1997 Seadoo XP 787 Stalling / Dying

[DeFreitas Enterprises]

Well, we don't need to telly you to stop using that oil and use the correct one.

I'm turning into a believer on not using the cheapo oil. The difficulty is there are so many both conflicting advice in the mechanic / mechanical world, and also "wives tale" things that get passed along as fact but really are either things of the past or no longer applicable. Weeding out the misinformation and establishing a view point for oneself, while avoiding being ignorant and messing things up is a lifelong journey.

Are you still supplying oil to the rotary gear sump?

Not sure what this rotary gear sump is that you refer to. One of the first things I did after purchasing was rigorously read the shop manual, since I have never owned a PWC. I'm pretty experienced with 2 and 4 strokes and wrenching various machinery but like I said never owned a boat.

What I found for lubrication was that there is a counterbalance shaft which sits in a small amount (I believe 30 mL off memory but don't quote me) of motor oil. Also the impeller has an oil housing as well. But those were the only two I found in the manual, and like the general tune up I was putting that off until the end of the season. It might be stupid, but with 10+ motorcycles, countless equipment for work, and being slammed with solar clients I just can't find time to wrench on the ski now, when all was well and good. I may regret that later, but it is a decision I am rolling with. I'll have to lookup the rotary gear sump.

Dumping oil into the gas tank is not the way you do pre-mix, you could end up sucking up oil off the bottom of the tank.

hahaha I know I know. My method of choice is a few gallons at a time, but this fill up I had half a tank left already, so I was lazy and figured I could dump the whole oil in on top of the other 5 gallons, and with the splashing of the fill up, and driving 5+ miles to the boat ramp, I figured it would all get mixed anyways. If I am low on fuel in the tank, or especially if I am filling a tank from dry, I definitely wouldn't put all the oil then fill with gas. I'm trying to be honest here but yeah I got a bit lazy on that half fill up.

I can't see your pictures but you could be fouling plugs.

You may have to sign in to a google account to see since I upload them to google drive, and post the shared link. It seems to work for another member so it may be on your end. I like doing it this way since the images don't clog up the thread. Makes for an easier read and you can open pics you want and skip others. Forums are my life saver for the motorcycles, and even work / electrical questions. I am always amazed at the community of passionate, extremely knowledgeable people who spend their valuable time helping others. Humans are freaking awesome. Well some of us anyways

I would be a little concerned with the 10 psi difference in compression between the cylinders.

I'm going to elaborate more on my question with this in the quote below from the next poster.

First, your spark plugs look like hell. Get some new ones ASAP. On these old skis, you should replace them every year and even twice if you use your ski a lot. With rust like that around the base of the plug, I wonder how old they are.

Yeah I should have ordered new ones right after purchasing. I just got a set of 4 today and swapped them after doing the compression test. 2 new ones in, and 2 spares ready to go if I foul them again (if that is what was happening).

Second, as for compression, I would try another tester just to make sure but 10 PSI diff as @mikidymac said is definitely a bit of concern (I've been through that and it cost me an engine). I bought a cheap tester a couple years ago that was not accurate and I thought my engine was toast. I retested it with an expensive one and everything was OK A1. Don't know about your tester since I am not a mechanics (but I am learning).

Okay here goes ha! So do you truly mean I should be concerned or is it that I should be observing and regularly checking? Concerned is a pretty strong word in the mechanical world. It is usually the precursor to preventative maintenance, which in this case would be ripping apart the jug. When I'm still at 130 psi, and "only" a 10 psi difference, would this really be what I should be doing? If I test it in a couple months and I'm down another 10 psi then I would take action then, but I don't think it is necessary yet...?

Furthermore, I may be mistaken, but what can really go wrong with letting a compression discrepancy linger? Eventually it should get worse, and I'll notice a loss in power / performance and then address at that time. Is there something catastrophic that can happen from a compression discrepancy? Can you elaborate on how you lost an engine due to this?

