I'm with Matt on that, the rubber tube is basically stationary , so as long as it isn't cracked or brittle....Why change it .
How slack is the primary chain and how slack was the camchain when you removed it? If you suspect you could use a new one of either, get both new. If you are adding more horse power to the engine and you already have a swinging primary or a slack cam chain now's the time to do it.
Why do people turn engines over if they aren't going to split the cases? Because the pan is off only makes this a little better, below your clutch , on the flat spot under the kickstart shaft, the pockets that are just under the crank, the drain plugs that are still in..... all the wasted particles from your clutch and other engine wear lay in these areas , now by turning the case over all that stuff will be infecting the crank bearings,and primary bearings, now it's free to get into all the bearings, backfeed to the oil pump and get all over the gears .... Well , anyways I hope that if your chains look slack that you would consider splitting the cases , clean it all out real good, spill some oil on everything and change out the chains.
Dirt and other particles on the bottom of an engine should either be left at the bottom or cleaned out, never allowed to re infect the motor
