It has a ceramic lined cylinder which has superior heat dissipation properties, not unlike the ceramic panels that were used on the space shuttle for re-entry into the atmosphere...I never took the motor apart to begin with since bicycle-engines.com puts a six month warranty on the entire motor kit to begin with...I figured if anything went wrong, they get to replace it...lol...They did replace a couple of minor items that i didnt think were just right without any problem whatsoever...I also only use their phone to make orders with them as well...Phone number is...(406) 586-5970).
Mine was powerful and fast right out of the box as im sure you have read about here on the forums already...DAMIEN