I completely disassembled and cleaned the carb but my 1986 43F just wont start.
I also added a K&N airbox filter.
Could it be because of the increased airflow?
Do I need to adjust the carb?
Needless to say it was quite cold outside...

Was it running before cleaning?
There's a pretty big list if reason why a bike won't start, we need a place to start before even guessing

thanks for your reply

the problem was, well, embarassingly simple, but strange.
for some reason the float chamber wasnt getting any fuel. the float valve was stuck. after disassembling and reassembling the float valve wasnt stuck anymore... strange

but working now