Anything I need to know before I replace my front sprocket, or is it a bolt on bolt kind of thing???

Peace
Willfulone

 

One thing is the stock 400EX chain has no master link in it. The easiest way to change it is to just grind out a link and put a new chain on it, but you could loosen up the chain and have enough slack to change the sprocket...that is what I did the first time I changed my front sprocket on my old 400.

If you have ridden on the current chain for a significant amount of time you really should change it. If you don't change all the components, chain, frt and rear sprockets at the same time. The old components will just wear the new component out faster to match the state of wear. So basically your new sprocket will be just as worn out as your back sprocket and chain in a couple of hours.