If you replace the cam chain and after removing all the necessary bits to get to it including the plugs. Check the tappats first as now is a good time to replace any shims, remove both cams but do not remove the sprockets. there is no need.
This allows you to turn the engine over to feed the new split chain through the tunnel and around the crank without destroying your valves.
Line up the exhaust cam first and then roll the inlet one back in, a little bit of trial and error and frustration if you don't get it right first time.
All cam and crank marks should line up perfectly.
The best way to check if the chain is worn is to see if the timing marks line up. a worn chain can be up to one tooth out in the timing. The timing on my 600 was over one tooth on the exhaust side and the chain was a link and a half longer than the replacement. The tensioner was not at the max but about 5 notches from the end.
