your english dont seem to be bad but if you need some help with translation feel free to PM me what you need translated and i will try to help out :)
but like others have pointed to in this thread i suspect your problem is not enough pumpshot or secondarys opening to quick creating a leancondition that makes the engine backfire thru the carbs.the carbs seem alitle small but i doubt the size of the carbs are the problem.
does the engine run good if you bring it up into higher rpms slowly?
