1995 Seadoo XP Pistons

[caw0215]

Hi- I have a 1995 Seadoo XP 720. I pulled the motor to clean the crud out and see what shape those hidden areas are in. I removed the manifold to check on the pistons and could see dark stains. I read another post where it was mentioned that water in the crank could be one of the root causes (guilty). Others say rings are no longer sealing and this is 'blow-by'.

Compression is still 145+ on both but after reading more on the subject I'm finding that's not unusual and has nothing to do with piston health. Any advice on next steps?

Thanks in advance

 

[caw0215]

Ski works but needs a lot of TLC. Given to me by a neighbor that no longer wanted to maintain it. Lots of corrosion so I wanted to have a better look at the hard to see areas. Good thing, 2 motor mounts came off with the motor and the other 2 popped off with very little effort. Starter is very rough looking but works. And I'll do other stuff while it's out like rebuild the starter, drain/clean the 2 tanks, and finally get the tuning pipe fixed properly.
With the pistons I'll try what your suggest. I do believe in "if it ain't broke don't fix it" so if I can hold off on any other major expenses I'll surely wait. That being said, motor is out now. If inspecting the pistons further is a best practice I'm not against pulling the head and replace a few gaskets. Should the pistons and jugs be cleaned/polished professionally?

 

[NickCawks]

That's a bummer about the motor mounts! That will probably be the hardest thing you are facing. Not that its too hard but you do have to do some fiberglass work.

Sounds like you've been doing your research and are on the right track

Another common failure point to look into is the fuel selector.

As for the pistons. There's simply nothing you can do aside from hope that it cleans up when doing popp's suggestion.

Your compression isnt perfect but is high enough to be a good sign that the motor could still have some life in it.

If it does end up needing a rebuild, this is not something you will be able to do without certain very expensive machinery. But you can take it to a local machine shop or send it into somewhere such as fullbore.com.

You'll be looking at around 400 for a top end rebuild, but this does give you the opportunity to get some slightly larger pistons and push a minor amount more power out of the motor.

My 95 xp has 2mm overbore pistons. It definitely gained some umph when I went from stock size to those.

 

[caw0215]

Sorry wasn't clear...the motor mounts are still attached to the ski, it's the rubber connection that deteriorated. I've already received 4 replacement mounts. The original shims look rough and pitted a bit but they're still OK I guess.

Tried spraying the cleaner in thru the manifold...seems like I can only clean one area. Should I open it up to do it properly or can I go thru the spark plug hole and rotate the crankshaft?

I was just looking at fullbore. Actually leaning towards this type of option mainly because this is a 25 year old jetski, they have a good reputation, and I have no idea what the previous owners have done. Fullbore has a platinum ($300) deal where the cylinders are bored up to 0.040" (1mm) oversize w/WSM pistons . Would it be worth an extra $75 to go with Wossner pistons? And with the larger pistons...would I need to change my stock needles and/or adjustments to the carbs?

 

[caw0215]

@NickCawks I replaced the fuel selector valve and all the lines. I am not convinced though that there's not an air leak somewhere. Researching that vacuum test.

 

[Mraw]

Sorry wasn't clear...the motor mounts are still attached to the ski, it's the rubber connection that deteriorated. I've already received 4 replacement mounts. The original shims look rough and pitted a bit but they're still OK I guess.

Tried spraying the cleaner in thru the manifold...seems like I can only clean one area. Should I open it up to do it properly or can I go thru the spark plug hole and rotate the crankshaft?

I was just looking at fullbore. Actually leaning towards this type of option mainly because this is a 25 year old jetski, they have a good reputation, and I have no idea what the previous owners have done. Fullbore has a platinum ($300) deal where the cylinders are bored up to 0.040" (1mm) oversize w/WSM pistons . Would it be worth an extra $75 to go with Wossner pistons? And with the larger pistons...would I need to change my stock needles and/or adjustments to the carbs?

No adjustment to the carbs necesary. Fullbore has been reviewed poorly here recently in regards to wait time and customer service. I used 5 star PWC out of Michigan with good results. The wosners are forged so I wouldn't recommend them, i would use WSM or pro x

 

[caw0215]

ok so I removed the head. I have no idea of the history with the (free) ski. Figured might as well get in there to inspect. A can of PB blaster later 5 bolts had wrenched off. I was able to use vice grips on the stubs to remove them.

