Well yg1 same as the G7s really .. go on you tube look up (80mph fizzy the banned ones)
That’s me and stow thrashing the hills of lake county FL 10 or so years ago
See here a G7s motor or a yg1 same thing .. we put 20mm tubes in and 20mm carbs .. they almost fit under the cover but not all the way .. note the hole :) so later we put 1979 YZ 80 cylinders and heads on and blacked off the rotory and had 30mm carbs pic to follow
Over 85mph at that point ..
Off to bed lads it’s almost 9 and I’m off on the road 4.45am