Jet history?

[chrisg]

Hi, I notice that when the 350lc first came out it had a 160 main jet. They moved the jet up to 220 the following year. Is there any advantage in upping the jet size on the early model or did they modify anything else requiring the bigger jets ?

Just wondered if the early bikes ran too lean.

[rigga]

First bikes had running issues, Yamaha sent out a service bulletin to dealers, to modify the carbs, and change the jetting, hence the size difference, early non modded carbs (if any left) should be on earlier settings, later modded carbs on the larger jets

[chrisg]

Thanks, I thought that may be the case.