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PENTON / SACHS / DKW motorcycle

Technical Information Page

Identification / Owner Manuals /  Piston Specs / Motor Tips


Year, Size, Model Identification (Penton bikes)

     Every work day I receive calls from someone looking for parts to restore or repair one of the many models of Penton and KTM motorcycles that were sold from 1968 thru 1982. I am pretty good at knowing what some of the parts many people are calling about, especially if I know what year, model, and size of motor the bike is. It saves a lot of time if the caller knows this information before calling. It also helps if the caller has a part number to identify exactly what part that they are looking for.

To identify what year, size, and model Penton or KTM bike you have, write down the serial number off of the frame (stamped on the steering head).

On the Sachs motors there is a metal plate riveted on the top of the ignition case. Write down the numbers engraved on the plate (e.g.. 1251/6B). This information identifies what style of motor it is however, it may not be accurate because many original cases were thrown out and replaced with another used one when they were busted up from a thrown chain.

Sachs motors were made with 5 and 6 speed transmissions. There were also different versions of transmissions and cases made. These are identified as A, B, or D. The parts for all of these versions of motors are not all the same and even though some look the same and will fit, they will not work. The Sachs motors are fine engineered machines designed to allow the internal moving parts to be precisely assembled. This is why everything is shimmed out. The parts lists show illustrations of every part on the bike frame and in the motors as well as all of the different versions of motor parts. This is useful as a guide to help identify exactly what type of motor that you have.






  photo of "A" engine case half               photo of "B" engine case half

A visual identification can be made to determine if it is an "A" or "B" engine by looking at the 2 photos above. The "A" engine has a larger diameter crank than the "B". Thus, the "A" engine case has a larger crank area which is identified with having only a "single" wall around the outside of the crank area as shown in the "A" photo. The "B" engine has a smaller crank area which has a "double" wall around the outside of the crank area as shown is the "B" photo.

The Penton/ KTM frame serial numbers contain a date code that identifies what month and year the bike was built. These number are stamped on or around by the steering head. In most cases (from 1972+) the first three numbers are the date code. The first number is the year, the next two are the month (e.g.. 403 = March of 1974).

NOTE: All 1968 thru 1971 "steel tank" bikes have a "V" serial number stamped on the steering head. The actual year for these bikes is determined by the number sequence and can be complicated to figure out. See the "Penton Owners Group web site for more information about this.


Owners Manuals  (for all Sachs 100 & 125 engines)

Owners manuals are a must for anyone who has a Penton motorcycle. It not only gives you step by step instructions on how to tear down the motor and rebuild it, it also gives all of the specifications for the bike along with recommended maintenance and adjustment of all of the components on the bike. For anyone who has just obtained a Penton for the first time, the owners manual is a must. The manual should be read first before tearing into anything on the bike!

Owners manuals are available. They come in an indexed ring binder. There are two versions - one for the bikes with Sachs motors - the other for bikes with KTM motors. The Sachs version can also be used for working on DKW, Sachs, Dalesman, Rupp's, Monarks, and any other bike brand that are powered with the Sachs 100 and 125 motors.


Parts Lists

Parts lists are available showing every part on the bike and motors and identify everything with a part number. The illustrations help in determining if something is missing, what order the parts go in assembly, and how many there should be. The part numbers help you to obtain the exact part that you need when ordering.

For the 1968 thru 1973 Penton motorcycles they are sold by model size. Parts lists are also available for 1968 and 1972 DKW and Sachs motorcycles. See the "Penton/ Sachs/ DKW Parts List" page for pricing.




When to Rebore a Cylinder

Maximum allowable piston to cylinder clearance

100cc - .005” + piston clearance

125cc - .0055” to .006”


Specifications for Ring End Gaps

           minimum - maximum

100cc - .004     -    .005   (.010)

125cc - .007     -    .008   (.015)


Clearance Specs for Boring Cylinders

100cc - .0015” to .002”

125cc - .0025” to .003”   Wiseco "M" series pistons -  0.0019 (0.048mm)


Sachs Motors Tips

On Sachs motors, use a case protector on the ignition case. This will help prevent the ignition case from getting busted up, if the chain gets thrown or breaks. These are in stock. Order part #0636-120-000 or check Sachs Engine Parts.

Be careful when splitting the cases so that you do not loose any of the shims. Look for any shims stuck to the case half before they fall off.

Do not remove the bolt on the underside of the motor that looks like an oil drain plug. This is the kick starter stop bolt. To drain the oil on a Sachs motor, remove the clutch cover. It can be done with the motor in the frame and exposes the shifting linkages which also allows you to check and adjust these.

To help in adjusting the shifting properly and accurately, use the Sachs adjusting tool. This tool bolts over the shifter shaft to prevent it from wobbling around while adjusting the linkages and selector boss. This tool is available as part no. 0277-100-000 - see Sachs Engine Parts. Follow the instructions in the owners manual and take your time and double check the measurements for shimming the motor. A motor that is not shimmed correctly will either bind up (if over-shimmed) or will not shift correctly (false neutrals).

Do not speed shift a Sachs motor. When shifting, use the clutch and take time to make “positive” shifts. “Banging the gears in” without using the clutch will quickly wear the selector key and result in getting false neutrals.

Bing Carburetors with side choke: Check the starter slide (part #0686-100-000) to make sure that the wax like material is still on the bottom of the slide. This material seals off the opening of the small orifice in the bottom when the choke lever is not being used. If this material is missing, it is the same as having the choke lever open all the time. EXAMPLE: the bike will start right up and run great when engine is still cold - as soon at engine warms up, it will start sputtering, blubbering, and billowing smoke out of the exhaust pipe.