The 426 kit just uses the YZ400 D/E model piston. You can bore the F model out and use those pistons, it was a popular mod in the day.
no it doesn't . It is an 85mm bore but not the same piston. I bought Landmans spare OW stuff after he'd finished with the F.
What i'm saying is you can use the D/E YZ400 piston in the F, Gaythorne Yamaha ran them in Andrew Bailey's YZ400F in '79... Ask him
wonder how that worked out for him? I used one one afternoon of practice thinking that it would be better than using up my OW pistons and it was crap, put the OW back in before the next race.F models have 5mm longer stroke and a 7.5mm longer rod. If the bore size of the piston was all that mattered yamaha would have used the old D/E pistons in the IT425G and YZ465's,they dont.
