OK I'll pull it apart again tomorrow and get my vernier gauge on it and see if I can find something suitable.

I have had another strip down and here's some photos. The pipe was slightly bent and when I straightened it the other day I thought I'd done a lot more damage than it appears now I have inspected it properly. It has a small crack from one of the holes that runs about 90 degrees around the pipe, its not at all loose so I'm wondering if I actually need to repair this as there factory drilled holes in the pipe, two at the bottom & two at the top, would the addition of this small crack make a difference? Or are these holes (and the size of them) critical to the cold start assembly?
imgur.com/a/SXTsEgX    
imgur.com/a/g4YR4Jh

I'd either leave it or try to solder it so crack doesn't grow.

If you can get the bike to start cold, the "choke" system is working good enough.  I wouldn't worry about it.  

Yes I think youre right, I’ll drop a bit of solder on there and leave it at that. 

Hi Gate88,

I too am resurrecting a 74 GT(80)MX I've had for 40+ years, and I'm curious about the markings on your carb and oil pump, if your pump is still accessible.

THE CARB
Somewhere in my research I read the original 73 and/or 74 GT carbs should be marked 367E1 on a little pad on the choke side of the upper carb body. However, my carb is marked 367E3 which has me wondering if my carb is original to the bike.

Can you tell me what identification is shown on your OEM Carb?

THE OIL PUMP
I've also read about color coded oil pumps. As I understand it, the pumps of various models were color coded with paint on one of the end cover screws to identify proper fitment on different models.


I've never seen a color code listing that included the 73/74 GT80 or GTMX; nor have I ever seen pink shown in any of the color code listings. The color on my pump sure looks like pink.

What color, if any, is painted on your oil pump cover screw?

Thanks much for your help and good luck with your project!
ZT

Both "pink" and 367E3 are correct for a 1974 GT80A
 

Thanks Mark!