top of the page for more details. If you need any help or get in a jam, we are always here to answer your questions too. Premium members get priority when it comes to getting quick detailed answers.


Karl

 

[jamin690]

Thanks Karl,

Always good to know there are pro's around here to help. I do have the shope manual and have looked at the subject parts in detail. I am in the process now of ripping the motor down and the biggest problem I see right now is that the only parts in this matter come straight from seadoo which only has 2 options of shipping, overnight and ground! I took the suggestion from you and my local seadoo shop and I am opening it up before I order parts. I may need the repair manual before I put it back together which I will do if needed (torque ratio's and such). I have one question though, when I removed a bolt from the exhaust manifold, I heard water entering or leaving (my neighbors kawasaki waverunner sunk the day after he removed the exaust manifold) So I took it out of the water. Are there water locks (air tight) sealed within the exauhst that keep water out? It would be good knowledge to know that I wasn't going to sink my boat by having an engine dismanteled.