Bigger sprocket
 

since my f4 has a 45 teeth sprocket in the back can a 46 or higher fit on the stock chain??

Yep, you can do a 46 easily.

Example:
F4 stock sizes: 16/45 & 108 link chain (manual says 110 but 108 still gives full range for adjusters)
F4i stock sizes: 16/46 & 108 links

So you're good to go up to 46 w/ your chain unless its less than 108 links.

now i can put a f4i sprocket on my f4 right

No, you cannot use an F4i sprocket. The sprocket carriers are different between the two bikes. You need an F4 sprocket to match the F4 sprocket carrier's bolt pattern.

But you *can* use the 46 teeth you were asking about.

ok thanks gotcbr,one more thing since the stock chain is a 525 and if i was to go down to a 520 chain, can the 46 teeth sprocket for a 525 chain work on the 520 chain or at the teeth to big,, and i think im messing up the numbers

If you're going to run a 520 chain, you need the 520 sprocket.

No, keep them all the same. The drive train is too important to try to short-cut.
If you change the pitch, change them all to that size.

Ern

^ I thought I was clear on that above. ;-)

haha u were, just thought i would ask, since im thinking bout going down 1 up front and up 2 n the back

Check the post times, GotCbr. I was composing whilst you were posting. ;-)

Ern