2001 Polaris XC 800 hits 105mph, dies and comes back

I'm having top end trouble. It's like I hit the kill switch, then it comes back at a lower MPH. It just starts back up on the fly around 40 mph.

It only happens on high speed runs on the lake.

A friend told me to clean my VES valves. I watched a couple YouTube videos and I'm pretty sure my 800 doesn't have them. They should be projections above the exhaust pipes on the front of the engine. (Liberty engines?)

The premium setting on the ignition switch does seem to make a difference.

Do any of you have experience with this please?

Thanks,
Bill

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2001 Polaris XC 800 hits 105mph, dies and comes back