Just sharing some information.
For those who love 4 stroke can take a look into RCV engines.
Some of facts that I know off and used.
1. RCV brand is from UK and they have started a new technology of 4 stroke glow engines that has require low maintenance.
2. RCV engines can turn large propellers due to the 2:1 gear ratio.
For further information you can check out at
www.rcvengines.comChanging the bearing and installing back the engines is very-very simple compare to Saito or OS. All you need just use two pieces of tooth pick or cocktail sticks.
Regards.