BHP is the horsepower measured at the BREAK (hence the b before HP). Basically, where the crank comes outa the engine to connect to clutch/trans. WHP (be it front or rear, in the case of bikes, rear) is the measured HP that the wheel puts to the ground. The WHP is less then the BHP do to the inefficiancy of the trans/other parts. 2 strokers are deffinatly more powerful than the 4 stroker kin. For example, a 4 stroke Kawa KX250F makes 43 BHP. The Kawa KX250 (2 stroker) makes 56 BHP. That's a 13 BHP increase! And another thing about a 2 stroekr, their power is generally "all there" at a twist of the throttle, where as a 4 stroker needs to actually rev up to make it's power. Now, a 250 road bike isn't going to make 43 BHP, more like the 30ish that was stated, it's just that it's easier to compare this way. It'd be pointless to compare a 2 stroke to a typical road bike sense the 2 stroker is generally in a "race" version of a bike (well, dirt bikes). For example, a kawa KLX 300R makes 33 BHP, less than the KX250F. Perfect example of a high-strung race prepped motor. Even a Kawa KLE 500 street bike makes less BHP than the KX250 (48 BHP). Now, the KX125 (2 stroker) makes 39.7 BHP (Almost as much as the KX 250F! From HALF the displacement). A big part is comparing two like bikes. Can't do the entry level 125 learner bike against a race prepped 125 2 stroker monster. Be the learner a 2 stroker or 4. But yes, a 125 2 stroker is just as or even more powerful than the equivalent 250 four stroker. Just as a 250 2 stroker can be more powerful than those big thumper enduros (KLR650, "only" 33 BHP).
I hope that isn't too much all at once to let soak in. It woulda sounded a little less confusing if spoken/could ask questions while explaining. But hey, i love explaining thisngs like this, so please, ask away
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PS - Is this your bike?:
http://www.bikez.com/bike/index.php?bike=18428 if it is, you're a little over 14.6 BHP
(Another example of 2 stroke vs 4 stroke, that 125 road prepped bike is as powerfull as my 200CC 4 stroke dirt bike.)
Another PS -
http://science.howstuffworks.com/two-stroke.htm HowStuffWorks article on how 2 strokes work
http://science.howstuffworks.com/engine.htm HowStuffWorks article on car engines (4 strokes, same basic principal as a moto engine.)
Maths never was my strong point!