Posted by Gordon Maney [76.76.230.60] on Wednesday, September 25, 2013 at 10:50:28 :
In Reply to: Accelerator pump adjustment. posted by Sterling Luttrell [99.58.180.94] on Wednesday, September 25, 2013 at 00:07:14 :
The intent of the alternative stroke lengths is to allow for seasonal change. Examine the linkage and the placement of the pivot holes — you will see that the hole on one end makes the piston stroke the shortest and the hole on the opposite end makes the stroke the longest. A center hole would then be a compromise.
The longest stroke is for winter and the shortest stroke is for summer. Gasoline has reduced volatility — ability to vaporize — at low, winter temperatures, thereby hindering accelerator pump function. Just like the heat riser valve, most people didn't want to mess with them seasonally so they left them in one place. Those leaving such items in one place all year round would typically leave them at the midpoint.