It is, most definitely, a Bartel BM-4b.
WINGS PALETTE - Bartel BM-4/BM-5 - Afghanistan
I'm going to be k.o. soon (the Guinness was reeeeally good, David... even better than the strawberries...
) and will spend tomorrow at work, so OH please
if correct
Best regards,
HP
Edit: Wikipedia states that the "b" variant (can be recognized from lower exhaust pipe in the airwar.ru comparative table) is powered by a Walter Vega 5 cylinder, 85 hp. I initially thought that your silence regarding Reg's answer was to be interpreted as tacit consent, but then noticed a familiar nose shape while browsing aviastar...