justin_o_guy2 wrote on 01/19/15 at 07:49:59:


Not at a closed throttle setting for starting the bike.  There is so little air moving through the engine that it doesn't know what kind of filter is on the bike.  The throttle butterfly is almost completely closed, the slide is all the way down....and the motor is cranking over really slowly compared to idle speed.

Air filter and exhaust changes can make a big difference at running speeds, and the stock vacuum petcock can stop functioning at highway speeds when you have a free flowing filter on the bike.  Some folks have experienced their bike shutting off at higher speeds - but then it runs fine at lower throttle settings where the intake vacuum is higher.