Here we go again… Seadoo bogging down in water

[TurnerBFC]

Let me start with a video link:

Long story short; revs great on trailer - bogs in the water. I can ‘feather’ it to rev up and go on plane sometimes but mostly it’s no good and just bogs down like the video shows.

- all new fuel lines, grey is gone
- tested with a known and working OEM rectifier
- carbs just done with Mikuni kits (not my first time doing them)
- pop off average 39psi each
- 10psi leak test held for 5 minutes no problem
- jets replaced at time of carb rebuild to be safe
- fuel filter replaced with inline one (tested with and without, no change)
- plugs swapped - no change


Where should I look gents?

 

[lavasioux]

Hi,

Have you checked the compression? If so what did you find?

What is the history/ did you just get it? Have you had it, was it running fine one day, not the next?

 

[TurnerBFC]

Not yet - that’s next on my list. I only have a cheap tester and I don’t trust it.

I bought it in the winter. Never knew how it ran before

 

[burtshaver2021]

Nothing wrong with cheap compression testers, however if it’s one from harbour freight be careful as they are notorious for reading 90 pounds maximum. Mine is from Canadian tire, cheap but I trust it.

 

[TurnerBFC]

Mag is 120psi and PTO is 119psi.

Thoughts on that?

 

[burtshaver2021]

Mag is 120psi and PTO is 119psi.

Thoughts on that?

Time for a rebuild, should start no problem on the trailer but probably not when under load in the water

 

[TurnerBFC]

Looks like pistons are 1.00 over already.

Does that require new sleeves?

 

[mikidymac]

Looks like pistons are 1.00 over already.

Does that require new sleeves?

Yes or just find a set of clean used jugs and have those bored.

This wouldn't happen to be a SBT rebuild would it?

 

[TurnerBFC]

Yes or just find a set of clean used jugs and have those bored.

This wouldn't happen to be a SBT rebuild would it?

Nope ! It’s oem

 

[Venturian1]

Compression test. Is there an API standard method? My father was top mechanic for the County Fire Dept, and said
( now this was a car) First take out all plugs, make sure the O-ring on the threads is good, snug it by hand firmly, place the gauge so you can see it while cranking the engine over and watch the pointer go up once, twice, and after the third, stop cranking and record pressure. But the car was 4-stroke.
Before I got into jet skis I had a few boats, and got fairly good with the 2-stroke Mercury outboards. I found out the testing compression procedure was not the same as I was taught, and I liked this new method, it produced much higher numbers! just crank until the pointer stops going up and that's the number to record.
Somewhere I read a procedure for 2-stroke Seadoo is same as the Mercury method, but you also have both plugs out of the head, wires back on, and plug grounded, or, wires put on provided grounding post to protect the IG module/mpem, fully charge your battery, and hold the throttle wide open while cranking it over. Ignition grounded in all methods.
So is it not important exactly HOW the compression test is performed?
The Sea-Doo method seems aimed at fastest cranking speed, and less vacuum generated for higher numbers. Seems like cheating to me!
Hell, why not add a few squirts of 85-140w to give the rings some help?
There should be a specific RPM for doing this,