What could cause case sealant failure on almost new PV motor?

Sparkplug

Sparkplug

Location
Red Bluff CA
If the bearings and journals are good. It's not gonna let go and blow.

If you want it perfect. Start fresh and get the cylinders redone, pistons. New rings. New bore. New wrist pin bearings. Yada Yada.

If you wanna ride and not blow your ski or wallet up. I'd say lightly hone it to get cross hatching back. Check the bearings and crank for runout. Put New wrist pins in cause they are 18 bucks each. And slap oem crank seals in with a new base gasket. I'd vet you 100 bucks it lasts 2 or 3 seasons of your riding. And doesn't grenade unless you hydrolock it

Sent from my SM-G991U using Tapatalk
 
Sparkplug

Sparkplug

Location
Red Bluff CA
Fun is fun. And if the engine runs good, who cares if the parts are new. Spec is spec. And if it's in spec thats all that matters. Chasing perfection as a amateur is a recipe to go broke or give up from frustration. This engine is easily fixable with minimal parts if the pics are true. Judging by the op reviews responses, he would lose this entire coming riding season if he dove into rebuilding this complete engine. What's a season of riding worth to you? To me? To whoever?

Sent from my SM-G991U using Tapatalk
 
SXIPro

SXIPro

JM781 Big Bore
Location
Here on the 'X' mostly
Sparkplug said:
Fun is fun. And if the engine runs good, who cares if the parts are new. Spec is spec. And if it's in spec thats all that matters. Chasing perfection as a amateur is a recipe to go broke or give up from frustration. This engine is easily fixable with minimal parts if the pics are true. Judging by the op reviews responses, he would lose this entire coming riding season if he dove into rebuilding this complete engine. What's a season of riding worth to you? To me? To whoever?

Sent from my SM-G991U using Tapatalk
Click to expand...
A new Matador, a new mastodon, a Maverick
A Mustang, a Montego, a Merc Montclair
A Mark IV, a meteor, a Mercedes, an MG
Or a Malibu, a Mort Moriarty, a Maserati
A Mac truck, a Mazda, a new Monza, or a moped
A Winnebago, hell, a herd of Winnebagos
We're giving 'em away
Or how about a McCulloch chainsaw?
Or a baby's arm holding an apple?
 
JKMike

JKMike

Location
Annapolis, Maryland
So here are the measurements I got.
Fwd Piston Skirt Diameter: 3.6392"
Aft Piston Skirt Diameter: 3.6385"

Here are the bore measurements. FYI: The. first # is line with the exhaust port (Port -Stbd) and the second # is 90 deg from there (Fwd - AFT)

Fwd Bore:
Top 3/8" below deck: 3.6448" and 3.6465"
Middle just above exhaust port: 3.6454" and 3.6456
Middle below exhaust ports 3.6455" and 3.6454"
3/4" above bottom of cylinder: 3.6445" and 3.6455"

Aft Bore:
Top 3/8" below deck: 3.6442" and 3.6468"
Middle just above exhaust port: 3.6450" and 3.6455"
Middle below exhaust ports 3.6460" and 3.6454"
3/4" above bottom of cylinder: 3.6455" and 3.6455"

Piston Clearance going off a bore diameter of 3.6455"
Fwd piston clearance: 0.0063"
Aft piston clearance: 0.0070"

I also checked the ring gap for the rings on the Aft Cylinder and these numbers have me very concerned!!! Can someone please tell me if these are as bad as I think or do these larger motors just need more of a gap????

Top Ring Gap: 0.029"
Bottom Ring Gap: 0.030"
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
What kind of pistons are in it, it matters because you might get away with that clearance on forged pistons but for cast pistons you are way out of whack.
 
Harbor

Harbor

Location
Stockton
JKMike said:
They are forged Wiseco pistons. I have an email in to Xscream asking for more information as well as specs for piston clearance and ring gap.
Click to expand...
This is good you’re getting their specs!

Reason I say that is, I bought an advertised good ready to go Stroker cylinder, new pistons and 8 mil crank from a jet ski shop.. cyl and crank had light use… well I needed cases and my cases couldn’t be trenched without them having the crank for clearance checks… I ended up sending all of it to Brian virgin from Thrust innovations… he measured my piston clearance @ nearly .007 and would need a rebore.. clearance was to large to transfer heat correctly among other things…wisco forged pistons, I asked what should it be, more like .0045 to .005 on mine ?

The seller says he sets his up loose at .0065 for racing and it’s fine.

Who’s right ?

Iam not racing so opted for Brian’s advice either get a rebore and more new pistons…or buy bigger sleeves and new pistons ? I went with sleeves and new pistons… turns out the crank was out of phase as well…best thing I did was send it in and not believe the sells poo…

My bores do seem to show wear like you have pictured though… seemingly early on too.. a little alarming but I’ve gotten used to it..

Wonder if the seller on yours, looked at the bores but didn’t mic them, and did a light hone with new pistons ? So you have old and new wear showing ?
 
Last edited:
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Harbor said:
This is good you’re getting their specs!

Reason I say that is, I bought an advertised good ready to go Stroker cylinder, new pistons and 8 mil crank from a jet ski shop.. cyl and crank had light use… well I needed cases and my cases couldn’t be trenched without them having the crank for clearance checks… I ended up sending all of it to Brian virgin from Thrust innovations… he measured my piston clearance @ nearly .007 and would need a rebore.. clearance was to large to transfer heat correctly among other things…wisco forged pistons, more like .0045 clearance max ?

