Is my IMS tank vacuum supposed to compress?

Is this vacuum and distortion normal?

I just installed the 4.7 gallon IMS tank. After riding for an hour or so, the tank distorts. The video below was taken at the gas station, while opening the gas cap. You can visibly see the tank expand once the pressure is released.

Can't really see on the video but I would check that the vent tube is clear. Should be able to blow into the tube you have in the steering stem when the cap is removed. If it was a carby model, you would have stopped long ago.

I have the same tank and have had no such issues.

It seems obvious that something is not venting as it should.

I wonder if the vent cap or the tube is plugged. Do a test! If it got a gush of air when you removed the cap at least you know where the issue is.


Great range with that tank by the way.

Thanks for the reply @drbike. I had the vent tubing incorrectly configured. I reconfigured so the gas cap vent line distributes to the outside air and the lower tank line is attached to the IMS supplied "T" on the throttle body line. All is well now.