Honda CRF1100AL 2019 Owner's Manual page 303

Other Adjustments Adjusting the Windscreen Height
u
If the windscreen does not move smoothly,
clean the sliders using a sponge or a soft
towel with neutral detergent to remove dust.
Do not apply a lubricant to the sliders.
u
If the windscreen does not move smoothly
after cleaning the sliders, have your vehicle
inspected by your dealer.
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