Oil Tank Inspection Window.....Which Way Is Up??

[Steve S.]

I went to install my oil tank window and noticed when I turned it over there is one hole that is oval shaped, not round like the others. 
Anyone know which direction the oval shaped hole goes to?  Or does it even matter?  Thanks!

Steve S.

[BRT-GTR]

Steve S,
            Knowing BS that extended hole will be there for a reason, I've just levered a ruined one out of my resto bike and YES the wider hole is at the BOTTOM. No doubt it assists the oil to run in and out , to ensure you can clearly see the level has dropped below the window.
I thought I did  have a one good tank window but can now see it is all crazed and has probably got a hole in it. Oh well add it to the parts list.
Regards, Brian the Brit.

[Steve S.]

BRT-GTR,
You're explanation does make sense.  I will put the oval hole at the bottom.  I thought there had to be a reason.  Thanks for your reply!

Steve S.

[ziggy stardust]

I replaced mine just the other day, elongated hole at the bottom and the BS on the outside at the top.
Z

[BRT-GTR]

Hi All.
         Had a better look at my tank window. They come apart very easily, back simply eases out with your finger nails and then front can be pushed/eased out to the front. The window damage is on the outside only of the 'glass', inside is perfect,  some cretin has used cellulose thinners to attack it, I think. There goes 20 GBP.  The red pip is actually moulded into the window but if cut off would sit in its recess on the back plate. Will try to find some suitable plastic and have a go at making a new window ( YEP, CHEAPSKATE ) but might work. Save some of those OEM windows for future concours restorers.
 Brian the Brit.