The seller says he sets his up loose at .0065 for racing and it’s fine.

Who’s right ?

Iam not racing so opted for Brian’s advice either get a rebore and more new pistons…or buy bigger sleeves and new pistons ? I went with sleeves and new pistons… turns out the crank was out of phase as well…best thing I did was send it in and not believe the sells poo…

My bores do seem to show wear like you have pictured though… seemingly early on too.. a little alarming but I’ve gotten used to it..

Wonder if the seller on yours, looked at the bores but didn’t mic them, and did a light hone with new pistons ? So you have old and new wear showing ?
Click to expand...
Personally I would not run Wisecos at .0045 clearance more like .0055 or .0060 , they expand a lot , cast pistons would run at .0004 all day long, here is my take there are specs that will work and specs that will work well, the difference is .0001 or .0002 , back when I first started building Seadoo engines they were set up at .002 - .0025 this was the factory spec, of course they were seizing left and right as .002 left no room for operator or mechanical errors.

Seadoo of course claimed it was from improper break-in , their recommend break -in time was 10 hrs , not many customers would go for that but if you are set up at .0025 it is totally necessary to do it or the engine would seize up. my theory is you set it up at the proper clearance or the engine will make it's own clearance the hard way.

I bumped the spec to .004 just like I had been setting up the Kawi 650 and 750 engines using cast pistons and all was right with the world again , I played around with the clearances a bit , after .004 it got a little noisy but still ran just fine, at one point in time we were having 10 587 cylinders bored at a time..
 
Last edited:
DylanS

DylanS

Gorilla Smasher
Location
Lebanon Pa
I will be impressed if they hand their specs out without you having directly purchased the motor from them tbh but I’ve never dealt with xscream
Just typically feels like pulling teeth when trying to deal with some of these companies after purchasing a engine second hand…
 
wikstromm

wikstromm

Washed up hillbilly
Location
SE
DylanS said:
I will be impressed if they hand their specs out without you having directly purchased the motor from them tbh but I’ve never dealt with xscream
Just typically feels like pulling teeth when trying to deal with some of these companies after purchasing a engine second hand…
Click to expand...
Rick at xscream has helped me with all my specs for my used xs motor, orderd pistons and gasgets from them, very helpful and fast replys.
 
Harbor

Harbor

Location
Stockton
WFO Speedracer said:
Personally I would not run Wisecos at .0045 clearance more like .0055 or .0060 , they expand a lot , cast pistons would run at .0004 all day long, here is my take there are specs that will work and specs that will work well, the difference is .0001 or .0002 , back when I first started building Seadoo engines they were set up at .002 - .0025 this was the factory spec, of course they were seizing left and right as .002 left no room for operator or mechanical errors.

Seadoo of course claimed it was from improper break-in , their recommend break -in time was 10 hrs , not many customers would go for that but if you are set up at .0025 it is totally necessary to do it or the engine would seize up. my theory is you set it up at the proper clearance or the engine will make it's own clearance the hard way.

I bumped the spec to .004 just like I had been setting up the Kawi 650 and 750 engines using cast pistons and all was right with the world again , I played around with the clearances a bit , after .004 it got a little noisy but still ran just fine, at one point in time we were having 10 587 cylinders bored at a time..
Click to expand...
He’s getting specs from Xscream, they could very well call for .0065 on his 10 port cylinder…
 
JKMike

JKMike

Location
Annapolis, Maryland
Per XScream the piston to wall clearance should be 0.005" - 0.007 and the rings should be gapped to 0.030" - 0.033". Not what i was expecting but i am certainly relieved to hear im still in spec.

I was also told I should shoot for around 110deg F at the base of the cylinder front and back immediately after running it hard. I had been taking my temps closer to the top of the cylinder and was also shooting for a little bit higher temps so maybe that's part of my problem.

I have a Lisle hone on the way and just got one of the Wiseco nlyon finishing brushes so my plan is currently to lightly hone both, just to get a little more visible crosshatching and then give it just a couple passes with the brush. I'm also going to touch up the chamfers in a few of the ports because I'm pretty sure some of the scuffing is from catching an edge or two on those. The bottom of the cylinder could use some work as well because those edges are pretty sharp and I can match up the scuffing on the skirt coating with several spots down there.

Overall It sounds like I'm not in as bad of shape as I thought so that's a relief!
 
fastgtfairlane

fastgtfairlane

Location
Charlotte, NC
I'm not expert by any means with engine diagnosis but it definitely looked to me like it got a little hot by the scuff marks on both intake and exhaust sides. The billet cylinders retain a bit more heat than the cast cylinders do so they need more water flow. I helped a friend put a trinity matrix together with a ss900 engine. We set up his cooling as follows and this is in the south with 90+ degree water temps. 2- 1/2 lines feed a manifold with 4 3/8 lines going out. 2 feed the top of the head and out of the exhaust manifold to pissers, one feeds the spray bar and the last feeds the stinger with a flow control and another pisser. This was with a powerfactor ran wet.
 
WFO Speedracer

WFO Speedracer

A lifetime ban is like a lifetime warranty !
Location
Alabama
Sorry he confused me with the bore size in inches, I am used to dealing in mm, but yes I can see running .006-.007 with a 92.5 mm bore.
 
You must log in or register to reply here.
Top Bottom