Here's some technical Bulletins relating to the twin, there's some interesting info in here, in particular, there is dates.
From these, we can see that the 500 twin (Orange) was released in 75, and that by 1977 the heat shield, cranks fins and magneto cover had been added, as well as the tap moved, and changes to the carburettor.
From this, and details I have of the history of the G4 & LM carburettors, I can say that it would makes sense to me that NO 500 twins (orange/white) would have originally been fitted with an LM carburettor, further, I have found enough to have me believe that the G4 was never released during it's run (1974-1978) with the white face that includes the primer bulb.
However many will be seen with this face, as changing over was recommended.
Here is the info I have found, I will also be putting up some carby info soon.
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7323-twin1.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7324-twin2.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7325-twin3.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7326-twin4.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7327-twin5.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7328-twin6.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7329-twin7.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7330-twin8.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7331-twin9.jpg)
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7332-twin10.jpg)
I have also found one reference so far to help with dating the Gold Supreme, which I have heard in the past was possibly actually from around 1980.
Here is a snippet from a large, May 1980 bulletein, showing the cowls available for the current range that year.
![[Linked Image]](https://www.outdoorking-forum.com.au/forum/uploads/usergals/2012/08/full-5013-7333-may80.jpg)
Personally, this new info has me keen on collecting 4 different twin cylinder models:
1) The original 1975 Victa 500 Twin, with no modifications.
2) The later (circa 77) Victa 500 Twin, with the modifications.
3) The 1978 Victa Supreme (Green & White)
4) The 1980? Victa Supreme (Gold & Chocolate)