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Discussion Starter #1
So I have a 2006 VX 110 delux that developed a rough vibration ( a violent shaking of the whole jetski) while i was riding it. It happend at about 50 mph and once I felt it I killed the engine, checked out the grate to see if anything was in it, and it was fine. fired it back up and it idled fine once i got on the throttle and accelerated the vibrating came back. I'm a good mechanic, just new to the pwc's so i was hoping somebody could help me in the direction of a fix :)

Thanks.
 

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Discussion Starter #4
an update... the severe vibration happens only when the jet skii is in the water. it idles and throttles fine out of water (on the trailer)
 

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So I have a 2006 VX 110 delux that developed a rough vibration ( a violent shaking of the whole jetski) while i was riding it. It happend at about 50 mph and once I felt it I killed the engine, checked out the grate to see if anything was in it, and it was fine. fired it back up and it idled fine once i got on the throttle and accelerated the vibrating came back. I'm a good mechanic, just new to the pwc's so i was hoping somebody could help me in the direction of a fix :)

Thanks.
Look again and be EXTRA sure you dont have a little piece of wood or rock nestled up in there.
and
Grab a hod of your engine with both arms and try and rock the engine to see if you got busted motormounts
 

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If the motor mounts are good, I'd agree with Don Long.........probably something in the pump. It could be very small. I had a small piece of plastic bag in there once that made mine vibrate like crazy. You may have to remove the intake grate to see. It is also possible to have a small ding in the impeller that would imbalance it enough to cause vibration.

One other thought is a fouled spark plug. I've seen 1 fouled plug do very weird things on these skis include causing vibration, and you often will not see the problem except at higher rpms. My general rule of thumb is to replace the plugs on any Yamaha 4 stroke at the first sign of any problem, since this is so common on these skis.
 

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I had this same issue the other day, I could not go over 8mph without the ski virating so bad you would not give it any more power.
I drove back to ramp about 10 miles on "no wake mode" really sucked. take it out of the water, and I could see a small stick stuck in the impeller, I took the intake grate off and got the stick out, but have not tested it in the water again yet, I only hope it is ok now.
I really thought because of the vibration that the ski was badly broke maybe a bearing shot or something nuts like that, but no a small stick, go figure.

I think I had this same thing happen with my older ski and small plastic bag once, but I had forgotten all about that at the time, now that I know this I would be more apt to try to get the ski on teh sand and take the grate off and check it out on the water I guess.
 

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Any solutions available for the initial problem, I do have exact the same. Changed the sparkplugs, Jet Pump bearing, complete Midshaft bearing unit. It happens only in the water and the ski runs to topspeed if requested. It’s vibration comes with a high noise as if a motorcycle is at 14000 rpm.
Fair enough to say the VX110 2012 is @ 1080 hours.

I am really frustrated, next bearing will be in the reduction drive gear. Any suggestions ?
 

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Discussion Starter #9
Pitting/ cavitation in the pump casting and impeller caused the vibration. We took the impeller off and polished it as well as the housing. I spent some time going through the grits and ended with a mirror finish. If your housing or impeller has some serious holes its time to replace it. The wear on ours was minor and we were able to refurbish it.

After the repair the vibration is gone and it picks up out of the water a lot smoother and faster!

I wanted to leave this information here in case someone else could use it. So if your housing has a bunch of pits, scratches or is generally rough this might be a place to start after all the pump is designed to push water, not water and air.

Good luck!
 

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If you do find it to be cavitation. Witch will show as a dull line on the impeller with pitting in it. (See pic1) this can be along the outer edge of the impeller as in the picture, or down deep in the root of the blade. It's known as a cavitation burns. This will usually show on all three blades.
Check the clearance between the impeller and wear ring. .018 is the max clearance. Around that Clearance width cavitation will occur. It can also occur if air is infiltrating. This will usually be along the joint between the intake grate and pump. (See pic2).

If the clearance is below .018. and burns are present then air is probably the cause. I'd replace the impeller this will tighten the clearance and install a grate/shoe seal kit and you should be good to go.
Pic 3 is a seal kit from Riva racing. The kit fills air gaps on the back of the intake grate. Use 100% silicone adhesive caulk to glue the pieces of the kit into the grate. Then seal the grate along the green lines from pic2. Sealing both sides along the bolt flange and a crossed the back where it fits to the pump face. Seal this with more of the silicone caulk.
 

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