HI, I have an upgraded Rotax max to Evo engine. The upgrade is full. I changed even the new evo con rod. The upgrade is with the 2015 electricals I have a problem for a few months in very low rpm. 5500 to 7000 approximately. In these rpm I experience a lag (delay) of response. the motor in nearly dead at these rpm. After 7100 I feel that it is starting pushing and gets alive. I have made a lot of carb setups I have even changed a carb that is working in another motor for sure, but no luck. The engine after 7000 rpm is Ok Can anyone help? Please help. I didn't find the right solution from the Internet. References: http://www.karting1.co.uk/forum/viewtopic.php?t=19447&sid=d32b6f77403b8c67b1101f90d4ef3bef Promotional video production agency Thanks!