Help please tried every thing almost

[1stdoo]

Hi every one I hope some one can help me out. With my 1996 seadoo speedster

One of my engines seem to be stuttering missing when revved and and now and then back fired rarely but it does and will not go beyond 6000 rpm in the water and 7000 out of the water.

The problem started when I slowed down and a back fire was heard, then I could not get it to rev past 4000 rpm when not moving but if I wound out the other motor to 7000 the bad motor would go up to 6000 , in the water when moving.

• Nether plug is fowled, both look the same.
• Temperature on both exhaust ports seems the same
• Compression both at 145.
• Switched carburetor from good engine to bad no change.
• Checked inline fuel filers both clean.
• Switched the motor electronics from one motor to the other as in reconnected the computer from the good motor to the bad and no change made sure I switched everything.
• Had both batteries load tested they are fine.
• I recently rebuilt both jet pumps, I checked it and it spins freely.
• Took jet pump off no change.
• Switched fuel lines from good motor and rooted to bad, no change.
• Checked the fly wheel seems fine.
• The stator adjustment bolt are tight.
• Checked all bolts on the engine everything is tight.

I have exhausted most things other than rotary valve and crank seals but the motor was rebuilt buy Buy the previous owner last year at, an authorized seadoo dealer

I am thinking it is the stator now but would like to get your thoughts.

Thank you your input would be great.

 

[Dr Honda]

Welll......

It sounds like the rotary valve has gotten out of time, or the clearance is very high in the rotary valve housing.

Unless the gears gave up... it's not a common thing to happen... and unless it was run low on oil, the clearance shouldn't have opened up. But it's something to check.

The second thing... I know you say the the stator bolts are tight... but did you verify the timing?

Because of the design of the engine... it's dam near impossible to get a back fire, unless something is very wrong.


Last thing. I would still clean the carbs on the engine that back fired. When that happens... the heat, and pressure can really mess up the carbs.

 

[seadooya]

you try new plugs? Hows the exhaust tube, from muffler to outlet? Can it crush as easy as the other?

 

[1stdoo]

I am going to pull the engine tonight and pull the fly wheel. Not sure how the stator would have come out of timing maybe it was never set right in the beginning, and has now become more pronounced. From what I can see on the STB web site they say there are marks on the stator and the case and just line them up? The manual does not mention this. What are you thoughts?

As for the rotary valve I am going to look at it also I was going to check the seals, around it. Before I took the boat out this year I checked to make sure the oil was running threw the engine and looked at the large hose at the bottom of the motor and it was full of oil, but you never know.

I have not had a back fire since I put on the carbs from the good engine.

Thank you for you thoughts.

 

[1stdoo]

Yes I tried new plugs and checked the pipes. Everything seems to be good from what I can tell. Could a internal water leak from the exhaust manifold to the header cause this?

But this probably is not the problem as it runs the same with the water on or off.

I can not see any leaks in the exhaust, I did have a water leak at one of the plug welds last year I just fixed it with muffler putty as a short term fix but it seems to be working well no leaks at all



Thank you for you input

 

[seadooya]

to align the stator, make sure the "slots", where the 3-allen bolts are, are centered in the slots. Other than that, cnt be wrong.

 

[1stdoo]

I discovered a small leak. I noticed there are 2 pulse line nipples on the block and one has a cap there is a hole in the cap not a very large hole. When I blow threw the cap I can find the leak. Could this be causing my problem, it is a very small hole but a hole.

Thanks

 

[seadooya]

defintly, your losing pressure.

 

[1stdoo]

I am hoping this is the problem. I will try and start it tomorrow as I descovered it at 10 pm I live down town toronto probably would not be a popular thing to start it now.

I will let you guys know how it goes

 

[1stdoo]

Found the problem

In the end it was a bad stator. It checked out fine with an ohm meter but when I swapped it with one I knew worked everything was back to normal.