Another seized motor thread! This time it happened to me.

[Workinonjunk]

Ok so I’ll try to make this as short as possible, took out my 96seadoo gti for the second time this season, had zero issues with it a couple weeks ago had a long 4 hour ride.. took it out today it ran fine for a bit, then stalled randomly which is odd because it never does that, but cranked right back up. Fast forward 45 - hour an a half of riding i stopped took a break, started again and somehow a small section of rope that some lovely fellow must have cut off their boat, wrapped around my driveshaft. I found out immediately when the thing kept cavitating, so i went in the water and felt around and got the rope off with a knife. Meanwhile it kept stalling over and over as well. it seemed good after the rope was off aside from random stalling here and there over like 10 minutes of riding so i popped new spark plugs in because they were a season old and i thought it fixed it, but it started stalling again at any speed but running just fine other than that. I felt the head and pipe and it was warm but it seems like it was a normal temp. ( i do not have a working overheat gauge ). So i stopped let it cool while i got something to eat and checked it over again as best i could, and couldnt tell anything wrong with it, i took the plugs back out and closed the gap a bit because i forgot to gap them correctly first and they looked normal color. The ones i took out were e3 plugs and they were pretty black, The new ones are ngk Btw i gapped them by eye but just barely closed them since they come gapped at .30 and i run mine at .23. Anyways, i took off and about 3 minutes passed and i was hauling back to the boat ramp because i know something aint right, and it stalled again a couple times and then suddenly click click click, oh great…. I fealt the head, it was then pretty hot more than normal. Then took the pto cover off, and sure enough cant budge it. Had a buddy tow me miles back to the ramp. Pulled the plugs to see if i could free it up but no luck and then noticed the electrodes were pure white… im unsure how that could be since i had just pulled them and they looked a normal carmel color and then 3 mins later the motor locks up and am assuming no oil since they are lean looking plugs.. anyways thats as far as ive gotten with it since this just happened. Any input on what it could have been that caused it and my options would be appreciated ( i already know my wallets not looking good) btw the ski is pretty clean and sending it to a junkyard is out of question, probably.. also im not near rich, which is why im on this forum and riding a 26 yea old ski, its older than i am. Also ive been running lucas api-tc semi synthetic oil. Rebuild the carbs last year and new fuel lines. Is it possible the oiler just quit? How should i go about testing it and is there a chance i get this motor unlocked that it will work again lol. Also since it got something stuck around the drive shaft could that have something to do with it? I originally thought it sucked up something(the damn rope) n clogged the cooling system but after seeing those plugs im not sure.. anyways thanks guys

 

[Workinonjunk]

Took the head off, a bolt broke which just adds to my headache. Pistons and cylinder walls seem good. Its extremely difficult to turn, and it doesnt get any easier. So i dont know if it should be called a locked up motor at this point but it is very clearly unhappy and it also doesn’t sound too good while it is turning. It seems to get to a certain point in the stroke where it’s basically impossible to turn..

 

[JC-SUPERJET]

Pull the Pump and see if the Crank shaft and the Impeller will each turn separately.

If you're lucky, maybe it's just the Impeller that's stuck.

 

[Workinonjunk]

Pull the Pump and see if the Crank shaft and the Impeller will each turn separately.

If you're lucky, maybe it's just the Impeller that's stuck.

I can grab the drive shaft and shift it, it had a slight amount of play and it will turn separately from the crank just a little bit, so i dont think thats the issue. Along with all the other stuff that was going on, and the spark plugs, i think the crank is seized, or possibly the rotary valve i saw something about it possibly getting broken or bent and seizing the motor, and something about it being fixable. but i cant find the forum that i saw ages ago.. but i may as well pull the pump
if im gonna be pulling the motor anyways unless that rotary valve is the issue and is fixable

 

[mikidymac]

You are going to have to pull the pump to pull the engine so you might as well check that first instead of guessing.

 

[Workinonjunk]

You are going to have to pull the pump to pull the engine so you might as well check that first instead of guessing.

Agreed

 

[Workinonjunk]

You are going to have to pull the pump to pull the engine so you might as well check that first instead of guessing.

