I've wondered before if one of those coffee mug heaters could be used to warm a motorcycle engine block.
There all over the interwebs at about $15.
Like this one:
![](http://www.acitydiscount.com/pics/std/Alt_Pics/942-5562.jpg)
They run about 18w.
The only thing would be how to temporarily affix it to the block.
On the other hand, it's really not that expensive to run a 100w bulb round the clock.
If you assume 10 cents per kilowatt-hour, and it takes 10 hours burning to equal 1 kWhr, then 0.10 x 24/10 x 31 =
$7.44 per month per 100w bulb burning all the time.
-K