Evaluating a Sachs Engine

By Paul Danik

Photos by Alan Buehner

Originally printed in issue #71 of Still....Keeping Track

There was a posting on the POG message board asking what should be looked for when considering purchasing a Sachs engine. This was my response.

Whenever I look at any Sachs engine, either in a frame or not, I always pull the ignition cover, even if it looks good from the outside.

Occasionally the cover is damaged from the chain as well as the engine case. I also to inspect the end of the crank. The nut holding the flywheel on is a left hand thread and I have seen a perfectly good looking engine with the end of the crank snapped off from trying to loosen the nut in the incorrect direction. There can also be damage to the end of the crank or the threads from work done in the past, can be a real mess.

Those engines can usually be bench tested as far as shifting, turn the sprocket by hand as you shift the tranny with your other hand. I can't say that you can tell if it is perfect, but you can get a decent indication as to what is going on inside. You can do the shift testing even if the top end is locked up by removing the clutch as mentioned below, then test the shifting.

While you have the ignition cover off you may be able to grab the flywheel and feel if the piston wants to move. I have used chain vise grips tightened carefully around the flywheel to get what seemed like a tight engine to break loose, some oil poured down the plug hole never hurts.

It never hurts to pull the clutch cover off and see just how the oil looks and see if there is any indication of water being trapped inside. While you have the clutch cover off it only takes a minute to pull the clutch off and see just how everything looks and turns. The clutch is held on with a snap ring which is easily removed with circlip pliers. When you lift the clutch off be sure to check that the grooved washer from the three piece bearing under the clutch isn't sticking to the underside of clutch and drops off into wherever those things disappear to.

Doug Wilford always recommended that one does not try to open the bottom oil drain plug as the threads just might come out of the case with the bolt, plus occasionally a person might remove the wrong bolt in the bottom of the engine allowing the kickstarter spring to move and requiring a disassembly of the engine.

In my opinion, a Sachs engine with a good ignition cover, undamaged cases, good end on the crank shaft on the ignition side, clean oil and no sign of water internally, that shifts nicely thru the gears, and with the two ends of the main shaft by the sprocket both intact, is getting to be a rare bird. They are probably worth more that they fetch when comparing what the repairs to a damaged engine would cost.

Hope this helps…

Photo showing engine with severe breaks in case from a thrown chain. The black arrows point to the breaks. Note also that end of main shaft is broken. The white arrow points to where the split end was broken off.
Photo showing end of crank broken off. The black arrow shows where the threaded end was broken off. The white arrow shows where a chunk of the case is missing, from a thrown chain.
Photo showing the crank area of an engine. This engine was sitting for many years with no oil in the gear box. The clutch is all rusty and chances are the inside gears are also. The arrow points to the circlip that secures the clutch assembly.