[Christ]

If you have a very shallow dipstick hole, just stick a crap thermometer in there for a min, and see what it comes up to. Better yet, check how fast the temp rises, so you can gauge how much of your 1.4Kw you're actually getting heat from, versus how much is just dissipating. For something as small as a bike engine, I'd assume you're losing alot of that heat to the open air.

Maybe pull the heater apart and mount the inductive coil element inside the block, or at least wrapped around the block? (Not sure if you need the paint stripper for a paint stripper...)