Complex sentence: The clutch plates were also from the NR750 and much larger in diameter than the ones used in the RC30, the first gear was so tall that the increase in clutch plate diameter improved their longevity.
Split into simpler sentences: The clutch plates were also from the NR750 and were much larger in diameter compared to the ones used in the RC30. The first gear was so tall that the increase in clutch plate diameter improved their longevity.