So, my chain flew off, front sprocket question...

[SV1786]

as the title reads, went for a ride with friends got off the highway, shifted gears, but clutch wasn't responding, then my friend told me my chain is off. Thanks to a dude with a Harley and some tools that lived in a nearby house, i was back on the road. So i have to replace my chain, and i'd like to know what is the stock sprocket size? and also you can get smaller or bigger sprocket to gain acceleration or top speed. has anyone done this? which one is for accel. which is for top speed? would you recommend it? does it even make a difference on these bikes?