I have a 98 yz 250 that is has a 14t in the front and 48t out back and the bike has no top end 4 and 5 have no power, are those sprokets part of my problem or should i be looking else where.
Do you have a way of checking the compression? Needing a new top end would cause this. The sprocket combo you are running should give you alot of top end.
You can always buy a 13T front sprocket fairly cheap and see what it does.