The decom valve I blocked 2 holes off didn't solve the problem today, it reduced the kickback to being not too bad. I ended up fitting another decomp valve which had the brass piece in the end of it and that removed all the kicking back. Motor still takes a few pulls to get it started but the owners doesn't want the carby modified so that is his problem. I might fit a modified one just to prove to me that it will solve this problem and then put his original one back.
