The introduction of the "F" model in 1979 saw, finally, effective and much anticipated improvements to the now 3 year old TZ 350 C/D/E. Much to the relief of Yamaha devotees, the factory made several changes to the bike, some advantageous, in time owners learnt others were not. They included:

a) The provision of a new "6 port" cylinder, with subsequent improvement in rideability, with an improvement in peak power output to boot. Also new "cross-over" style chambers to keep the muffler tips within FIM requirements length wise and a new piston. The "F" pistons were the first of the short pin "slipper" type but the side windows didn’t have the support web running down the middle, and the ring sometimes pulled the edge of the piston down into the window.

b) A new conrod, which was lighter, but turned out to be prone to failure ( due mainly legend has it, to the wrong silicon content in the pistons causing them to wear and deposit aluminium on the small end bearings causing them to fail and take the conrod with them ), plus a new "3G3" piston to suit the new cylinder.

c) The inclusion of 38mm "Powerjet" Mikuni carburettors to further enhance the new engine's usability through the ability to fine-tune the midrange mixture more effectively and also reduce the risk of seizure at high rpm, while actually contributing to the increase in peak output at the same time.

d) A new, revised, lighter weight frame, which had a bad tendency to fail around the headstock, which is why so many of them were re-inforced in this area, or had aftermarket frames replacing the Yamaha items. (Click here to read about aftermarket TZ frames.)