Def not stock , if you pull the chain in the middle of the rear sprocket and it gives
more than 1/4 inch or more sprocket needs replacing and might as well go with a
kit as the previous good advice suggests

I always take the line with a bike where the maint' history is vague - replace these
major items - chain , sprockets , brakes & tires ... basically the stuff that saves your
life

imo chain and sprocket sets are good from 12 to 16k miles depending on how hard
the bike is ridden... myself I go about 12k and change ..... but it depends on brands
and material used - steel versus alum sprockets etc

my 2 cents

 

46 teeth? Wow...I have never counted? But factory set up is 16 front 43 rear....if previous owner gone +3 on the rear? I wonder what front is? If I have time I'll take off the cover & check?

I wonder what is the real difference if I go back stock? I've been riding this bike for 4 years and love it...I really don't want any significant changes because I'm so used to this bike...

 

Well if the front is anywhere near stock then it should be a wheelie monster. But you need the front number for sure to figure the actual ratio. No telling what they may have done.

There are sites that will figure the differences for you. Used to be one called gearingcommander I think , if its still around, for example.

 

Here ya go
Gearing Commander: Motorcycle Speed, RPM, Chain & Sprockets Calculator

 

Possibly....


Except it seems he's been adjusting for a period of time and have now, reached those marks, so probably still a pretty good indicator....particularly on aluminum sprockets.

In my case, as I ride reasonably hard, the rule of thumb I use is generally I replace 1 front tire to every 2 rear tires and 1 complete chain set to every 3 rear tires. I forever now dub that the "1/2/3 Rule". For me tire wear is more indicative of condition of the relative parts based on use then mear mileage alone.

YMMV Pun intended.