Super Jet 61X Engine Vibration Dry Pipe with Video

[edomund]

Is this much vibration normal? I've read that dry pipes shake, but this seems like a lot.
The video is a pretty good representation of how much it shakes it's not exagerating it at all.

I pulled the mid shaft and ran the motor with no mid shaft connected to make sure it wasn't my alignment and it shakes exactly the same.
This is a fully rebuilt motor because I thought it was the crank that was vibrating before. It has a rebuilt & trued crank, rebuilt top end and # zero light flywheel, so it's not any of those things causing it. Only thing left I can think of is the pipe. I'm stumpped on what to do next.

Thanks in advance,
Ed

 

[edomund]

I tried pulling the exhaust chamber and starting it to eliminate the pipe causing the issue and I still had the vibration.
I tried a friends known good electronics (stator, cdi,).

Anyone have any ideas of causes?

 

[kevbo]

If you think thats bad check out an SXR engine. Looks normal to me.

 

[edomund]

Yeah the video I don't think lets you see how bad it is, since the frame rate of my camera is so slow. The motor buzzzzzzzez when you rev it up. I had a friend who has a couple 701s look at it and he thinks its vibrating too much. We swapped out essentially every part and still have the problem. I dont see how it could still vibrate with a rebuilt crank and fresh top end.

 

[edomund]

I put my stock 650 mani and pipe on & the vibration was significantly reduced. Do all dry pipes do this or is this 1 messed up?

 

[kevbo]

All engines of this type do, it has most to do with the size of the engine. The bigger they are the more they shake. 650s are noticeably smoother than anything larger. The Yamaha 800 needed a 40lb exhaust for mass dampening and the Seadoo 800-950 use internal balance shafts.