Ok,so first of all,I'm in port elizabeth sa,also bought a mc16,did a clean up,repaint job onit,38000km on clock,never opened up motor,3rd owner,I experiences the same single cylinder problem as you have,took me a lot of time to determine the problem,which was faulty cdi unit(it takes 2,1 per cylinder)the way to tese is to swop the cdis around and see if the other pipe smokes/fires,you'll emediatly see that only one pipe smokes if it runs on one cyl.I bought a 2nd hand cdi in jhb for r500 and problem solved.other places is r1500 plus vat,ns 2stroke etc.any help or assistance,please contact me,074 606 1122 johan