*
Are you sure its not a WY or WZ series carb....they have a screw and large washer instead of *the needle on top
Does the screw turn when the throttle is opened.

The wda52 is a bigger carb. *The size of the carb is based on how the engine breathes...from the intake to the exhaust and everything in between.
A wda52 probably has a different size jet on the 400cc than it would on the 440cc
You can try it to see if it starts but tuning it might be difficult.

Heres some info
http://www.vintagesleds.com/library/...-WD-WDA-WR.pdf