Low speed vibration.

[32vickie]

Ski is a JS550 with about 20 hours on engine rebuild.
Ski has a vibration at idle and low speeds. First I thought it was the pump and pulled and replaces bearings, checked pump to impeller clearance. All OK but I replaced the bearings and seals anyway. Repacked everything still has low speed vibration. Rebuild 20 hours ago was complete rebuild with bore of the cylinders new pistons seals and rebuild of the carbs. Vibration seems to be coming from the motor. Tried to rock the motor thinking a motor mount was bad everything seems tight? Ski was plenty of power and top speed is fine. Plugs look light brown in color. Any clues? Idle seems off but was not able to put ski on the hose yesterday to get it up to temperature.

Doug

 

[surfjetlouie]

Ski is a JS550 with about 20 hours on engine rebuild.
Ski has a vibration at idle and low speeds. First I thought it was the pump and pulled and replaces bearings, checked pump to impeller clearance. All OK but I replaced the bearings and seals anyway. Repacked everything still has low speed vibration. Rebuild 20 hours ago was complete rebuild with bore of the cylinders new pistons seals and rebuild of the carbs. Vibration seems to be coming from the motor. Tried to rock the motor thinking a motor mount was bad everything seems tight? Ski was plenty of power and top speed is fine. Plugs look light brown in color. Any clues? Idle seems off but was not able to put ski on the hose yesterday to get it up to temperature.

Doug

did you check the bearing in the bearing box that is agains the firewall?

 

[32vickie]

When i pulled the pump there was no play in the shaft so i thought the mid shaft bearing was OK. I am going to start the motor and look for small air leak? Then i guess pull the pump again. Was hoping to ride it tomorrow.
Doug

 

[sflsurfrider]

what is your method of alligning the engine, pump and driveshaft carrier?

 

[32vickie]

Engine driveshaft and pump were done at a shop. When i did the the pump i just slid it in and put in the same shims.
Doug

 

[Freestyleriverrat]

Engine driveshaft and pump were done at a shop.

Was it a good shop? :haha: You would really be surprised what some shops let walk out their door. That why I don't let many people work on my stuff. Cars are a different story b/c usually a quality shop is good, but PWC and such is a totally different story. Do you know the mechanic?

 

[32vickie]

Work was done at Bucks County Kawasaki. It seemed like they did OK the other ski is fine. Learned to do all of the work myself now. Vibration is less today, put in new plugs, but something is not right. I think the bearings are going? Winter project.
Doug

 

[douglee25]

Work was done at Bucks County Kawasaki. It seemed like they did OK the other ski is fine. Learned to do all of the work myself now. Vibration is less today, put in new plugs, but something is not right. I think the bearings are going? Winter project.
Doug

Did you suck up anything in your pump lately? I did previously and it had a low speed vibration. It turns out the trailing edge was boogered on the prop. Of course you couldn't tell this until the prop was pulled completely off the shaft.

Doug

 

[Shrivel]

In my experience with my 550, a little shake at idle is pretty normal. Hell, I would've started worrying if it didn't rattle...

 

[32vickie]

Well that is the problem i have two. One ski does not rattle and the other does. the low speed vibration can be felt up to about 1/2 throttle. but when it is above 1/2 you can still feel something. Pulled the pump and replaced the bearings, so the prop is clean. Ski ran fine early in the year, now it has this problem. I normally do not ride that ski since my other has a factory pipe and set up a little differently. Vibrations seems to be coming from the front of the motor.
Doug

 

[meatball]

Take a flat ruler and check the alignment on the couplers. The reason it might be less today could be the motor mounts or couplers wearing into the possible uneven alignment.

 

[32vickie]

i will check it out with the ruler and see what happens. What i need to do is to get to NJ and ride some surf with some friends and see what they say. Then buy a Super Jet:Banane01:

Doug

 

[550 SLUT]

i will check it out with the ruler and see what happens. What i need to do is to get to NJ and ride some surf with some friends and see what they say. Then buy a Super Jet:Banane01:

Doug

if u feel the vibration at ur feet u have pump or driveshaft problems
if u feel in your hands motor coupler problems

 

[32vickie]

I feel it in my hands not in the feet. If you put sand on the hood it would vibrate off. So, see it in the hood and feel it in the hands.
And i just had the pump out. is there a way of replacing the coupler without pulling the pump?

I don't think so.

Doug

PS. sand came from the kids throwing it at each other at the beach.

 

[meatball]

You dont need to replace the coupler if is misaligned, if its aligned, its not the coupler.

 

[douglee25]

Just a thought here.... If the vibration wasn't there one day and then it was the next, that leads me to believe it isn't the coupler. That's not to say it isn't though. Nevertheless, I know you said you checked the motor mounts, but did you physically just rock the engine, or did you unbolt each mount and inspect it? The reason why I ask is because I have seen cases where one mount is bad but the other three hold the motor enough to make it appear that its good. The only way to tell is unbolt each one.

Doug

 

[550 SLUT]

vibs

check motors mounts
check coupler alignment
check couplers

 

[32vickie]

No i just tried to rock the motor. I will be checking out each motor mount tomorrow and yes the vibration started in one day. When i unbolt the motor mounts what should I look for, are they like car motor mounts. I will look them up in my repair manual
Thanks for the info.

 

[550 SLUT]

No i just tried to rock the motor. I will be checking out each motor mount tomorrow and yes the vibration started in one day. When i unbolt the motor mounts what should I look for, are they like car motor mounts. I will look them up in my repair manual
Thanks for the info.

if u can move ur motor like back and forth and left and right u need new ones
if u replace them watch out for the shims that are under them
gordy on ebay are the ones u want i think like 60 for all 4