Join Date: Oct 2018
Location: Prescott, Wi. Upper Ms.River bluff country
Looking thru my 2017 service manual, there doesn't seem to be any method of horizontal adjustment or run-out spec for the throttle grip. Mine has about 2~mm horizontal play as well. The rubber grip rides on an inner sleeve that appears to hold the grip in place by a retaining ring(s) of some sort, which is not visible. The drawings & photos don't show any detail of the parts involved for the grip itself.
Kind of a long way around, but maybe you could go to a Suzuki Dealer and check out the play on a new bike to see if perhaps yours is wearing out. There may be a Technical Service Bulletin (TSB) covering this as well.
"It is amazing what you can accomplish if you are not concerned with who gets the credit"- Patrick Griffin
18 wheels move the cargo, 4 wheels move the body, 2 wheels move the soul -unknown
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I visited the Air & Space Museum- didn't see a thing...