Seems to be a bit of difference in terms still so humour me so I know we are communicating correctly.
Choke on equals butterfly closed, restricts airflow from aircleaner side into carb
Choke off equals butterfly open, no restrictions in carb except throttle slide.
Is that your understanding.
So are you finding that the choke needs to be almost closed for the bike to run properly at any rpm? Or just to accelerate from idle.
Does it run ok at idle, does it run ok at riding engine speed.
What are you referring to as a flapper.
Have you had a chance to confirm compression pressure.
Can you post a picture of your carb.
Sorry it is a bit long just trying to get all the issues straight in my head.
You know what that's like at the moment.
On the carb Ive got, when u push the lever down the butterfly opens; this i believe is choke on no airflow restrictions except throttle slide. theres a middle position where the butterfly is at a 45 degree angle, and a closed position which i believe is choke off and when i switch it to that position it dies. if i hold it between the 45 degree position and the closed position it will run and drop the idle, but as soon as i let go it closes and dies. this is on a brand new oem keihin carb im not home right now so i cant take a picture but i will post one later. if when the butterfly is closed that is in fact choke on than im an idiot lol but i dont think thats the case with this carb... but ive been wrong before. the bike runs completely fine and i can tune the idle to a seemingly normal idle with that butterfly wide or at a 45 degree angle but as soon as its closed its dead. and i cant start it with it closed hot or cold which continues to baffle me as this is a new carb so nothing is plugged up. also i dont have a 16mm compression adapter so i havent done a compression test. very difficult to kick by hand and kicks firm when i start it, hot or cold. feels just like my friends crf100, thats why i got it because they are allegedly built like tanks.