The is a small key on the front sprocket and small keys on the clutch and the small gear on the engine all are fairly easy to get to by using the puller that comes with most engine kits do put a little oil or never seize on the puller threads before you use it as it helps to keep the threads from gauling.
I did a modification to the idler bolt I used the lathe and drilled the bolt out and use a high grade bolt through the idler and can pinch it down so it won't move or loosen up. I also have drilled and taped the idler mount and put in a small bolt or sheet metal screw so the idle mount can't flop over into the spokes. That way I don't have to walk home and drag the bike cussing all the way.
I have a post on the bikes engine total tear down shows all keys and where they are all you need to do is look at it.