Pulled the pump, and of course no good news, other than the pump seems to be in great shape still, which is no surprise since i checked it last year when i bought it (the seadoo).. this is the least of my concerns right now of course but is the neoprene seal usable after a year or should i plan on getting another? Anyways, any input anyone has as to what to look for when tearing it apart as far as the cause of this catastrophe (assuming the carbs are good since I rebuilt them last year and put probably 15-24 hours on it since then). Basically im of course weighing my options here as far as rebuilding the whole thing my self (or just the bottom end but that could be a bad idea?), or going with a sbt for simplicity plus a warranty, altho im sure those motors could be a hit or miss but so could mine if i mess up or something goes wrong, and plus i dont give myself a warranty lol. Another thing im taking into account is the seemingly lengthy wait times for sbt to send anything and whether i buy a motor or just rebuild parts. They seem to want core first and they have 8-10 week turnover times for the 720 for some reason. Like i have 2+ months to wait -_- season will be over just about by then.. whats the quickest way to get it back going right? Im talkin weeks or days not months and i dont wanna buy a 650$ crank. Also i have 2 motor cores not sure how much sbt will give for an extra core or if the parts are even desirable. Sorry for the long ranting post!

 

[JC-SUPERJET]

Always a good idea to, at the very minimum, disassemble, clean and inspect the Carbs and entire Fuel System, whenever a Fresh Top End or Engine is installed.

Don't risk burning up $1000 + on a new Engine or Fresh Top End just to save $100 bucks on the Carbs. Not to mention the Wasted Time, the Down Time and the Sad Time.

SBT sells de-tuned Engines (Modified Cylinder Heads) so their Engines will outlast the Warranty under light duty service.

Full Bore might return you a Rebuilt Engine after a year. They do good work though, but what good is that if you miss a whole year?

In Normal Times, a 2 Week turn-around time would be excellent. 3 to 4 Weeks turn-around time for a Jetski Shop is normal.

It all depends on the Rebuild Parts availability, Shipping times and Shop Work backlog.

And of course, right now in the Jetski Peak Season...

Good luck.

 

[newtomedoo22]

SBT sells de-tuned Engines (Modified Cylinder Heads) so their Engines will outlast the Warranty under light duty service.

So for just the casual rider these engines should be just fine? I am also considering going this route as SBT is just an hour or so from home. I thought that they shipped you an engine first and then you returned your core in a week or so? My plans for any use out of my machine for this season where thrown out the window long ago. The more posts I read on this forum , the larger my to-do list gets..

 

[Workinonjunk]

Always a good idea to, at the very minimum, disassemble, clean and inspect the Carbs and entire Fuel System, whenever a Fresh Top End or Engine is installed.

Don't risk burning up $1000 + on a new Engine or Fresh Top End just to save $100 bucks on the Carbs. Not to mention the Wasted Time, the Down Time and the Sad Time.

SBT sells de-tuned Engines (Modified Cylinder Heads) so their Engines will outlast the Warranty under light duty service.

Full Bore might return you a Rebuilt Engine after a year. They do good work though, but what good is that if you miss a whole year?

In Normal Times, a 2 Week turn-around time would be excellent. 3 to 4 Weeks turn-around time for a Jetski Shop is normal.

It all depends on the Rebuild Parts availability, Shipping times and Shop Work backlog.

And of course, right now in the Jetski Peak Season...

Good luck.

Thanks for the reply, agreed about the carbs im of course gonna go through everything i can think of while its all apart. Im also confused about the detuned engines part.. ive never heard this and have another ski with an sbt in it, and have read tons on this forum.. what do you mean by light duty service? Are you saying light duty maintenance or light duty use lol. We all know theres no light use of these things lol.. and yea i dont want to wait a year especially since im probably capable of building it myself

 

[JC-SUPERJET]

Light Duty as in Recreational Riding. No Racing. No Rental. No Heavy Towing. No Big Wave Jumping. No Guts. Just Casual Weekend Riding.

You don't disassemble SBT Short Blocks as it voids the Warranty.

SBT machines the Cylinder Head Domes bigger and changes the Squish to lower the Compression and Power Output. By doing so, there is less wear and tear on the Engine Components, thus it lasts longer and keeps the Warranty Claims down.

SBT also only rebuilds the Cylinders Bores that need it. So some SBT Engines leave their Shop with different Bore and Piston Sizes. And different Cylinder Compressions. Not an ideally balanced Rotating/Reciprocating Assembly. But it'll do for most.

Personally, I want my Engine to at least perform to New OEM Standards. I want all Cylinders to have the same matching Bore Size and Pistons. I want my Squish and Dome Sizes to be OEM. If it came with 150 psi New from the Factory, then I want about the same on my Rebuilt Engine.