Third, as for the DESS post, yes, the issue could be intermittent at first but usually it gets worse within a matter of days (after a week, mine became completely unusable). Also, check the inside of your key for the presence metal flakes (clinker?).

No metal flakes, but the inside of the key just looks to be in rough shape, I posted some pictures in a previous post but here is another link.

20190705_101844.jpg

Yeah the DESS post has me concerned. If I fouled the plugs then I don't think she would start back up 30 seconds later, and I was having the issue where I needed to unplug and replug the key before the starter would crank when it did die. Someone posted on another thread indicating that is a tell tale sign the DESS is starting to go. I think I am going to take her back to the river, and go upriver but not far, then do some circular riding and see how it goes. If she dies on me I can float down and paddle to shore. Last time I was so far away it was a total debacle getting back to the other boat ramp (thanks for uber / lyft).

Fourth, drop this cheap oil, there is no savings in trying to save a few bucks for oil. Some people will also tell you to empty the oil tank before putting the good one and not mix them.

Well there is a savings, but as you and others have mentioned it does not outweigh the potential maintenance and repair work. I am a believer now though, due to apparently mostly the RAVE valves.

 

[mikidymac]

I'm turning into a believer on not using the cheapo oil. The difficulty is there are so many both conflicting advice in the mechanic / mechanical world, and also "wives tale" things that get passed along as fact but really are either things of the past or no longer applicable. Weeding out the misinformation and establishing a view point for oneself, while avoiding being ignorant and messing things up is a lifelong journey.

This is not an old wives tale. The seadoo engines run hotter and have more performance than an outboard engine so they require a different oil. Not a TCW-3 oil but a higher rated API-TC oil. There is a reason Seadoo specified this higher spec oil. We have seen piston seizures, stuck rave valves and well as leaking crank seals from running the wrong TCW-3 oil.

Not sure what this rotary gear sump is that you refer to. One of the first things I did after purchasing was rigorously read the shop manual, since I have never owned a PWC. I'm pretty experienced with 2 and 4 strokes and wrenching various machinery but like I said never owned a boat.

Your engine uses a rotary valve on the intake instead of reeds. This rotary valve is driven 90 degrees off of the crank and has a sump full of oil to lubricate the angle drive. This sump has to be constantly supplied with API-TC 2-stroke oil. Form the factory there are two 12mm lines that feed oil directly from the oil tank to the sump.

What I found for lubrication was that there is a counterbalance shaft which sits in a small amount (I believe 30 mL off memory but don't quote me) of motor oil. Also the impeller has an oil housing as well. But those were the only two I found in the manual, and like the general tune up I was putting that off until the end of the season. It might be stupid, but with 10+ motorcycles, countless equipment for work, and being slammed with solar clients I just can't find time to wrench on the ski now, when all was well and good. I may regret that later, but it is a decision I am rolling with. I'll have to lookup the rotary gear sump.



hahaha I know I know. My method of choice is a few gallons at a time, but this fill up I had half a tank left already, so I was lazy and figured I could dump the whole oil in on top of the other 5 gallons, and with the splashing of the fill up, and driving 5+ miles to the boat ramp, I figured it would all get mixed anyways. If I am low on fuel in the tank, or especially if I am filling a tank from dry, I definitely wouldn't put all the oil then fill with gas. I'm trying to be honest here but yeah I got a bit lazy on that half fill up.



You may have to sign in to a google account to see since I upload them to google drive, and post the shared link. It seems to work for another member so it may be on your end. I like doing it this way since the images don't clog up the thread. Makes for an easier read and you can open pics you want and skip others. Forums are my life saver for the motorcycles, and even work / electrical questions. I am always amazed at the community of passionate, extremely knowledgeable people who spend their valuable time helping others. Humans are freaking awesome. Well some of us anyways

If you use TapaTalk on your phone you can upload photos directly and easily.

I'm going to elaborate more on my question with this in the quote below from the next poster.



Yeah I should have ordered new ones right after purchasing. I just got a set of 4 today and swapped them after doing the compression test. 2 new ones in, and 2 spares ready to go if I foul them again (if that is what was happening).



