Sachs Cylinder Heads
What's the Difference
by Alan Buehner
In the last Tech Tips article (#57) I showed the difference between the different Sachs cyliders. In this article my intention is to show the difference between the different cylinder heads used on the Sachs cylinders.
The first thing to know is there are cast iron cylinders and aluminum cylinders and there are different heads that go with these.
CAST IRON CYLINDER HEADS
The cast iron cylinders came stock with aluminum heads as shown in photo “A”. They have short “butch” style short fins that were straight up and down These were used on the 1968 thru 1971 Sachs engines.
The cylinder head shown is photo “B” is the head off of a Puch cylinder. These were discoved by the racers to fit the Sachs cylinders and gave the engines a little bit more horsepower. These heads have short radial sunburst fins.
Both of these heads came in 2 sizes, one for the 100cc and another for the 125cc cylinders. The heads are dished out to accommodate the piston domes and allow for the proper “squish” area of the fuel air mixture. The 100cc heads have a smaller dome area measuring 50mm o.d. The 125cc heads have a dome area measuring 55mm o.d. These heads do not use any head gaskets. They simply just bolt onto the cast iron cylinder with 4 hex head bolts and washers.
ALUMINUM CYLINDER HEADS
The aluminum cylinders heads came in 2 styles and are available as 100cc or 125cc. It is important to know the differences between these for the bike application they will be used on. The heads are dished out to accommodate the piston domes and allow for the proper “squish” area of the fuel air mixture. The 100cc heads have a dome area measuring 50mm o.d. The 125cc heads have a larger dome area measuring 55mm o.d.
Photo “C” shows an alloy cylinder heads with the top 4 fins “cut off” on an angle (shown on the left side in the photo). These are used on Sachs engines using an up and over pipe. These are what are required on the Penton 1972 thru 75 CMF bikes where the exhaust pipe goes up and over the cylinder head. This allow a closer fit of the pipe to the head to allow the pipe to clear the frame.
Photo “D” shows an alloy cylinder head with “full” radial fins. These are used on Sachs engines that use a side mount exhaust pipe. These are what are required on the Penton “steel tank” bikes that have the exhaust pipe mounted on the right side of the frame.
The aluminum cylinders require the use of a head gasket when installing the head. They are fastened together with 4 special long reach Allen Head nuts and washers.
The 100cc head gasket part number is 0650-113-000.
The 125cc head gasket part number is 0650-114-000.