Can you change tranny gears to decrease rpm's on highway? Or maybe change sprockets.

To change gears in tranny would be costly to do.The better option is to put a smaller sproket on rear wheel.But remember that if you make ratio higher you will loose low end takeoff.Such as if rear sprocket is now a 45 tooth and you drop down to a 42 tooth your bike will have more top end and loose a little on bottom end.Your best bet is to go to honda tell them what size sprocket you have on motor and rear wheel and tell them what your looking to improve on,they should give you the best advice on that particular bike since all bikes have differant power ranges.also 1 tooth on front sprocket is eqaul to 5 teeth on rear.there are all differant things that come into play when chaging sprockets,like lenth of chain and how much room on engine to fit sprocket.You can only change so much with stock chain.Thats why you better off checking with honda so this way you dont waste to much time or money.

You can add teeth to the front sprocket or take teeth off of the rear sprocket. In the case of your bike , I do not think there is a 17 tooth front available so your best option would be to shorten your chain and drop from the 44 tooth rear sprocket to 40 tooth or a 36 tooth rear sprocket. That would be like adding one or two teeth to the front sprocket. Your stock is 16/44 so decrease from there. Be sure to ID your chain, get a chain breaker, and a new master link.