I'm a new member, so please forgive me if this topic has been discussed to death already. I have a 1970 CB450 that I have just got running (or had running), but now it won't turnover. The starter spins, no problem. The chain from the starter to the alternator spins, but it won't "catch". It started as an occasional problem, now it flat won't start. I'm trying to set the timing (thank you MNellis for the comprehensive post), but its quite impossible at the moment.