What make of carb was fitted to this model .thanks

You've listed two very different models...  but with the exception of a few mini bikes and models of the TY series the carbs were Mikuni.

I assume that the reference to CT3 in the title is a typo?

Have a butchers at the parts list, either on the CMSNL website or the parts list in the Tech Library (see top tool bar) on this forum, and the details are shown there.

If your bike is still running the original 6v electrics, and if a previous owner hasn't done so already, fit a 6v regulator (see the relevant Service Bulletin in the Tech Library). Also make sure that your brake shoes are fairly fresh! 

Thanks its a 72 dt2 250

Why fit a new regulator.
Thanks for the info

These bikes never came with a regulator originally and Yamaha recommended the retro fitting of them, as per the relevant Service Bulletin (see link below). If you don't, then your next question is likely to be "why does my bike keep blowing headlight bulbs?"! 

If you can't find an original Yamaha 6v regulator, then Rex's Speed Shop here in the UK sell universal ones. Make sure that it is grounded to earth.

Vintage Yamaha Enduro Fans - Service Bulletin #M5-084 re Voltage Regulators (yamaha-enduros.com)