Seadoo speedster jet boat

[Water sports]

With the top of the motor replacing the O-rings will this for loosen the head thanks heaps this is a big help

 

[mikidymac]

The head is two pieces, the head and the shell and both are held on with the same bolts you see at the top of the engine so you should replace all o-rings when removing them.

 

[Water sports]

Okay sorry if I’m a bit dumb on this but wouldn’t I have to replace the head gasket as well if I took off the top cover if this is the same bolting, I was just wanting to remove it to see if anything was blocked with corrosion or do you think it’s best left alone

 

[Water sports]

And just one other question I am actually in New Zealand is there anywhere you could recommend either in New Zealand or America to get the carburettor jets 67.5

 

[mikidymac]

Any motorcycle shop should be able to get them for you as they are a common Mikuni part.

There is no actual head "gasket" it is just more o-rings.

 

[Water sports]

Great thanks so much I will call A motorcycle shop

just another question, you know the carburettor adjustment screws I need to remove these to clean out the carburettor correctly do you know the amount of tunes they should sit at or the amount of turns out it appears one is fully screwed in I don’t want to get this wrong

 

[mikidymac]

First follow this thread....Carb Rebuild Thread

Your boat should be the same as a 1999 SPX and has the same jetting as the SPX so I am gong to say..
Low Screw 1-1/2 turn out from all the way in.
High is closed.

 

[Water sports]

Hi guys, trying to determine how to fix the leftside engine, which seems to be filling up with oil, how can I fix this.

 

[mikidymac]

If it’s filling the cylinders it’s typically the inner crank seals. The only permanent fix is a remanufactured crankshaft.

 

[Water sports]

Oh goodness really this only seems to happen when it is sitting for a period of time I’m just wondering if the oil is running down the piping of the oil reservoir and dripping through the seal of pump someone mentioned it could be the block seal of the pump which I’m not quite sure what that is I’m really hoping it’s not the crank seal as there is major

 

[Water sports]

These motors are 2 Stroke a ?

 

[Water sports]

Sorry for all the questions but this is a huge help if you could just be with me,
I am just crossed checking the carburettor jetting the 1999 Seadoo SpeedStar787 twin engine 2 stroke.

main mag jets ?
PTO jets. ?
Pilot jets ?

 

[mikidymac]

Yes it’s a 2-stroke.
No oil pump won’t flood the engine. From your symptoms it’s the inner crank seals that leek from the rotary cavity and the only permanent fix is to replace the crankshaft.
A temporary fix is to put a shutoff valve on the 12mm oil lines from the tank to the intake side of the crankcase.

There’s no PTO jet.

Front (MAG) carb
Main 140
Pilot 67.5
High speed screw 0
Low speed screw 1-1/2

Rear (PTO) Carb
Main 142.5
Pilot 67.5
HS screw 0
LS Screw 1-1/2.

 

[Water sports]

Thanks for this information so putting a shut off valve is this like a tap that will shut off the wheel running down to the motors and I would have to turn this on before using the boat
.
The carb is currently running 145 which I thought these were in both back and front carbs I will need to check as the main jet do you think I should change this to 140 ? I am having not a lot of luck obtaining the 67.5 jets I went to a motorbike shop and they said to me they wanted the model of the carburettor I did tell them it was a Mikuni, but that didn’t seem to be enough for them they had some 67.5 jets on the bench waiting for me, but these were too big to fit into my carb

 

[Water sports]

Hi can you tell me what this lower pipe is it sits under where the carbs sit, as it does appear to be quite soft, should I replace it.

 

[Water sports]

Also next question, how to pull out the blades and service this area.

 

[Water sports]

I removed the cap and spring, but found A little difficult to pull off the other cap sitting over the blade, however this did con off but the blade does not seem to want to pull out.

 

[Water sports]

Sorry another question do you think I should remove the cap on the engine, very top plate where the water comes out to check if this is corroded you did mention I would have to replace the O-rings, just really only want to check that part under where the water outlet sits however when I removed the pipes these appear to be quite clean I am replacing all water pipes on boat engines.

 

[mikidymac]

Hi can you tell me what this lower pipe is it sits under where the carbs sit, as it does appear to be quite soft, should I replace it.

That hose should be soft and they don’t go bad.

That’s the hose you put the shutoff valve on but you have to remember to always turn it on. Some people put the lanyard on it so they don’t forget.

 

[mikidymac]

I removed the cap and spring, but found A little difficult to pull off the other cap sitting over the blade, however this did con off but the blade does not seem to want to pull out.

You have to unscrew the inner black plastic top and remove it unhooking it from the rubber bellow.
Then you have to remove the two Allan bolts and remove the blade and housings together.

You need a new housing gasket and inner shaft o-ring.

 

[mikidymac]

Sorry another question do you think I should remove the cap on the engine, very top plate where the water comes out to check if this is corroded you did mention I would have to replace the O-rings, just really only want to check that part under where the water outlet sits however when I removed the pipes these appear to be quite clean I am replacing all water pipes on boat engines.

No, there’s no reason to do that.

 

[Water sports]

O right got you, what is a lanyard, how does this work

 

[Water sports]

Seadoo 787 jet boat just Trying to determine what water pipe would I block off if I had to be toed toed.

 

[mikidymac]

Lanyard is the kill switch that lets you start the engine.

The hose that comes from the back then tee’s to a little hose on the muffler then goes to the head. There’s actually an arrow cast into the head where the hose connects showing flow into the engine. You pinch this hose between the back of the ski and the tee to the muffler.

 

[Water sports]

Yes it’s a 2-stroke.
No oil pump won’t flood the engine. From your symptoms it’s the inner crank seals that leek from the rotary cavity and the only permanent fix is to replace the crankshaft.
A temporary fix is to put a shutoff valve on the 12mm oil lines from the tank to the intake side of the crankcase.

There’s no PTO jet.

Front (MAG) carb
Main 140
Pilot 67.5
High speed screw 0
Low speed screw 1-1/2

Rear (PTO) Carb
Main 142.5
Pilot 67.5
HS screw 0
LS Screw 1-1/2.

Yes it’s a 2-stroke.
No oil pump won’t flood the engine. From your symptoms it’s the inner crank seals that leek from the rotary cavity and the only permanent fix is to replace the crankshaft.
A temporary fix is to put a shutoff valve on the 12mm oil lines from the tank to the intake side of the crankcase.

There’s no PTO jet.

Front (MAG) carb
Main 140
Pilot 67.5
High speed screw 0
Low speed screw 1-1/2

Rear (PTO) Carb
Main 142.5
Pilot 67.5
HS screw 0
LS Screw 1-1/2.