Production Year Guide

By Bill Smith

The following is a guide to help identify the model and year of the Penton motorcycle. The Penton motorcycle development was an on-going venture. It was not uncommon for changes to be made in the middle of a model year. Therefore, the following material may or may not totally be accurate to a given year. If you find information in the list that you feel needs addressing, please contact Penton Owners Group.
Last update 11/07/05

The Steel Tank Bike Era


  • (Starting Serial No. V001)
  • 100cc Sachs powered 5 speed Berkshire introduced with gas tank, air box and rear shock body, all finished in red
  • 125cc Sachs powered 5 speed Six-Day introduced with gas tank, air box and rear shock body, all finished in green
  • All frames are painted silver
  • Gas tank is 2.5 gallon and made of steel
  • Small white Penton decals with model name and size on upper front sides of gas tank with lettering being straight or angled
  • All Sachs engines come with cast iron cylinder and vertical finned (butch) heads or short finned sunburst Sachs high compression head or Puch short finned sunburst head
  • Engines came with Bosch point type ignition and 24 mm Bing carburetor
  • Air box is cast aluminum 10 1/4" tall enclosed frame style - later same year models came with shortened 7 1/2" tall version for better air flow
  • Frames came without welded on fork stops if equipped with Ceriani steering dampener that contained an adjustable dampener knob on the triple clamp and self-contained fork stops - later same year frames came with frame welded fork stops and no steering dampener unit
  • Early models came with twist on/off gas caps - later same year models came with flip top gas caps
  • Two piece front engine mount
  • Chrome expansion chamber on very first models
  • 16" long seat
  • 35mm Ceriani forks with long rubber accordion boots
  • Fully covered Ceriani rear shocks finished in chrome with matching model paint
  • 4 bolt rear sprocket carrier hub assembly
  • Steel chain guard (20” along top)
  • Curved style center stands
  • Magura controls with oval shaped throttle - later models are round
  • Narrow polished aluminum front fender and tubular steel fender brace with brace having an overall width of 3"
  • Skid plate welded to frame
  • Non-high breather frame
  • Expansion chamber with stinger tip
  • Cast aluminum barrel style front and rear hubs
  • Chrome spokes
  • Aluminum or chrome rims
  • Head light is large color coordinated 5 3/4" diameter x 7 3/4" long bullet shape


Same as 1968 except for the following:

  • Ceriani rear shocks finished in black with chrome bell
  • Shortened polished aluminum or steel chain guard (11" along the top)
  • High breather frame
  • 8" round air box with gray plastic cover (husky style) or same cover with black rubber elbox attached to high breather frame
  • 6 bolt rear sprocket carrier
  • Silver painted spokes
  • Center stand now straight with mounting area angled and flattened
  • First Jackpiner introduced limited to one "experimental" unit only, model finished in bronze with silver side panels, 175cc Puch engine, six speed gearbox, Bosch point type ignition and 27 mm Bing carburetor, Ceriani front fork and rear shocks and Magura controls (Note: This model was never put into production.)

Late 1969

  • Second Jackpiner introduced in limited numbers having a blue gas tank with white side panels and a white "Penton Jackpiner" decal on upper front sides of gas tank (Note: Blue tanks have been found with Six Day decals on sides.)
  • Jackpiner is powered by 152cc cast iron cylinder conversion kit on existing Sachs engine
  • Jackpiner models were basically converted over Berkshire models that were not selling
  • 100cc and 125cc Sachs engine introduced with cast aluminum alloy cylinder, and sunburst head
  • Engines came with Bosch point type ignition and 27.5mm Bing carburetor
  • Expansion chamber with removable muffler for Sunburst head and cylinder
  • Inner corner gussets added to swing arm
  • Head light is large 5 3/4" diameter bowl shape


Same as 1969 except for the following:

