RM250 gearing

I've got a 2005 RM250.I've been running 13-48 (stock is 13-50)and want to go taller.I got a 14 tooth aftermarket countershaft sprocket (to go 14-50,or even 14-49),but the slightly bigger sprocket doesn't want to fit (the countershaft is very close to the swingarm).If I grind a little rubber off the swingarm protector I can get it on,but it still won't move freely (to get it to spin freely,I'd have to put a pretty deep groove in the swingarm pad) I was wondering if anyone had done this modification or had any ideas?The fit is so tight that the stock 13 tooth has a fairly deep groove in the swingarm pad already.Suzuki doesn't mention changing the front sprocket in the manual,only one tooth changes in the rear.

Thanks