Final report:
Turns out dirt/mud got into the clutches and was not letting them engage completely, so the belt was slipping.

I'm wondering how the mud got there though, I have not had it deep enough to have water up to the CVT intake, so I'm left with two possibilities, in my mind.

1) The mud got in through the intake from pressure washing the seats and such.
or
2) There is a bad seal/leak somewhere letting dirt into the clutches.

Really hoping it was option 1 as that is easy to solve

[2015 Z Force 800 53/Trail EPS]

Time will tell. No other seal other then the one on the cover ( plus the tubes) so just keep the pressure washer away from the intake grill and you should be OK...if that's all it is.

The CVT exhaust is very low, under the park break. Mud can get in there very easily.

The CVT exhaust is very low, under the park break. Mud can get in there very easily.

Yeah, I'm almost hoping that I accidentally took it too deep and that's how the water got in, because that would mean there's no leak. I see that you have your CVT exhaust raised, how did you go about doing that?

Check that the ducts are not deformed where the rubber boots are. I had this and it let in all sorts of junk.

I used the original rubber part that clamps to the case, but I turned it upward. Then I used some rubber couplers and pieces of 3" plastic pipe that I took off my old Grizzly when I snorkeled it. I used aluminum foil to shield it from the heat and bailing wire to pull it away from the exhaust. I ran it up just under the intake. It was just temporary. I just put on snorkels. I used metal pipe for them. When I took off the old part, it had some heat damage, but was still functional.