1996 Seadoo GTX 787 losing a cylinder? Cant find pressure leak!

[Travisgg]

Hey boys will be doing pressure test potentially this weekend. Been doing tons of searching and youtubing still have a couple questions on the pressure test. I get the idea of blocking the intake (carb holes) and the exhaust holes, and assume use the carb pulse line to pressurize.... question is what other lines need to be blocked? Oil lines? water lines off cylinders ? Raves stay in place or need blocked?

Thanks!

 

[burtshaver2021]

No nothing else to block, when I did the leak down test on a 717 I used an old inner tube and sandwiched it in between the carbs and block, took the exhaust off from the manifold and sandwiched it there. The 717 doesn’t have rave valves but I do believe you need to block those as well, I would think you could take them out, take the gillotine ( can’t spell it) out and use the housing to sandwhich the tube there. You could also pressure test the rotary valve cavity, just pressurize where the oil line goes to it and block off the return which was at the back of the 717, could be a vent nipple, not sure. I don’t think you have to but I did block my cooling line nipples when testing the outer seals but pretty sure you don’t have to.

 

[burtshaver2021]

What kind of set up do you have for pressurizing?

 

[Travisgg]

What kind of set up do you have for pressurizing?

Was going to use my pop off tester tool? Has gauge and schrader valve...

 

[burtshaver2021]

That will work fine

 

[burtshaver2021]

Most will say to pump 8 pounds in but my manual said 6 pounds so I went with the 6. Just worried about damaging a seal

 

[mikidymac]

8 psi has always been the standard I use for pressure testing.
Correct, only have to block off the carb inlet and exhaust outlet, nothing else. Pulse fitting is your pressure test port.

 

[Travisgg]

Anyone have an issue with a color of that wrist pin bearing? My old one was more of a darker aluminum just like the pin. That's the kimpex part number in the second picture. Just haven't seen bright shiny silver ones before...

 

[burtshaver2021]

My self I’m not familiar with Kimpex, you’ve done this before? No need to mention little things like 2 stroke oil on the caged bearings, on pistons and walls etc. during assembly?

 

[Travisgg]

My self I’m not familiar with Kimpex, you’ve done this before? No need to mention little things like 2 stroke oil on the caged bearings, on pistons and walls etc. during assembly?

Yeah built a few 2 stroke motors just such a weird color on this bearing... Makes me nervous when you see a different color of metal is why I was wondering. Maybe this is the latest greatest or something? And yes... Lube lube lube !!!

 

[burtshaver2021]

Have you used Kimpex before with good luck? I really can’t comment if it’s a concern. Curious though what part of the world are you from?

 

[Travisgg]

Have you used Kimpex before with good luck? I really can’t comment if it’s a concern. Curious though what part of the world are you from?

In Canada. Yeah there are a big supplier of powersports up here. The only reason I was asking is my last WSM wrist pin bearing was a darker aluminum.

Looks like the supplier is Namura for these bearings.
Bearings – Namura
Well maybe they're fine just makes a guy nervous when you're used to seeing them the same way all the time, and then they look different all of a sudden.

 

[burtshaver2021]

Myself, I wouldn’t be concerned and now that I’m thinking of it the 2 sets of SPI pistons I got from Royal Distributing, the needle bearings where pretty much the exact same colour as you have, they have been fine so far.

 

[Travisgg]

Myself, I wouldn’t be concerned and now that I’m thinking of it the 2 sets of SPI pistons I got from Royal Distributing, the needle bearings where pretty much the exact same colour as you have, they have been fine so far.

Oh and i am in Saskatchewan. Was thinking you were in the USA.

 

[burtshaver2021]

No, I’m in Ontario. I was thinking maybe you were in Ottawa which isn’t to far from me

 

[burtshaver2021]

As Don Cherry would say “ A good Canadian Boy”

 

[mikidymac]

I have never seen them like that either and it would give me pause too.
Never heard of Kimpex.
I stick with name brand engine parts like Pro-X and WSM.

 

[Travisgg]

I have never seen them like that either and it would give me pause too.
Never heard of Kimpex.
I stick with name brand engine parts like Pro-X and WSM.

Don't tell me that i just got over it finally lol

 

[mikidymac]

Don't tell me that i just got over it finally lol

 

[Travisgg]

Darn it...you got in my head lol

 

[mikidymac]

Honestly, looks much better.

 

[Travisgg]

Hey when you trim the rave valve do you just trim the tallest edge of it or do you try to shave the whole face of it. Know what i mean? Either way the tallest edge gets trimmed down just wondering if the whole face needs to come back as well...

 

[Travisgg]

Hey when you trim the rave valve do you just trim the tallest edge of it or do you try to shave the whole face of it. Know what i mean? Either way the tallest edge gets trimmed down just wondering if the whole face needs to come back as well...

So can I just trim the part where the red dot edge is are or do the blue dots edge need to move back in unison as well...

 

[burtshaver2021]

Be interesting to see what the guys say that know, I found this video which is interesting. Seems to make sense. Are there any specs in the manual for machining

 

[Travisgg]

Be interesting to see what the guys say that know, I found this video which is interesting. Seems to make sense. Are there any specs in the manual for machining

Yeah I saw that one. Yeah I got the proper specs... not much needs to come off. Just wasn't sure still if it's mainly the top edge or the whole face of it. The other thing is if you're using the old piston and your new piston is oversized, it wouldn't have the exact proper curvature, as the new piston is oversized in this case, but maybe it's not enough to hurt anything. I would have been smart if I used the new piston to shave it LOL. Whoops.