Okay here goes ha! So do you truly mean I should be concerned or is it that I should be observing and regularly checking? Concerned is a pretty strong word in the mechanical world. It is usually the precursor to preventative maintenance, which in this case would be ripping apart the jug. When I'm still at 130 psi, and "only" a 10 psi difference, would this really be what I should be doing? If I test it in a couple months and I'm down another 10 psi then I would take action then, but I don't think it is necessary yet...?

Furthermore, I may be mistaken, but what can really go wrong with letting a compression discrepancy linger? Eventually it should get worse, and I'll notice a loss in power / performance and then address at that time. Is there something catastrophic that can happen from a compression discrepancy? Can you elaborate on how you lost an engine due to this?

On your engine 150 psi is perfect compression and at 120 psi you are due for a rebuild and it might not start in the water. With a 10 psi difference between cylinders something is happening to the lower cylinder. It could be more worn or starting to scuff and seize. If it was mine I would check it after each ride and see if it is getting worse. A dirty carb could be running one cylinder lean and starting to scuff the piston.

No metal flakes, but the inside of the key just looks to be in rough shape, I posted some pictures in a previous post but here is another link.

20190705_101844.jpg

Yeah the DESS post has me concerned. If I fouled the plugs then I don't think she would start back up 30 seconds later, and I was having the issue where I needed to unplug and replug the key before the starter would crank when it did die. Someone posted on another thread indicating that is a tell tale sign the DESS is starting to go. I think I am going to take her back to the river, and go upriver but not far, then do some circular riding and see how it goes. If she dies on me I can float down and paddle to shore. Last time I was so far away it was a total debacle getting back to the other boat ramp (thanks for uber / lyft).



Well there is a savings, but as you and others have mentioned it does not outweigh the potential maintenance and repair work. I am a believer now though, due to apparently mostly the RAVE valves.

 

[DeFreitas Enterprises]

tagging you Miki

I am going to embark on the carb rebuild, and have reread your excellent thread on it again. Is the proper Mikuni rebuild kit the one you mentioned, Mikuni 12-1458?

Found a set for rebuilding two carbs here for $137:
SeaDoo Dual Genuine Mikuni Carb Rebuild Kit & Needle Seat & Base Gasket GTX 94

But single rebuilds can be had on eBay for $42, so I'd save like $55 total
MIKUNI Super Bn Rebuild Kit Mk-Bn38/44 Spr Carb Rebuild Kit MKBN3844SPR 12-1458 | eBay

 

[mikidymac]

The one from jet ski plus looks to be correct.
The one from Ebay I am not sure it’s genuine or not.

You will need the base gaskets.

The other thing is neither of them come with the correct springs so if yours aren’t correct you need that too.

Although not the best deal OSD Seafoo does sell everything genuine for one stop shopping.

The 1997 XP DOES NOT use the black 80 gram springs and does have accelerator pumps.

It also uses a different ON/OFF valve and I think 5/16” fuel lines with the return being the only 1/4”.

 

[DeFreitas Enterprises]

Thanks Miki. Yesterday I did the carb rebuild. I didn't take pictures but everything inside was very clean. Main and pilot jets not clogged at all, fuel filter clean as well. I did notice some of the parts were not genuine Mikuni. The fuel check valves didn't seem like it, but maybe the blue marks were just dissolved away. The diaphragm definitely wasn't, no red mark on the dimple.

I swapped in new rubber gaskets and the Mikuni diaphragms, and checked the pop off pressure. The carb with the fuel pump popped at 30 psi, the other one popped at 40 psi. I swapped in one of the springs in the Mikuni kit to the 40 psi carb and it popped at 30 psi. Seems a bit low, but following your spec of 28-40 psi I'm satisfied with them both at 30 psi.

Since the schrader valve on the pop off gauge was not completely leak proof, I did not check to make sure the carbs held pressure, but with OEM diaphragms I'm pretty confident it would pass.

