Lil Engine issue

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etemplet

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Guy brought me a couple skis to look at. He told me this one was running all day and they brought it home and began flushing it. Water came out from everywhere and they found chunks of metal under the engine The engine turned fine. I'll even be the compression was good. Check this out. Kinda difficult for me to believe the rider didn't hear something. GTX Broke Casing.JPG
 
There is no way that thing was running perfectly fine.

Send it to SBT, should be a good core.
 
We pulled the engine apart... it's junk. Kept the cylinders, starter, head and mag parts.. Rest is trash. Gear on the crank is toast. Crank also lost a bearing on the Mag side. KA BOOM !!! Already got my spare engine in there. Looking at the carbs Now. I thought I had a picture of the crank. Oh Well. :D
 
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GTX Engine Balance Shaft.jpeg
There is no way that thing was running perfectly fine.

Send it to SBT, should be a good core.
Not familiar with SBT but the engine has a tag that says SBT. Quite clear that the bearing on the balance shaft let go. Isn't that a seal bearing on that end of the balance shaft? I've read they use cheap bearings.....Hmmmmmmm....
 
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Well, another mark against SBT, yes that is a sealed bearing and should not have failed if it was a quality part. But hey, they have a 1 year warranty, LOL.
 
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Any idea why sbt welds cranks? I might be looking for a 787 crank.
I don't think it has ever been answered. It is uncommon for any seadoo to twist a crank and nobody else does it even the factory.

I would look at OEM cranks since I am sure shipping from SBT to Alaska would be ridiculous.
 
There is no way that thing was running perfectly fine.

Send it to SBT, should be a good core.
I just wonder how much noise it made when all this happened. I'd think the ski had a hell of a vibration during and after. Funny thing though.... you couldn't see any of the damage from the top and the crank turned as it should. Nice and smoothing by hand.
 
Any idea why sbt welds cranks? I might be looking for a 787 crank.

I have a SBT welded crank I picked up for the 97' GTX project last year. Yes, they do weld the pins, something to do with that when you reman and reassemble, you could get crank twist. I'm sure a new crank it's fine, crank twist shouldn't happen, so this is why they weld the pins. They still take back their own welded cranks later, I did ask that question when they called to review the core return policy.

I have no issue thus far with it, prompt shipping, easy to rebox my core and drop it off at the nearest FEDEX. One shipping charge that covers the return. I hear they use cheap bearings, but only time will tell on that one. Right now, a 787 carb crankshaft just went to $295 plus shipping, with a good core return. I'm about to place an order next week for another one to finish the 96' GSX resto project I'm working on. The crank I have isn't too bad, just one of the inner bearings is a little noisy.
 
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I have a SBT welded crank I picked up for the 97' GTX project last year. Yes, they do weld the pins, something to do with that when you reman and reassemble, you could get crank twist. I'm sure a new crank it's fine, crank twist shouldn't happen, so this is why they weld the pins. They still take back their own welded cranks later, I did ask that question when they called to review the core return policy.

I have no issue thus far with it, prompt shipping, easy to rebox my core and drop it off at the nearest FEDEX. One shipping charge that covers the return. I hear they use cheap bearings, but only time will tell on that one. Right now, a 787 carb crankshaft just went to $295 plus shipping, with a good core return. I'm about to place an order next week for another one to finish the 96' GSX resto project I'm working on. The crank I have isn't too bad, just one of the inner bearings is a little noisy.

The big issue with SBT is the shipping charges, the farther you are from them the worse it is.
So for me in California the last time I checked a 787 crank was $295 with almost $100 in shipping from SBT. I asked if I could cover shipping since there is no way it is $100 to ship especially with my commercial rate and they said no, you have to use our shipping. I can only assume they are using it as shipping and "handling" to get more money.
Now an OEM crank from Pro Caliber is $373 with free shipping to me and about $25 for me to ship the core back.
So SBT = $395 and OEM is $$398 for me in California. OEM bearings vs. Chinese.
 
The big issue with SBT is the shipping charges, the farther you are from them the worse it is.
So for me in California the last time I checked a 787 crank was $295 with almost $100 in shipping from SBT. I asked if I could cover shipping since there is no way it is $100 to ship especially with my commercial rate and they said no, you have to use our shipping. I can only assume they are using it as shipping and "handling" to get more money.
Now an OEM crank from Pro Caliber is $373 with free shipping to me and about $25 for me to ship the core back.
So SBT = $395 and OEM is $$398 for me in California. OEM bearings vs. Chinese.

I can see CA being more, I looked it up, I paid $60 for to/return shipping for AL last year from SBT on the crank.

There's been discussions about bearings before on other forums, most people are not having issues at all. The ones having bearing issues are high hour machines. I've heard conflicting information about where SBT sources their bearings, some say china, others say china doesn't source their crank bearings, but the smaller bearings. They reman thousands of engines, I'm sure if failures were happening with bearings they would source elsewhere. But something tells me they buy good bearings in bulk to get the cost down.

I bought a NOS Nachi (japanese) bearing for the balance shaft recently, to the consumer buying a single bearing, a cheap chinese bearing is about half to a third as much as a 'good' bearing. I paid about $9 total. But if you buy 100 or a 1000...

