Yamaha pw led display speedometer glitches

Hey, since my hiabike hard nine 4 came bake from repairs I've been having trouble with the sperdometer on the led display. The speed isn't always incorect, but it keeps shifting up and down from the correct speen down to some lower number and back up which is synchronized with the motor and gives the bike a bit of a boost when it goes down. Is there any way to reset the computer to possibly fix this issue?
 
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