A long stoke engine will develop more torque at lower rpms then a short stroke engine. Though a short stroke will rev faster and accelerate faster.
Or not.
"Lugging" is applying power (opening the throttle) at a combination of load & speed which causes the crankshaft rotation to dramatically slow down nearing TDC. Since the local oil pressure (at the journal) is developed by the speed of the journal passing across the bearing surface, it drops as the crank slows.
Obviously, light throttle at very low RPM is harmless - how else can you leave a stop?
This is also greatly affected by flywheel weight; a 60 lb. wheel allows much more violent acceleration from low speed than a 30 lb. wheel because the crankshaft speed is more nearly regular.
