Spx accidental restoration

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Zenedge

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Hi All,

I’m used to boats, and for the last year, I’ve been looking at jet skis just to get a bit of fun alongside the boat for the kids and myself. I found a cheap old Seadoo SPX (787 engine) which apparently needed a starter motor and throttle cable (yeah, right ).

So I got those jobs completed and took it to the launch ramp to test the engine only to find I needed a carb rebuild. Completed that and returned to the ramp again, fired it up and found that the cylinder jugs are severely cracked and damaged. I now have the engine removed and new jugs, head and head cover ordered but have started a bit of a restoration now.

I have 2 issues that I need a little advice on at the moment (will probably be more as I get further). The ski came with the oil pump removed, I know many on here advocate the pump being fitted and working but I have spent too much time and money on this ‘cheap’ project already, so the premix is here to stay. Question is, what should I do with the oil lines on the block for the rotary valve? The original oil tank has been removed so I can’t connect them the way most folk advise on here. When I got the ski, they were blocked up and tied up high at the side of the hull, is that ok?

Secondly, the water hose that goes to to head via the water regulator valve... there is three T pieces in it... one goes to the water regulator valve and the other two are either side of the WRV tee with a hose connecting them in a D shape sort of bypassing the WRV. Is that normal or should there only be one T piece going directly to the WRV? It looks like it’s been cobbled together badly.

Thanks in advance,

Gordon.
 
Sorry to hear you got the typical craigslist spiel of just needs a starter or battery when it's really a full rebuild...

Hopefully you are checking the crank while its apart and then getting the cylinders bored for new pistons. You also need to be careful to trim the rave valves if you have oversized pistons.

You mentioned a carb rebuild, but one thing to note is that carb kits on these skis have to be OEM mikuni kits. Getting aftermarket kits will cause you all kinds of headaches. You should also ensure the fuel lines are not gray tempo lines or those will need replaces also, along with cleaning the fuel selector.

As for water routing, I'll attach a quick flow diagram below.

Good luck and I'm sure you'll have a ton more questions.


1aec38d31aa4bfb818c36249d49f5642.jpg
 
Zenedge said:
The original oil tank has been removed so I can’t connect them the way most folk advise on here. When I got the ski, they were blocked up and tied up high at the side of the hull, is that ok?
Click to expand...

I'd say no, you need an oil supply for the Rotary Valve gear, someone before you didn't think this through. Just get an oil tank, oil pump and you'll prevent issues later on. The stock oil pumps work fine and are very reliable.

Zenedge said:
Secondly, the water hose that goes to to head via the water regulator valve... there is three T pieces in it... one goes to the water regulator valve and the other two are either side of the WRV tee with a hose connecting them in a D shape sort of bypassing the WRV. Is that normal or should there only be one T piece going directly to the WRV? It looks like it’s been cobbled together badly.
Click to expand...

Not sure what you got going on here, just follow the water routing diagram Ankeneyou posted and you'll be fine.

Zenedge said:
which apparently needed a starter motor
Click to expand...

Used OEM one? or a new aftermarket? typically the aftermarket ones don't last, rebuilding the OEM is usually better option. Ditto above, stick with OEM on the carb kits, the cheap ones can present issues.

You didn't mention it on the rebuild, but I assume you're doing a complete rebuild, not just the top end. I'd tear it down all the way and get a good look at the crankshaft. balance shaft and RV shaft/gear. Depending the hours or wear on it may want to check the RV clearance during reassembly, they can get out of spec and cause issues.

Feel free to ask questions doing the rebuild as you go, but the service manual is good guide to follow.

Final note: If you haven't already or while you're at it, thoroughly inspect the jet pump out and change the oil, make sure the bailers are working fine, inspect the carbon seal, you wouldn't want to sink it first time out after a nice engine rebuild.
 
Thanks ankeneyou for that diagram. I thought mine didn’t look right, I’ll tidy it up on rebuild.

I know you’re correct Gordon, I had intended on doing a top end rebuild but I’ve come this far so I need to keep on going and do the crankcase too. The problem is, I started to remove the RV cover and mag cover and the bolts were ready to sear, I just didn’t want the headache of drilling them out but I know I need to do it.

The starter I bought right away as I thought that was all the ski needed, so that was new aftermarket but I still have the original one so will rebuild that and keep it as a spare if the new one fails.

The carb rebuild kit I bought a cheap amazon kit, then read all the horror stories and binned it and fitted Mikuni. There will be a very good reason that the cheap stuff is 1/10th of the price of Mikuni lol.

The carbon seal, is that a part I should be replacing anyway or should I only replace if it needs it? How do I check it???

Thanks a lot for your advice.
 
