With a wrinkled brow my mind has developed a question. While i accept C4 are a better or upgrade from a C3 bearing in this situation.. yet yamaha and I presume most makers specify C3 for mains . what makes a rotax bottom end any better to warrant the use of C4? I havnt heard of many jap bikes having catastrophic bottom end failures and I assume they would do the same RPM and have the same loads as a rotax. What am i missing?
Horse Power especially when the cases get hot . Many Japanese engines use C4 bearings OEM (Honda RS/Yamaha TZ), C3 are fine for road/trail engines but as soon as you push the envelope the C4 is the only option. The exception is the Aprilia RS 125 road bike (Rotax Type 122/123 engine) will run for less than 100km before the cage shits itself if you put C3's in. Don't ask me how I know that
What makes a Rotax bottom end better, tighter tolerances and far better materials.
C5 were used in the old air cooled 100cc formula A kart engines what revved to 22,000 rpm
