John - Not sure if you have an enclosed transom? I relocated mine when I rebuilt my transom to under the new transom cap with a oil fill deckplate -
I ordered the remote oil fill/deckplate kit from Yamaha - did not like the cheap black plastic (Perko made for Yamaha) fill.
I have since replaced it with a S.S. flush mount oil fill with a keyless pop-up cap. The Yamaha cap also had the "no spill" lip on it that holds water I drilled some small drain holes in the lip but water still pooled up on top of the cap. That is not good considering that the oil supply system has no water separator. Water in the oil tank could be an unlikely BUT serious problem.
You can see the black Yamaha fill here -
If you look on the port side you can see the oil tank mounted on the inside of the transom -
Mine was originally mounted on top of the port battery box/mount location in the bilge.
The Yamaha deck fill had a small vent hole drilled near the top of the neck to allow the tank to vent - I drilled a small hole in the new S.S. to acheive the same purpose. This hole is at the top of the fill neck just above where the fill hose ends.