Kawasaki KX100
KTM 105 SX
Honda CRF150R
Let's face it: The biggest of minicycles are in a weird place. The Honda CRF150R, Kawasaki KX100 and KTM 105 SX sell well, or at least in numbers that justify their existence, and each receives all the full-race attention of its race-dedicated siblings in the 85cc classes, but as a racer it can be very difficult to own just one of these three bikes. There are hugely competitive classes for superminis at any large amateur race, but many local races don't have a class and don't allow them to race with minis. Perhaps we, like the owners of these excellent machines, should concentrate on what these bikes are, rather than what they are not.
Big-wheels or superminis can have varying displacements, but the outside for two-strokes for production is 105cc, though many race organizations allow 112cc. For the lone four-stroke, 150cc is production and the race limit. Each of these bikes has a 16-inch rear wheel and a 19-inch front. All share many if not all major parts in common with 85cc MXers. As a result superminis have the light weight and nimble handling of an 85 with more stability, wheels that roll over bumps easier and engines that are generally blessed with added torque and are easier to ride than an 85. Superminis offer all this goodness at the cost of a few pounds and some extra seat height. They are also the only stepping stone between minis and full-size motorcycles, so more of these machines end up on trails than on tracks. For 2010, three models are readily available, and each is a very different animal. Because of the wide range of riders these bikes appeal to, we selected a rider group consisting of a young KX85 racer and sometime trail kid just contemplating a supermini, a petite woman CRF150R weekend warrior (off-road and on tracks), and an aggressive racer who has just moved up to big bikes but still has the physical size to be at home on these models.
Honda CRF150R
In a class of motorcycles that hardly have a niche, the CRF150R is the odd one in a group of odd ones. It is the only four-stroke in the class. It doesn't share many parts with the larger CRFs but is identical in engine concept, though it has a steel-tube frame that the larger CR/CRFs haven't used for over a decade. In other words, the engine is a high-performance short-stroke four-valve design using the Honda Unicam single cam. It revs high and fast with very little vibration compared to the two-strokes. On the track it pulls hard, but not really harder than the two-strokes (especially the KTM). The advantage it has is a wide span of usable rpm, so the engine is more forgiving in questionable traction than the pingers. It isn't anything like a traditional trailbike four-stroke engine, though. It doesn't have a lot of grunt or torque, and like the two-strokes, it takes a lot of clutch and rpm to get it moving. It has good throttle control and clean response at small throttle opening, but the two-strokes snap to life and crack out of turns with more life. Get the engine spinning hard and the Honda hauls. The engine is at its best on hard, slippery surfaces where the tractability pays off.
Despite the four-stroke engine, the weight penalty is minor, but the tall engine carries weight higher in the frame, and the lighter the rider, the more the rider feels that the CRF is heavy. Other than that trait, the chassis is very nice with a good solid feel and very little flex and equipped with quality suspension components and settings.