It is what it is. For many on a Tight Budget and Schedule with Basic Wrenching Skills, SBT is the Solution.

 

[newtomedoo22]

Light Duty as in Recreational Riding. No Racing. No Rental. No Heavy Towing. No Big Wave Jumping. No Guts. Just Casual Weekend Riding.

You don't disassemble SBT Short Blocks as it voids the Warranty.

SBT machines the Cylinder Head Domes bigger and changes the Squish to lower the Compression and Power Output. By doing so, there is less wear and tear on the Engine Components, thus it lasts longer and keeps the Warranty Claims down.

SBT also only rebuilds the Cylinders Bores that need it. So some SBT Engines leave their Shop with different Bore and Piston Sizes. And different Cylinder Compressions. Not an ideally balanced Rotating/Reciprocating Assembly. But it'll do for most.

Personally, I want my Engine to at least perform to New OEM Standards. I want all Cylinders to have the same matching Bore Size and Pistons. I want my Squish and Dome Sizes to be OEM. If it came with 150 psi New from the Factory, then I want about the same on my Rebuilt Engine.

It is what it is. For many on a Tight Budget and Schedule with Basic Wrenching Skills, SBT is the Solution.

Thank You for explaining it so thoroughly! Thats exactly all I need personally. Casual riding and some degree of reliability are what I'm looking for.

 

[Workinonjunk]

Light Duty as in Recreational Riding. No Racing. No Rental. No Heavy Towing. No Big Wave Jumping. No Guts. Just Casual Weekend Riding.

You don't disassemble SBT Short Blocks as it voids the Warranty.

SBT machines the Cylinder Head Domes bigger and changes the Squish to lower the Compression and Power Output. By doing so, there is less wear and tear on the Engine Components, thus it lasts longer and keeps the Warranty Claims down.

SBT also only rebuilds the Cylinders Bores that need it. So some SBT Engines leave their Shop with different Bore and Piston Sizes. And different Cylinder Compressions. Not an ideally balanced Rotating/Reciprocating Assembly. But it'll do for most.

Personally, I want my Engine to at least perform to New OEM Standards. I want all Cylinders to have the same matching Bore Size and Pistons. I want my Squish and Dome Sizes to be OEM. If it came with 150 psi New from the Factory, then I want about the same on my Rebuilt Engine.

It is what it is. For many on a Tight Budget and Schedule with Basic Wrenching Skills, SBT is the Solution.

Awesome info! Especially since sbt doesn’t explicitly say any of this themselves, which ive been contacting them with no luck so far hopefully i can get a response from them to hear it from them. Im obviously not looking for a mean racing machine i mean its a 96 gti haha but i want it to at least perform as good as it was because it was actually quite impressive for what it is.. but still havent torn my motor down yet so i dont knowwhat im going to do because i think id rather rebuild it back to oem spec if the price is within reason (around 1k) but i know it depends what i need and ive yet to actually take it apart yet. Stupid work getting in the way of me spending all my free time and money!

 

[newtomedoo22]

Stupid work getting in the way of me spending all my free time and money!

I have that very same problem!

 

[Workinonjunk]

Also are you implying that you figure sbt is actually more reliable than oem because less performance?

 

[Workinonjunk]

Light Duty as in Recreational Riding. No Racing. No Rental. No Heavy Towing. No Big Wave Jumping. No Guts. Just Casual Weekend Riding.

You don't disassemble SBT Short Blocks as it voids the Warranty.

SBT machines the Cylinder Head Domes bigger and changes the Squish to lower the Compression and Power Output. By doing so, there is less wear and tear on the Engine Components, thus it lasts longer and keeps the Warranty Claims down.

SBT also only rebuilds the Cylinders Bores that need it. So some SBT Engines leave their Shop with different Bore and Piston Sizes. And different Cylinder Compressions. Not an ideally balanced Rotating/Reciprocating Assembly. But it'll do for most.

Personally, I want my Engine to at least perform to New OEM Standards. I want all Cylinders to have the same matching Bore Size and Pistons. I want my Squish and Dome Sizes to be OEM. If it came with 150 psi New from the Factory, then I want about the same on my Rebuilt Engine.

It is what it is. For many on a Tight Budget and Schedule with Basic Wrenching Skills, SBT is the Solution.

