Hello, It would be great if someone could help me to choose new jets before ordering my parts from US. (I live in Dubai UAE!) I have a 650 XS special 1978 with Mikuni BS38. I added two XS performance Pod Air Filters (http://www.mikesxs.net/parts/yamaha-xs650-57mm-tapered-oval-pod-air-filter-2-1-4) And two bigger than stock Stainless Steel XS Performance Headpipe Set - 1.75" (45mm.) OD x 1.65" (42mm). (http://www.mikesxs.net/parts/yamaha-xs650-stainless-xs-perf-headpipe-set) With two Lossa reverse cone mufflers (http://www.lossaengineering.com/col...-brand-reverse-cone-muffler?variant=856209431) Main jet: 135 Pilot: 27.5 Don't know if someone has some near conditions in the US (i don't think so!), it could help me to change the jets... The bike is not working well at all like that. Average temp 33°C or 91.4°F (in between 25° and 40° degrees), Average humidity around 40%. Alt: sea level... What will you try? Thanks, MIchel.