Super Jet Rebuilt motor making weird sound

[kawa js550]

I just rebuilt my 61x/62T motor this winter with new pistons, crank, seals, and gaskets. Before I rebuilt it, a shop said that one of my crank bearings was bad because it was making a loud rolling noise. I just took the ski out today with the new motor and if I get around to 3/4 throttle I hear it again.... I would go faster to see if it does it at wide open, but I am in the process of breaking in the motor rn. Could the cases be causing this noise? That's pretty much the only thing that hasn't been replaced.

 

[KMN]

So did you get a new crank with old bearings? Where did you get the crank from?

 

[kawa js550]

So did you get a new crank with old bearings? Where did you get the crank from?

Rebuilt crank from sbt

 

[KMN]

Is your motor and pump properly aligned? That could cause some noise if not. I wouldn't install a new crank of one of the bearings was making noise. Does it make that same noise on the trailer? How about if you pull the plugs and just turn it over, noise?

 

[kawa js550]

Is your motor and pump properly aligned? That could cause some noise if not. I wouldn't install a new crank of one of the bearings was making noise. Does it make that same noise on the trailer? How about if you pull the plugs and just turn it over, noise?

The only time I will hear it is if its in the water and going around 3/4 throttle. Maybe im hearing the mid shaft or the pump, but everything is aligned to my knowledge. It doesn't do it on land or if the plugs are pulled, so now im thinking its the pump or midshaft

 

[khaos]

Rebuilt crank from sbt

There you go.

 

[kawa js550]

Oh well looks like im going to have to get use to that noise

 

[codyadams209]

Oh well looks like im going to have to get use to that noise

It's okay you'll only have to listen to it for a little while, that sbt crank won't last too long


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[khaos]

Just ride that poop till it breaks. I know one guy who's had an SBT motor for a few years and it is still going strong. Maybe, this will be #2. I mean its already in and its summertime. Get the thing wet.

That aside none of this is meant to be a slam. Simple stuff gets us when we get frustrated.

Are motor mounts tight? Are they good? Is the gas poop? Low octane gas esp ethanol gas that is old is harder to ignite and can 'act' like the timing is retarding. Pop the head or a plug and get look in the jug for ugly. Ride it flat for 5-10 minutes keep the water out and afterwards check for excessive heat on the coupler. See if the rubber is super squishy/gummy. Are the plugs resistor type? Replace them with new or non for testing, that carbon gets a crack in it and the suck starts. Are they the right plugs? plug# not match the box#? (that one was earned on a box of 8) Are both pistons from the same company @ the same type? (We do things here in junkie country we are not proud of just to ride) Are they installed facing forward. (prolly, it would run like poop before 3/4 throttle if that was the case.)

It could just be the crank is out of balance.

 

[Scraggly]

It's okay you'll only have to listen to it for a little while, that sbt crank won't last too long


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learned that lesson hard way. i got about 20 seconds out of the one and only sbt crank ill ever run

 

[smoofers]

I've got SBT cranks in all three of my skis. Two of them have been running strong for 5 years (SJ and HX). The HX was raced for 3 seasons on the SBT crank and at this point has a couple hundred hours or more on it. If they were such garbage why would Jetmaniac sell so many of them?

 

[Scraggly]

not saying they all are, ive known of plenty run for a long time. i just got a junk one out of the box and trashed a brand new rebuild