So, Sunday afternoon, wanted to take some time to ensure the timing of my rotary disks compared to the piston position. First thing I noticed was that no pistons are in TDC when the line on the rotor lines up with the crankcases, not sure if this is normal or not. Then you can see in the video, that as the pistons on the opposing cylinders come to TDC then rotary valves are just at the cusp of starting to shut.
So as the piston rises it is leaving low pressure in the crankcase which is drawing in fuel from the carbs through the rotary disk, as the piston reaches TDC the disk port can then start to shut as the piston starts downwards, as the disk closes the inlet port the piston compresses the mixture in the crankcase, finally releasing it through the transfer ports into the top of the cylinder, then the piston continues upwards closing the transfer port and then the exhaust port (quite a lot higher) until finally compressing the fuel/air mixture in the top of the cylinder until the spark plug fires (before TDC) to push the piston around again. in the video I am mixing up cylinder 2 and 3 - obviously the diagonally opposite cylinders are pairs i.e. 1 & 4 and 2 & 3.
So as the piston rises it is leaving low pressure in the crankcase which is drawing in fuel from the carbs through the rotary disk, as the piston reaches TDC the disk port can then start to shut as the piston starts downwards, as the disk closes the inlet port the piston compresses the mixture in the crankcase, finally releasing it through the transfer ports into the top of the cylinder, then the piston continues upwards closing the transfer port and then the exhaust port (quite a lot higher) until finally compressing the fuel/air mixture in the top of the cylinder until the spark plug fires (before TDC) to push the piston around again. in the video I am mixing up cylinder 2 and 3 - obviously the diagonally opposite cylinders are pairs i.e. 1 & 4 and 2 & 3.
