1969 Head gasket /cast iron cylinder/ exhaust

[t20sl]

Does a cast iron cylinder and aluminum head use a head gasket on a 1969 125cc?  Looks like it is metal to metal fit.
Also does anyone know if the exhaust mounting flange on a aluminum cylinder for a 1970 Steel tanker is the same as the cast iron cylinder?  Or is the pipe different? Reason I ask is I picked up a aluminum cylinder engine with 4 of the lower fins shortened that is supposedly for a side pipe 1970.  However the pipe off my 1969 does not bolt up.  Fins are not cut away far enough.  Also the exhaust flange has a round hole with 2 studs instead of rectangular. My Sachs manual says that there should only be 3 fins shortened. Maybe this cylinder is for a Puch/DKW??  If so I may need a cylinder that is correct.  Thanks, Ted

[OUCWBOY]

Ted,
This is what I know. No gasket is used. The exhaust flange on the aluminum cylinder is different than the cast cylinder. Pipe from an aluminum will not work on the cast cyclinder.

Donny Smith

[Doug Wilford]

#1 the cast iron cyl. uses no head gasket,  #2 the exhaust flanges on the cast iron exhaust are on the pipe and the aluminum cyl pipe slides on a flange already bolted to the cyl.   The alloy cylinders fins are much bigger than that of the cast iron cylinder there for to fit the same pipe except for the front mounting changes the alloy cyl. fins are cut off.

[firstturn]

t20sl,
1.  All the sachs engines use head gaskets unles they are modified;).
2.  Mounting flange is not the same for steel as to the aluminum cylinder.
3.  Rectangular is for steel and round is aluminum.
4.  On the fin situation I doubt, unless you want a perfectly correct bike, anyone would really notice the fins.  You will probably have to cut another fin to get the pipe to fit properly.  You don't need another cylinder unless you just want to change it.

Ron Carbaugh

[firstturn]

Let me correct #1 all aluminum cyclinder use head gaskets unless modified for other methods to seal the head to cylinder.

Ron Carbaugh

[firstturn]

Doug,
  Saw you post after I had written my response.

Ron Carbaugh

[Lew Mayer]

Doug,
Would you use no gasket on a 152 conversion? My 152 has a solid copper head gasket.

Lewis A Mayer

[OUCWBOY]

Doug,
My 69 with the 152 kit had a head gasket and my current 152 motor also has a head gasket. I have a old motor out of a 69 that is on it's last overbore and it too has a head gasket. The question to you is "Were folks putting gaskets on machines that were more worn and used, or are these just flukes?" You know that we all know that no one knows Sachs motors better than Mr Doug (SACHS) Wilford does and never ever question you on this issue.
Thanks for all you do for us!


Donny Smith

[firstturn]

Donny,
  The aluminum cylinders will fit the 5-speed lower unit if you change the studs the head bolts attach to.  


Ron Carbaugh

[Kip Kern]

I have to agree with Doug, no head gaskets on cast iron cylinders 100/125/152.  Weather "Butch Haircut" head or short radial.  I've got close to 50 Sachs engines (100/125/152)and have never seen a head gasket on a cast iron cylinder.  I know the old shop manual shows one in the parts drawing but I have never seen one in use[?]Good Question

[Paul Danik]

Parts book 001 does not show a head gasket.

Parts books 002 and 003 do show one, however it states that it is needed for the aluminium cylinder only.

[john durrill]

You Folks with the 152's and a head gasket might check and see if the gasket was used to get the deck height right or used to lower the compression. its possible that who ever did the conversion used the gasket , instead of haveing the head machined .
 Just a thought.
John D.

[t20sl]

OK, no head gasket on cast iron cylinder.  I thought from memory that we used to lap the head and cylinder but wasn't sure.  Can anyone who has a steel tank aluminum cylinder look and tell me if there are 3 or 4 fins shortened.  Also are there any oversizes over 55.5mm?  If not I will need a aluminum cylinder with or without fins shortened ( I can shorten a std cylinder).  Thanks

[Kip Kern]

Yes, 70/71 Steel Tankers had fins shortened on the right side of the cylinder as the exhaust pipe goes across that side.  You can get aftermarket Pistons at 56mm and 56.5mm. Tarabusi made them.

[firstturn]

t20sl,
  I have a cylinder that has 3 fins cut for the pipe.  I believe this should answer your question from 2/23/04.

Ron Carbaugh