Hello i am in the middle of an FCR conversion on my DR650 and i just happen to be one of the 30% that has a #70 slow air jet stock as opposed to the required #100 now i have one on order through the local yamaha but me being the kinda guy we all are i starting thinking about the actual size of the #70 compared to the #100 and i just happened to have had a very well stocked tip drill set so i grabbed all of my main jets mic'd a drill at 1.6mm and stuffed it through the 160 main mmm mmm pefect fit tried a 145 with a bit mic'd at 1.45mm yet another pefect fit ? coincedance? maybe so i tried a 150 main jet with a 1.5 mm bit, yup perfect fit, so this leads me to think a #70 slow air jet is in fact a .70 mm diameter? what sucks is the smallest tip drill i have is a .79 so in the interest of all things cool i started drilling and the amount that came out on the 1st bore leads to think i am right? i than proceeded to go up until i reached 1.00mm thus maybe a #100 slow jet? i am steps away from reinstalling the carb and trying thisout but i quite honestly don't have a clue on what differance the jet change makes???