Choke issue vm28

[RD350NL]

The choke circuit on my vm28's aircooled rd350 is not functioning properly. At cold start the choke on or off has only a limited impact on the rpm and the bike runs bad/ way too lean the first mile. The choke does do 'something' but just not enough.
 I put a different carb set on and there the issue is not happening so its definitely carb related.

 someone have an idea of manual to follow up diagnosing the problem?

Thanks

[m in sc]

swap the bowls left to right. only the left one is drilled to pass fuel. you shouldn't need to  run the choke while actually riding, only on warm up.  should be off before taking off.