On Sat, 13 Jun 2009 14:48:32 -0700, "iwdplz"
wrote:

The interesting thing is that all 3 of these engines would run great under
normal load (while cutting grass, while pumping water, while spraying). The
fluctuation only happens at idle or under non-operating load.

Makes me think of fuel / air adjustment, maybe a fine tune of the
screws.