Barrels

Originally, the SACHS 200 engine had 10,2 HP and for Messerschmitts it was later reduced to 9,7HP. The reason for this change was that at 10.2 Hp it was in a higher insurance category in Germanyand thus raised the cost of insurance for everyone with a car above 10HP. You can differentiate the weaker barrels as they have a K (for Karo) moulded at the left side of the inlet. However, if the engine was used for other applications other than Messerschmitts there was no reason to reduce the power, so late barrels can be found without the K.

To investigate the different types, I took out my stock of barrels in the garden and spent some hours measuring them. The barrel for early Messerschmitts has no K at the inlet and can be recognized by the V-shaped lower edge in the inlet, and also both corners in the top of the inlet have the same shape. The inlet inside the barrel, it is 38mm wide and the slots for the transfer ports in the bottom of the barrel is 26,5mm wide.

The barrel for later Messerschmitts has a K moulded at the left side of the inlet, and the shape of the inlet is a bit different. It is 40mm wide and the bottom is V-shaped and also has a small groove in the bottom. There is an irregular shape in the top of the upper right corner. The width of the slots for the transfer ports is in most cases only 25mm, but I also have some K-barrels where the slot is 34mm! Otherwise I can?t see any difference from other K-barrels.

Finally we have the ?go fast?-barrels. They have no K at the inlet and can be recognized either by a moulded screw head at the left side of the base or a spotweld outside the left transfer port. The inlet is 43mm wide and is not V-shaped on the bottom edge. It is almost rectangular except for the irregular shape in the upper right corner. Another difference from all other barrels is the position of the exhaust port. The normal distance between the top and the port is 42mm but those barrels have only 40mm. If you put a finger in the transfer ports (from the base) you can also find that they are slightly bigger than in other barrels. I?m almost sure that these barrels both come from the Swedish Fram-King-Fulda and also the graveyard tractors. The width of the slots for the transfer ports is 34mm and this explains why I often have been confused why the fit of new pistons is so bad! I often have to cut of 5-6mm from the piston to make it fit the transfer ports. It is a good idea to first put the barrel into one of the crankcase halves, and then adjust the alignment of the transfer port. Then do the same with the other half. Finally put the crankshaft and piston in one crankcase half and with the barrel on you can see how much you have to adjust the slots in the piston. As I am keen on originality I wouldn?t call this tuning, it is only to optimise!

Anders Johnsson, Sweden

Supplementary note from David Garner

I have most of the Sachs archive documents relating to the Sachs 200 engine. These are titled ?SMD Mitteilung?. (SMD = Sachs Motor Dienst). That is Sachs Motor Service in English. I will translate them all in the coming months and publish on the site. There was an exchange service to allow existing German owners to change to the lower power piston and barrel. New registration documents were issued certifying the lower output that granted the less than 10HP insurance rate.