 Popular combinations have been Honda RS125 frames with Honda CR85 engine, Yamaha TZ125 frames with Yamaha YZ85 engine, Moriwaki GP80 race bikes, Honda/Jiangshe 185 cc engine in a variety of frames and water-cooled 4 strokes such as the Honda CRF150 and CBR150.The commonly sought after horsepower figures to be competitive are 28 hp for a two-stroke or about 25 hp for a four-stroke.In New Zealand the rules have developed slightly different classing of bikes with the maximum engine size in Formula 4; two strokes up to 100 cc water-cooled or 125 cc air-cooled and 4-strokes up to 150 cc water-cooled and Formula 5; 50 cc 2-strokes and 100 cc 4-strokes.