The trim assembly is very similar to an OMC trim assembly, I believe it is a Showa trim. On John/Rude motors we use a different type tool than Spanky listed. I've tried those and it is almost impossible to put enough downward pressure to hold the spanner in place while trying to turn the cap. I had a friend who worked in the OMC plant make me a tool for the Yamaha trim caps it is a 4 pin device that slips over the trim ram.
And use this crowfoot style for the tilt ram.