  • Most came with newer 20" long seat
  • Same 35mm Ceriani front forks but without accordion boots
  • Center stand mounting area is now straight
  • Front fender brace overall width is widened to 5"
  • 7" long horizontal tubular frame extension on bottom left side of frame to attach optional down swept MX expansion chamber
  • 4 threaded holes on top of gas tank for optional tool bag
  • Bars added under side number plate to support rear frame loop
  • One piece front engine mount
  • Removable skid plate
  • Frame tabs enlarged for swing arm pivot bolt


Same as 1970 except for the following:

  • Triangular gussets between top of rear engine mount and frame
  • Head light is large 5 3/4" bowl shape or 4" diameter small bullet shape

The Chrome Moly Frame (CMF) Era


  • First year for total redesign of 100cc Berkshire and 125cc Six Day with serial numbers starting at 10600000 ( the first digit represents the year and the next two digits represent the month, i.e. 1 = 1971 and 06 = June)
  • New 175cc Jackpiner introduced with all new KTM engine
  • Jackpiner has blue gas tank and air box along with yellow number plates
  • 175cc KTM engine is black with Motoplat ignition, 6 speed gear box, cast aluminum alloy cylinder and head with 30mm Amal carburetor
  • Early Jackpiner serial numbers start with 7-206xxxxx (7 being a production code and the next 3 digits indicate year and month, i.e. 2 = 1972 and 06 = June)
  • Jackpiner expansion chamber has a two ported outlet muffler fastened on with 3 nuts and bolts
  • 100cc Berkshire still red
  • 125cc Six-Day still green
  • 100cc and 125cc are still Sachs powered
  • Early 1972 model year 100cc and 125cc Sachs engines (known as 5A) came with Bosch point type ignition and 5 speed gear box - later model year engines (known as 6B) came with Motoplat ignition and 6 speed gear box - both came with cast aluminum alloy cylinder, sunburst head, and 27.5mm Bing carburetor
  • Front forks are 32mm Ceriani - early 100cc and 125cc model forks had a center to center leg distance of 6 1/4" - later models and all 175cc models had a distance of 6 3/4"
  • 100cc and 125cc expansion chambers have cone shaped muffler with internal baffle held in place with 3 springs
  • Chrome Moly tubing now used in frame construction
  • All frames are painted silver
  • Non-high breather frame
  • New fiberglass 3.1gallon gas tank (nicknamed toaster) and air box
  • Small white Penton decals with model name and size on upper front sides of gas tank and 2 white stripes underneath
  • Magura controls
  • All models have yellow number plates
  • Cast aluminum barrel style front and rear hubs
  • Chrome steel rims
  • Ceriani rear shocks
  • Side stand is mounted underneath the swing arm on the left side
  • Expansion chamber has removable chromed heat shield with 6 large holes
  • Air box comes equipped with triangular shaped painted aluminum cover that also forms an oval number plate
  • Front and rear fenders are aluminum
  • Gas tank is held in place by a buckled leather strap
  • Head light is small 4" bullet shape

1972 Penton Wassell Era

  • Observed trials (Mud-Lark) model first appears
  • 125cc Sachs engine (known as 6B) came with Bosch point type ignition or Motoplat ignition, 6 speed gear box, aluminum alloy cylinder and sunburst head, and 22mm Amal carburetor
  • Engines also available - alloy Sachs 5 speed, cast iron Sachs 5 speed, and 152cc Sachs 5 and 6 speed
  • Polished aluminum narrow profile 1.5 gallon gas tank
  • Polished aluminum alloy front and rear conical hubs
  • Chrome steel rims
  • Frame is Reynolds 531 tubing finished with hammered silver paint
  • Ground clearance is 12 1/2"
  • Polished aluminum fenders, air cleaner covers and chain guard
  • Still air box
  • M.P. 600 teledraulic front fonk with timken taperd roller bearing steering head
  • Girling rear shocks
  • High level "Big Bore" chrome exhaust pipe (sometimes called torque pipe) with silencer in matte black and polished aluminum heat shield
  • Constant drip chain oiler filled at main frame tube
  • Spring loaded chain tensioner
  • Cable actuated rear brake
  • Wassell controls


