EDIT: It's been 2 years since I installed this heater and 2 years since I posted this report. I thought I'd share it again with some of the newer guys....
10/15/2011 It's bothered me for a long time: Been told for years that 90% of all engine wear occurs in the first 10 minutes of operation, ( or something like that.)
I really do commute 12 months out of the year down here and I park the bike in an unheated shed. Even in NC it gets cold, 20's and 30's in the morning during winter months is not uncommon.
It always bothers me to start my bike and hear the slower rollover in the motor, with the ticking and mild clacking that happens as the 20W-50 oil tries to get through to all those tiny little spaces Harley designed into the Twin Cam. ( Running Gear Drive cams doesn't help either.)
After 30 seconds or so things quiet down some and she idles for 5 or 6 minutes before I take her gently down the road, watching the oil gauge push 40 lbs at 2300 rpm. It's finally 'warmed up' 20 minutes later, ( almost halfway to work.)
Last week I put an Engine Block Heater on the bottom of the oil sump. The one I found is 4"x 5" and about 1/4" thick. Flexible Hi Temp rubber coated and siliconed to the ribbed bottom of the pan with Hi Temp RTV. Ran the plug and wires up the frame on the right and down the left, hiding the plug under the left side cover near the swingarm.
The heater uses 120 volt outlet power and generates 125 Watts. Way too hot to hold in your hand, but not enough to burn the house down.
I experimented with a timer during our week of high 30 degree weather last week, and borrowed my wife's meat thermometer, ( Thanks Honey!)
Timer turns on at 2:00 a.m. and off at 5:00 a.m. Last week the oil was up to 95 degress at start and Oh(!) what a difference!
Bike starts like it's summertime. There is no ticking /clacking as the oil gets where it needs to go immediatley. I'm on the bike as soon as the fast idle settles down to normal and the oil pressure indicates hot oil ( 8 lbs idle / 32 cruising,) within 10 minutes or so.
I have a smart meter on the house electric meter and can see no significant increase in our daily wattage.
The unit cost me $29 delivered to the house. I found the seller on EBay but bought it direct.