Another thing about this that ive been thinking about is, why would they need to lower the compression and power output to mitigate the amount of warranty claims, when the oem seadoo motors generally have zero issues especially in the span of 1-2 years which is all the time their warranty covers… for example i know that these 720 motors as well as 787s have a pretty long lifespan if reasonably taken care of. Ive heard its pretty common to get 3-400 hours out of a top end in these motors and some have had upwards of 1k hours on the bottom. I dont know anyone that puts that kind of hours or even close to it in a year..

 

[mikidymac]

Also are you implying that you figure sbt is actually more reliable than oem because less performance?

No, not even close to OEM, less performance, less reliability and less longevity. As they say you get what you pay for.

The reason is lower quality parts and lower tolerances in an attempt to cut costs and increase profits. That is why they have to lower performance to make it survive past the warranty period.

 

[Workinonjunk]

No, not even close to OEM, less performance, less reliability and less longevity. As they say you get what you pay for.

The reason is lower quality parts and lower tolerances in an attempt to cut costs and increase profits. That is why they have to lower performance to make it survive past the warranty period.

Well as much as i dont like to hear that because its the simplest fix plus ive always heard they were the only company who even stands a chance at making motors that are as good as the original. But it sounds like its a dice toss as far as what i might get.. well knowing all that info lets say i want to rebuild it myself and make it as reliable as possible without spending top dollar on all the parts, what kits should i buy? From what i understand is the rebuilt cranks that sbt sells and pwcmotor.com sells is that they are supposed to be decent. Is there anyone else who rebuilds them or sells rebuilt ones or is there new ones that dont cost $550+? It seems a bit ridiculous that a 2 stroke crankshaft should cost 650.

 

[Workinonjunk]

Also wondering, if i do decide to go with an expensive new crank, it’s probably best to have the cylinders honed or bored out and do new pistons and rings right? Or might that not be necessary? I know i need to check the ring gap and clearance to really know and also check for any scoring or gouging. But if all of that checks out good could it still be possible that the pistons are weakened from whatever happened to it? Also do these cylinders need to be re-plated after boring because on 2 stroke dirtbikes they must get plated.. thanks

 

[POPPS]

No,,,the cylinders can’t be replaTed,,they can be honed…bored…or replaced,,I would,,,take the entire motor apart,,,and see if if the crank is fine,,,and brass gear is fine,,,and counter balancer gear and or bearings are fine,,,
At our shop,,,we look at the “over” on the piston domes,,,the ,let’s say they are .5mm over,,,so then we take the barrels to our nearby machine shop (lucky us)…10 minutes away,,,with 2 new pistons that are .75 over,,,they clean out the bores to the tolerances of the new pistons,,,and voila…we put everything else together ourselves,,,when you are racing you better know how to do almost everything yourself.
So if the lower end parts are good,,,you can just rebuild the top end yourself,,,Unfortunately,,,if the crank is gone, you will need to replace it,,,there are crank rebuild kits,,,but the problem is trying to find a machine shop that rebuilds watercraft cranks,,,the cost may be the same,,,but at least you will have full control in the process,,,and it will not take for ever,,,
Our nearby machine shop usually does the work in 1 week,,,the cost here to bore is about $90 Canadian,,,of course,,,if you just need a light honing,,,you can do that yourself,,,you can buy a honing kit…and there are tube videos on the process,,,For 4tecs…we get long blocks from SBT…otherwise for the 2 strokes,,,we will buy the new crank and rebuild the engine,,,at least this way…if the head was good,,,the squish stays the same,,,and if just one side of the head is a bit damaged you can clean it up with a die grinder,,,,or find a used head on line,,,just make sure ask that the head is virgin,,,not cut or “squished”
Hope these ideas and notions help,,,this is how we approach engine rebuilds,,,and have yet to have a failure that was our fault.

 

[Workinonjunk]

