i havent heard of any probs with the timing chains......just get all the marks lined up and install the link and no probs.....unless a tensioner fails. As for the Mikunis i had to get 1/2 thick spacer plates made at Morse Automatic Precision down on S. High Street because with the DOHC engine the top of the carbs would hit the camshaft covers. This i knew in advance since i stay in touch with Terry Naughtin of Team Hansen Honda....real cool and knowledgeable guy when it comes to the cb450. My next project i hope will be a cb350 since there are tons of parts around for em.