So the good news is the carb rebuild went pretty smooth. The only hard part was replacing the fuel check valves and getting the black rubber holder reinstalled without breaking it or the check valve. The bad news is that since the carbs looked to be in great shape I do not think they are the source of the bike stalling out.

Next steps are going to be cleaning and inspecting the RAVE valves, since apparently by use of outboard oil could cause problems there. I'll also retest the compression on the cylinders to see if it got any worse.

-Alex

 

[mikidymac]

You can't use two different springs in the carbs. They both have to be the correct and same springs, you can't mix and match to make pop-off the same.

 

[DeFreitas Enterprises]

You can't use two different springs in the carbs. They both have to be the correct and same springs, you can't mix and match to make pop-off the same.

I guess I am missing the point in the pop off pressure then. I'm going to roll with it and see how the ski does. I do have some good updates and requesting some more advice with the RAVE valves.

So since the carbs checked out great, I was still searching for the cause of the ski stalling & cutting off power at WOT. It also started doing something extremely strange on the very last ride of last season. At 1/2 throttle or less it was fine, but when I went WOT the ski revved up accordingly but didn't go anywhere. It was almost as if the impeller wasn't rotating or the shaft got disconnected. I don't know why else this would happen, so it is kind of concerning, but I am going to focus on the original issue of the ski stalling and losing power at WOT.

With the carbs cleaned and no issues seen from TC-W3 oil, I checked compression again. 145 psi on one cylinder and 135 psi on the other. No issues with compression. I remembered some one advised that TC-W3 oil can do some damage to the RAVE valves, so I decided to open those and inspect. What I found was pretty much a total hackjob.

The valve towards the impeller of the sled I did first since it comes out easier.

Valve: 20200407_160708.jpg
Some carbon buildup, will need to clean.

I noticed the green bellow, must be an aftermarket rebuild kit.
No spring / retainer for the bottom of the bellow, held on my zip tie. Normal? I'm guessing not.
20200407_161416.jpg

Not sure exactly how to judge condition? Any advice appreciated.


Now to the other RAVE valve. Here is where the fun begins.

Underside of cap:
20200407_161734.jpg

Strange bolt and washer on top of bellow:
20200407_162228.jpg

Strange nut and washer underneath bellow:
20200407_162532.jpg

Now I see why they did this, even if it is a hackjob. The threads on the valve were stripped:
20200407_162545.jpg

Another zip tie on bottom of bellow. Normal or no?
20200407_162659.jpg


Comparing two manifolds. Why is the shape of this recess different? It almost looks like one is broken.
20200407_163522.jpg

Once cleaned up a bit with gasoline it is even easier to see. What's going on here?
20200407_164023.jpg


Moving Forward:

So I am leaning this route currently. I found a full rebuild kit on eBay which has the valve I need to replace the stripped one, and the other parts for the rebuild as well.

eBay Valve Rebuild

It doesn't have the manifold though, so I need to know whether the two I have are normal. Should they look different in that area? I can't see why they would. If not, I'll have to find one on ebay.

Thanks for all your help. Excited to get this back on the river and see if she is all fixed.

-Alex

 

[mikidymac]

First as I said you can’t use 2 different springs and it is shutting off because it’s starving for fuel.

Compression is not good as one cylinder is 10 psi lower and at 135 psi you have something bad starting like seizing a piston from running lean and shutting off.

 

[mikidymac]

Yes, total hack job on the RAVES. Green bellows are correct, there shouldn’t be any spring on the bottom bellows and housings shouldn’t be different.

Some of the cheap aftermarket kits and bellows are too stiff and won’t actuate correctly.

And no, you should never be using TCW-3 oil in a Seadoo ever.

 

[JeremyD615]

One of those rave housings is aftermarket, which is why the recess is shaped differently. With the condition of the raves and the plugs, I’d say that ski has lived a pretty rough life. With the combination of your shutdown issues, the uneven compression, and the general condition of your wear items, I’d say Miki’s hit the nail on the head with the lean seizure... Go back over your fuel system with a fine toothed comb, but I have a feeling you’re going to be looking at a rebuild at some point in the not too distant future.