Quote:
Originally Posted by Ariel Red Hunter
An overhead cam engine. Hmm. there are trade-offs, as always. Engine is almost always taller. (Except certain weird designs, like the face-cam Chater-Lea). Very difficult to make as light as a push-rod job. If it is a chain drive, should have a 50% reduction to the chain. That way the chain runs at half of engine speed. For a racing engine, with the best parts obtainable, built virtually without regard to cost, taking the reduction in the chain drive system is acceptable because of less weight. We now live in the age of total mass-production. So an engine is now designed for a purpose, not just as a lightweight, junior, or senior class. Road bikes are the most popular class. So an engine is usually designed for a roadster, where acceleration and top speed is very important, especially in the lightweight class (250cc). Then, if the powers that be decide an enduro/dual sport is required to fill out the line, it should be no surprise that they look at the engine they are already building, for reasons of cost control. Perhaps they design a more tractable cam and fit a smaller carburetor. But the porting stays the same, which is really too big for an off-road bike engine. Of course, when cost is no object, then we have bikes like the KTM.
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Good points and it has to do with riding need and preference.
The absolute beauty of the CG motor, both balanced and unbalanced, is that it's built to be bullet proof under the worst conditions possible. It's all about simplicity, ease of repair and long term reliability. Thanks to the pushrods, it does have a really nice mid-range that's a very useful, utilitarian powerband. It also sips gas. Another plus.
For instance, my neighbor has ridden my Q multiple times now. Granted, it's just a 200cc but it's an OHC Suzuki-type motor, a real Mikuni CV carb and it develops much more top end than the TT, even modified. I have it geared longer legged because the top end will pull the higher speeds. Q can pull 70 mph. Ridiculous for a little 200cc bike.
Then he rode the TT... His quote was "This is exactly what I'm looking for in a 250. More torque and useable power for our hills, dirt roads and curves." He really liked the power band and the friendly attitude of the CG motor.
These motors, while mod-able to get their true potential, need to be seen as what they really are. Simple, low maintenance, with long term reliability and user friendly power...that can haul your family of three and a goat to slaughter....on very little fuel.