The plug I'm using is a Rossi C6, ( the plug that came with the motor) and which is also the one that is recommended to be used for the 160 by MVVS. As far as I know it is a cold plug for use with nitro. ( see http://www.scootworks.com/rdrc/gloplugs.html ) I use my own mix of 5% nitro, 10% cool power, 5% caster oil. Also using a 18x8 wooden prop. As far as I know my motor has the roller bearings on the conrod, because thats what the exploded view shows on the documentation that came with the motor. Although I hav'nt actualy opened the motor and checked. I'm tending to be thinking along the same lines as Ed Cregger about air flow through the cowl. ie in flight the airflow is different as compared to on the ground. MVVS actualy make a fitting / static tube that goes over the carp air intake. I think I will try it. Will try the sugestions and let you know on monday how it went on the weekend.

Regards
Warren