Got an O-ring and from everything I've read it seems they last about the same distance as the engine, about 10k miles, I've had the 520 that I've just take off since I got the bike just over a year ago and I've had to adjust it once! Needed to replace it because I managed to mangle it a bit by resting the engine on it :/ it was ok just a bit rough but now I have money again I wanna get it running properly.Originally Posted by jonnydangerous
The only reason they put a 520 on as standard was because 415 chains aren't what you'd call easy to come by, from what I've read moving down to a 415 makes the bike much more responsive and lively. You have to take into account that unless (*cough* until*cough*) I get the cylinder tuned and get the head machined the bike is only putting out about 23-24 bhp so the strain on the chain isn't what you'd call huge!
Ill give it a go and if it all goes horribly wrong and the chain wears out in no time at all ill swap it back over to a 520.