No,,,the cylinders can’t be replaTed,,they can be honed…bored…or replaced,,I would,,,take the entire motor apart,,,and see if if the crank is fine,,,and brass gear is fine,,,and counter balancer gear and or bearings are fine,,,
At our shop,,,we look at the “over” on the piston domes,,,the ,let’s say they are .5mm over,,,so then we take the barrels to our nearby machine shop (lucky us)…10 minutes away,,,with 2 new pistons that are .75 over,,,they clean out the bores to the tolerances of the new pistons,,,and voila…we put everything else together ourselves,,,when you are racing you better know how to do almost everything yourself.
So if the lower end parts are good,,,you can just rebuild the top end yourself,,,Unfortunately,,,if the crank is gone, you will need to replace it,,,there are crank rebuild kits,,,but the problem is trying to find a machine shop that rebuilds watercraft cranks,,,the cost may be the same,,,but at least you will have full control in the process,,,and it will not take for ever,,,
Our nearby machine shop usually does the work in 1 week,,,the cost here to bore is about $90 Canadian,,,of course,,,if you just need a light honing,,,you can do that yourself,,,you can buy a honing kit…and there are tube videos on the process,,,For 4tecs…we get long blocks from SBT…otherwise for the 2 strokes,,,we will buy the new crank and rebuild the engine,,,at least this way…if the head was good,,,the squish stays the same,,,and if just one side of the head is a bit damaged you can clean it up with a die grinder,,,,or find a used head on line,,,just make sure ask that the head is virgin,,,not cut or “squished”
Hope these ideas and notions help,,,this is how we approach engine rebuilds,,,and have yet to have a failure that was our fault.

Thank you so much, definitely a helpful reply. Ok so a few questions + input id like to add so people understand more fully my motors condition. I still didnt take any part of the motor apart other than the head. From what i can see which isnt a whole lot of course. But the pistons seem to be fine and dont think they were what seized at all. This is still “guessing” i suppose and i need to take the cylinders off and check for wear but im certain the compression was good before this happened and am confident nothing even happened in the top end whatsoever. I believe the crank simply had enough and seized up which is unfortunate. So lets assume the top end is fine and maybe at most needs a quick hone go clean it up while im in there. Am i safe to put a rebuild sbt crank in it? Or is it still risky because the pistons have unknown hours on them and even if it had good compression they could be tired and more likely to grenade? Thats what i know from 2 stroke dirtbikes that they have a lifespan, and a short one at that compared to these.. as for the head, how can i check if its been altered in any way? I will post a pic if that helps.. i have another head already that seems to be in good condition that i know couldnt have been messed with.. what is squish? Also i have a machine shop that ive used for other things relatively close to me but i think having my crank rebuild locally is out of the question because i dont know of anyone who does it.. another question i have is tons of people in this forum swear by only oem parts but as of now i dont see oem engine parts available anywhere, such as crank, pistons etc..

 

[Workinonjunk]

Also i have a completely different question that could be off topic, but since i got this ski every time i hit a bigger wave and had a rough landing that really smacked down, it would stall just shut off, but always crank right back up like nothing happened. And this would happen at any throttle input. Anything that causes this that has to do with the motor? Also all the battery connections and i know the main ground were tight. It has a aftermarket cdi box as well which probably isnt a great thing, and i do have a different one but with no key and no way to test it.

 

[Workinonjunk]

Took it all apart pretty much. Top end needs to be done ive found out because i think the bottom end toasted one of the cylinders its all gouged out and so is the piston.. who knows maybe it was like that already but i am gonna be probably going with the wsm platinum pistons (+1mm over probably, im just guessing what size i need and havnt measured the bore yet) I need to know if the sbt rebuild crank is good or should i spend twice the amount for a new wsm? Do the sbt cranks have a warranty? And is the sbt full engine gasket kit any good or are they trash? Id like to start ordering parts as soon as i can so i can bring the cylinders to a machine shop with the new pistons. Yes i can order the pistons before i decide on the crank but i dont know if i want to even rebuild it if i have to buy a 650$ crank but if its that much better, maybe i will.. thanks!
Edit: i also am probably going to buy a whole new rotary shaft assembly, not just the brass gear because i dont trust any of it to be good still. So is the titan brand bay area sells good or is sbt? Is there another brand thats good or possible to buy oem somewhere?

 

[Workinonjunk]

Forgot to get pics of the cylinder but you can imagine how it matches that. Also, still unable to turn the crank at all

 

[Workinonjunk]

Another update; I decided to give sbt a call, i asked them about their crank, they do not warranty it unless it arrives broken. I asked them about their motors regarding the things that were spoken about on this thread talking about how they are performing less and less reliable and lower compression etc. they said that their compression and squish are actually “within” oem spec so id assume the difference in performance wouldnt be noticeable but maybe im wrong? Also they claim that the motors have been 100% rebuild with new parts which i have seen other threads claim that they got old parts n used bearings on cranks etc but i dont see how that could be true without them getting sued lol. They also claimed that their trued and welded crank is just as good as oem if not better. So are they completely full of it or what? Also their shipping is VERY expensive depending on where you are at..