Ok so simeone on here suggested engine issues.
So im thinking sure why not.
Well i used to tune my aunt's old beach twin . at night no tools but i had a flashlight so warm at idle both set to same rpm you could varify it i discovered by accident looking thru the blades then tune to match. Well ive noticed something about a drine i had i suspected had an intermittent rpm issue so at night all four idling i ask you this while at idle with flashlight looking thru blades would not the "A" turn same rpm at idle and same with "B"?