Rumble at high revs

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Can anyone give me a clue as to what might be causing my '07 RXT to make a deep rumble/vibration when running at more than 4000rpm. It happened suddenly today while running at about 80kph (50mph) so I slowed down and fortunately was able to ride it back to the trailer at less than 4000rpm.

While running at low revs all seems to be fine, but as soon as I try to open the throttle it rumbles or vibrates somewhere in the engine or the impeller. I can't tell where. It actually sounds good when its rumbling - a bit like a V8 but there's no way I'll ride it in that condition. I get the impression that somethings going to give way and the engine will just stop and stay stopped!

When I got it home and cleaned it up, it sounded and felt like it normally does with the hose on. There is no evidence of anything tangled in the impeller, or any visible damage.

It's done 81 hours and was last serviced at 50 hours.

Any suggestions for what might be causing this?:(
Problem gone!

Well since no-one out there was able to post a useful reply, I thought I'd give those that are interested some feedback - in case it ever happens to you. :hat:

After giving this some thought, I began to wonder if something had become tangled in the impeller and subsequently blown loose while we were riding back to the car. At the time I wasn't game to give the engine another big rev. I also wasn't keen to take it back to the shop and spend possibly hundreds to find nothing wrong. So I took a bit of a punt and decided to put it back in the water today to make sure if there was a problem or not. And sure enough the RXT ran fine up to full revs. I had it in the water for about 2 hours without a problem.

My theory :redface: now is that we ran over some weed or rope or,.... wait for it....a jelly blubber.

Last weekend there were huge 2 feet long and 18" diameter jelly blubbers in the water. Lots of them. I wonder if one got stuck on the intake grate and blocked the water flow. The rumble I heard might have been cavitation. The animal might not even have got sucked through - it might have fallen off???

Who would have thought it possible???

In any case all is fine and we're heading out again this arvo.:hurray:
Well I would have suggested the dreaded supercharger washers, but if it's cleared then it's probably not!
I did hear of someone who'd had the new washers put on where they broke down and went through the engine, but that may have been related to his k&n air filter...
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