I think eventually all bearings wear out regardless cheap or not.
 
I can see CA being more, I looked it up, I paid $60 for to/return shipping for AL last year from SBT on the crank.

There's been discussions about bearings before on other forums, most people are not having issues at all. The ones having bearing issues are high hour machines. I've heard conflicting information about where SBT sources their bearings, some say china, others say china doesn't source their crank bearings, but the smaller bearings. They reman thousands of engines, I'm sure if failures were happening with bearings they would source elsewhere. But something tells me they buy good bearings in bulk to get the cost down.

I bought a NOS Nachi (japanese) bearing for the balance shaft recently, to the consumer buying a single bearing, a cheap chinese bearing is about half to a third as much as a 'good' bearing. I paid about $9 total. But if you buy 100 or a 1000...

I think eventually all bearings wear out regardless cheap or not.
SBT uses Chinese bearings and have even confirmed they use Chinese bearings. Now I am not saying that all Chinese bearings are bad and I am sure you can get good and bad ones. A few years ago SBT had a lot of crank bearing failures and that gave them a really bad name but they admitted they have changed things and they have become more reliable.

While I am not saying that SBT cranks are bad or will fail, what I am saying for basically the same price you can get an OEM crank using known high quality bearings, parts and to OEM specs so for me I go OEM. Also look at all the performance engine builders squeezing more power out of these engines and not a single one will ever tell you to use a SBT crank, they all say use and OEM crank or a high end crank builder like Competitive Crankshafts. Everyone will tell you SBT is ok for stock rebuild but nothing more.
 
Everyone will tell you SBT is ok for stock rebuild but nothing more.

Yep, stock rebuild, that's me, maybe some performance add ons later. Plenty others getting them from SBT for stock rebuild and some performance modding them. I'm not hitting the racing circuit anytime soon.

If I get about 5-7 years and or about 150 hours out of it I'm thinking $300 for a crankshaft from SBT was a good deal.
 
Yep, stock rebuild, that's me, maybe some performance add ons later. Plenty others getting them from SBT for stock rebuild and some performance modding them. I'm not hitting the racing circuit anytime soon.

If I get about 5-7 years and or about 150 hours out of it I'm thinking $300 for a crankshaft from SBT was a good deal.

Yes, If I lived closer I would probably consider them more. I am using one of their Yamaha 701 cranks in my superjet that will be mostly stock. There is a vendor that resells them for $280 shipped and no core, one from Yamaha is $983.
 
There is no way that thing was running perfectly fine. ...

Agreed, this and the OP reminded me of what I observed one evening, earlier this week: we live smack on the lakeshore and, as I’m finishing up working in the yard I hear the weirdest “moan, Mooan, MOANNNNN!” coming from the main channel. I stick my head out of the shed thinking, “Either someone is trying to porpoise their ski or somebody is gonna need help shortly...” and see a rider (the ski was too far away for me to ID a make or model) glued to the throttle despite the gosh awful noises coming from the machine. So, now I’m thinking, “Must be intent on making it to the boat ramp, looks like they’re gonna make it, okay” and I go back to work. Ha! Half an hour later; you guessed it, same ski now returning in the opposite direction and same gosh awful straining noises. You can see the engine was struggling to do 30 or 35mph but that the rider was intent on pushing it in a dead straight line no matter what. At this point, neighbors grilling on their decks etc are all stopping what they’re doing and staring ... if that ski was being operated without knowledge of the owner I feel for him / her and, if it wasn’t then, I really feel for the mechanic who’s gonna get it being told, “Gee, it was running all day ...!”
 
Balance shaft on mine sets in a pool of 30# oil which you maintain. Thus, the bearings are not sealed. The bolt on a top view is where the oil is added. I purchased both halves with the counter balance shaft on eBay for about $300.
R
 
Balance shaft on mine sets in a pool of 30# oil which you maintain. Thus, the bearings are not sealed. The bolt on a top view is where the oil is added. I purchased both halves with the counter balance shaft on eBay for about $300.
R

On a 951 the balancer is in oil. This is a 787 and the front bearing is sealed and the rear is lubricated by 2-stroke oil, they aren’t the same.
 
Hmmmmmm Carbs had the high speed adjusters a 1-1/2 turns. I replaced the needles with some better ones set the pop off and put the adjusters where they should be and took it to the water. 40mph. 6400 RPM. Engine is responding well to throttle just isn't making power. Compression is good. I'm thinking the Raves are not opening or the Water Control Valve might be stuck or something. I can't see it being the carbs but I didn't rebuild them so there is a possibility. Test and tune time. :D
 
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Here are some pictures of the engine. Like I said... in the ski when I rotated the crank... I didn't feel anything out of the ordinary. LOL We're gonna have an interesting discussion. :D I gotta find out what they were drinking and get me some. :D D: 1996 GTX Bad Engine (4).JPEG1996 GTX Bad Engine (3).JPEG1996 GTX Bad Engine (2).JPEG1996 GTX Bad Engine (1).JPEG
 
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