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Thanks for the advice, unfortunately I’m in the uk and getting parts and advice here is pretty difficult. I’ll have a look at the carbon seal and see how it looks.
 
Zenedge said:
The carbon seal, is that a part I should be replacing anyway or should I only replace if it needs it? How do I check it???
Click to expand...

Check to see if it's using the oring or c clip to hold the SS hat, the oring can fail, at some point in the late 90's Seadoo switched to the c clip. Check to see if it's in good shape, not pitted bad and is evenly receiving pressure.
 
If the mating surface isnt perfect, so can put some high grit sandpaper on a flat surface and use that to clean up the carbon seal. The real important part is the boot/bellows. You need to make sure it's not hard or has any holes. It puts pressure on the carbon seal against the stainless hat and keeps you from sinking. Thsts another area after market is junk, they are all too hard.
 
For the oil lines some people use a radiator flush tee with the garden hose cap, others use an eBay motorcycle brake master cylinder. Either way you need some kind of reservoir and way to keep those hoses full of API-TC rated oil.
 
mikidymac said:
For the oil lines some people use a radiator flush tee with the garden hose cap, others use an eBay motorcycle brake master cylinder. Either way you need some kind of reservoir and way to keep those hoses full of API-TC rated oil.
Click to expand...

Are you saying I can use a brake fluid reservoir with a tee under it leading to both oil inlets???

I thought they were a flow and return on the crankcase, so I’ve been looking for an oil tank with an outlet at the bottom and a return inlet at the top of the tank (haven’t found one after hours of searching).
 
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Yes you can tee them to keep air out of the system.

There is no flow, it’s just a flooded sump. As the inner crank seals age they can seep oil depleting the oil in the chamber so it is something you need to keep an eye on since you don’t have the big OEM tank.
 
Hey folks, as I said earlier, I’m now doing a full rebuild and stripping painting parts as I go. I’m now on to exhaust parts, obviously the exhaust manifold that bolts directly onto the jugs will need painted in heat resistant paint but what about the rest? The pipe that comes in 2 parts, does that get hot enough to need high temp paint or will regular rattle can paint be ok on that? I plan to use a bare metal ‘direct to rust’ type paint (even though the parts are stripped, with no rust present) as I have found a good paint which has a really nice finish and good filling qualities. It almost looks like powder coating but not too thick and the colour is perfect for my engine bay.

Thanks, Gordon.
 
Be careful with the direct to rust paints as some of them don't cure correctly if they are not applied to rust and since your engine is aluminum and can't rust it could be an issue.

Any good engine paint is fine. I used to use the Valspar rattlecan from Lowes with their clear on all my engines because it was an exact match for the Seadoo white and purple but they stopped making it.
 
Ah, ok, I didn’t know that... will check the details before I go painting. I’ve spent too much time stripping paint to mess it up with a bad job. Thanks for the warning.
 
I checked the paint and it’s ok on aluminium

Another question which I think I’ve already answered but want to double check anyway... I assumed that this manifold would need high temp paint, is that correct? The regular temp metal paint would be a better colour option if I can get away with it, but not a big deal either way.
 

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Zenedge said:
I checked the paint and it’s ok on aluminium

Another question which I think I’ve already answered but want to double check anyway... I assumed that this manifold would need high temp paint, is that correct? The regular temp metal paint would be a better colour option if I can get away with it, but not a big deal either way.
Click to expand...
wet exhuast
 
Awesome, that means I can keep the whole engine scheme the way I want it. It is looking pretty good, even if I do say so myself lol

Thanks for the reply noviceskier
 
mikidymac said:
Any good engine paint is fine. I used to use the Valspar rattlecan from Lowes with their clear on all my engines because it was an exact match for the Seadoo white and purple but they stopped making it.
Click to expand...

Not to derail, but I ordered 3 cases of 6ea purple online for like 2.50 a can.. you can still get it, just not through Lowes.
The white, rust oleum canvas white is an absolute dead on match.
 
Zenedge said:
I checked the paint and it’s ok on aluminium

Another question which I think I’ve already answered but want to double check anyway... I assumed that this manifold would need high temp paint, is that correct? The regular temp metal paint would be a better colour option if I can get away with it, but not a big deal either way.
Click to expand...
None of it gets hot enough to warrant high temp paint. If it's too hot for you to comfortably keep your hand on, after running for hours on end, then you've got a problem with your ski.
 
DanSquires said:
Not to derail, but I ordered 3 cases of 6ea purple online for like 2.50 a can.. you can still get it, just not through Lowes.
The white, rust oleum canvas white is an absolute dead on match.
Click to expand...
Any chance you could provide link to where you found that? Would be nice to use for later projects.
 
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Just make sure you clear it with gloss. It doesn’t look the same in the satin out of the can.
 
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