Papa Bear wrote on 10/31/16 at 04:28:24:How many years/miles were on your bike when it failed?
Bought new in 2012, started occasional sputtering +800 miles, completely conked out just over 1,000 miles. Turned to PRI to get home. Already had the Yama petcock, as forum members advised (warned) to expect it. About $30, easy fix. I now believe the (GOVT mandated) ethanol in the gas is the culprit, as S40 owners in other countries don't seem to have the problem.
Y'know, Batman, you may be on to something. The sputtering began when under hard acceleration, which causes the manifold vacuum to drop significantly and suddenly. Then roll off the throttle, and the vacuum goes way up again, the engine gets gas again and away she goes. Remember the vacuum-actuated windshield wipers on the Vietnam-era Jeeps? Same thing. Overall, it's just a dumb idea to save lazy people an extra step in the start-up process. After the new petcock, it never happened again.