Does look like staining that should clean up but the piston closest to PTO has chipped edges at the outer edges above the ring.

1) Is this damaged to the point it should be replaced?
2) the bolts that broke I used an M11 socket but parts diagram show flanged hex screw M8x70. Am I missing something with the bolt specs? Regardless.. where can I purchase replacements? ebay shows a few used but is that my only option?
3) the cylinder has a piece chipped off the inner gasket wall. Do I need to replace the entire cylinder for this? or will the gasket still do it's job

I did speak with Dan at Full Bore about a rebuild. They will remove the flywheel ( which I know will be a pita ). And yes they have a backlog up until April and top ends min 4 weeks.

thanks in advance-
Carey

 

[mikidymac]

Pistons and cylinder are junk.

If you want it fast your only option is SBT.

Westside Powersports Seadoo can get you good cylinders.

As said above pro-x or WSM pistons are good and I have Group K do all my cylinder boring.

 

[Mraw]

Five star PWC and fresh water pwc out of Michigan are fast aswell and you can have them put in pro x

 

[caw0215]

Pandemic has caused all sorts of issues. Many many people are buying and restoring pwcs. SBT had to close their doors b/c locals would not adhere to the social distancing. Even though I live near Clearwater I still have to rely on shipping. They're out of the alignment tool but should soon have it back in stock ( or so they said 2 weeks ago ). And I'll have to have it shipped to me.
Westside Powersports not answering their phones b/c they're also too busy. Good problem to have I guess. Dan @Full Bore at least returned my call and he too is busy. Everyone is busy.
Not in a rush so will check with Mraw's recommendations.
Maybe my best bet is to just get a rebuilt engine.
Or put my 'free' doo back together and sell is 'as is'. -Thanks

 

[mikidymac]

All I can say is stay away from FullBore. They are no longer recommended here. Good work but not appropriate delays.

 

[caw0215]

OK point well taken. So I contacted Nick at westside powersports. Says he has 2 white paint 720 cylinders and matching pistons std bore shipped for $280. Wondering if it's best to get only the cylinders and have them bored to match new pistons. Thoughts? any risk with getting the std set?

 

[mikidymac]

If it was a ski I was going to keep then always bore used cylinders and new pistons sized to fit.
If I was just trying to get it running for cheap then at a minimum I would ball hone the cylinders and install new rings on the old std pistons.

 

[caw0215]

Going cheap route to get it finally on the water and see what needs to be fixed next. If Nick is up front with me (which I think he is) then I should be OK with these cylinders and pistons for at least another season.

2 questions:

• For the ball honing...Is this something you can do with a drill hone?
• is it straightforward when ordering new rings for standard bore pistons?

Thanks!

 

[mikidymac]

Yes, dingle ball hone on a drill with some WD-40.
If they are OEM pistons you have to use OEM rings.

 

[caw0215]

I received the 2 cylinders and pistons from Westside Powersports. They look decent but a little staining on top.
When cleaning the top I can see the bore size of 81.94 which is stock. When ordering new rings they should be standard bore size (82mm)..right?

I can still see some cross hatch but with new rings I know I should hone. Can someone recommend the size and recommended grit, ( amazon shows only one size and it's too small )

I did see in one post a recommendation you could use sandpaper 300+ grit and do the cross hatch pattern.

Is this OK?

 

[mikidymac]

No, you can't use sandpaper.
You need std bore OEM rings if they are OEM pistons.

290815070​

SEMI-TRAPEZ RING 82.00 MM​

2​

43.99​

Your stock bore is 3.228" so this 3.25" Flex Hone should work. Amazon Flex Hone

 

[caw0215]

180 or 240 grit? -thanks

 

[mikidymac]

Not sure or if it matters. Personally I would go 240 because you are just cleaning them up.

 

[caw0215]

Pistons are marked with Elko and 81.94 which I'm assuming is an OEM standard bore.

Are these a compatible set? or if anyone has another recommendation thanks in advance

WSM Piston Ring Set 82.00mm Bore 010-917 | eBay

 

[mikidymac]

No, you need to run OEM rings on OEM pistons as they are a different design.

 

[caw0215]

Ended up taking advantage of a black friday deal wsm platinum standard pistons top end kit for $170.
Will hold onto my used pistons as a backup they're in decent shape
Picked up the flex hone so top end should be good to go
Thanks again