Same as 1972 except for the following:

  • 100cc and 125cc models are still Sachs powered
  • Side stand is mounted on side of left swing arm
  • Girling rear shocks
  • Chain guide block area is redesigned with extra brackets
  • All models have white PVC (plastic) fenders
  • All models now have black finished cast magnesium alloy barrel hubs
  • 175cc engine is still black but now comes with a 30mm Bing carburetor
  • New 1.8 gallon MX style fiberglass gas tank is introduced
  • Head light is either large bowl shape (5 3/4" diameter) or small bullet shape (4" diameter)

1973 1/2 (June '73) Hare Scrambler

  • 250cc Hare Scrambler introduced with all new KTM engine - note that a few brochures and magazines called this model a "Mint"
  • Hare Scrambler has a gold tank and air box along with dark green number plates
  • 250cc KTM engine is black with Motoplat ignition, 6 speed gear box, cast aluminum alloy cylinder and head with 34mm Bing carburetor
  • New swing arm, right side rear brake linkage and conical rear hub
  • New high breather frame for Hare Scrambler and all other models
  • Expansion chamber has a two ported outlet muffler (vertically oblong) fastened on with 2 nuts and bolts
  • All models still have 32mm Ceriani forks except the 250cc which has 35mm forks
  • Expansion chamber has removable chrome heat shield with slotted cutouts
  • October 1973 was the last of the gold Hare Scramblers - these models at this point had fiberglass exhaust heat shields/number plates - some also came with unpainted cylinders even though head and gear box is still finished in black


Same as 1973 except for the following:

  • November 1973 - 250cc is now red and is still called "Hare Scrambler"
  • 250cc MX models had green number plates
  • 250cc Enduro models had yellow number plates
  • December 1973 - 18" long seat now 3 1/2" thick (previously was 2 1/4" thick)
  • All models have 35mm Ceriani forks
  • Gas tank decal is a long wide black and white stripe with the word "Penton" in white
  • New fiberglass 2.9 gallon low profile design enduro tank (nicknamed "watermelon") replaces the previous "toaster" enduro tank
  • All models have color coordinated fiberglass exhaust heat shields/number plates
  • New rear brake arms with holes
  • All KTM engines are now finished in silver and come with a round profile clutch case cover
  • 250cc and 400cc now have megaphone style pipe with large removable chrome tip
  • 175cc came with original and megaphone style pipes
  • KTM engines now have 2 piece kick starters
  • New rear fender mounts are contoured stampings tin mounts located on corners of rear frame loop
  • KTM powered models (175cc, 250cc and 400cc) had high shouldered Akront rims and conical rear hubs
  • Head light is large bowl shape
  • 100cc and 125cc are still Sachs powered
  • 100cc and 125cc now have early style 175cc muffler
  • 100cc and 125cc still have barrel hubs and chrome rims
  • Last year for 100cc Sachs powered Berkshire model

1974 Cafe MX

Same as 1972 Mud-Lark except for the following:

  • Model has headlamp and tail lamp
  • HiPoint knobby tires
  • Was advertised as a "Dual Purpose" machine
  • Tank decals were red and white and read "Cafe Motocross"
  • 152cc Sachs engine though other sizes may be found

1974 1/2 (April '74)

Same as 1974 except for the following:

  • 400cc Mint introduced with all new KTM engine
  • Mint has white gas tank and air box along with yellow number plates
  • 400cc (actually 352cc) KTM engine is silver with Motoplat ignition, 6 speed gear box, cast aluminum alloy cylinder and head with 38mm Bing carburetor
  • New frame and swing arm with 6 shock mounting positions for the 175cc, 250cc and 400cc KTM models - all 100cc and 125cc Sachs models still maintained early suspension designs
  • 125cc Sachs "D" series engine introduced
  • Ceriani gas shocks
  • GP seat, 21" long by 3 1/2" thick
  • Right side air box mount eliminated
  • Tank held down by two spring cables with aluminum retainer ring around tank filler neck
  • New center U bracket rear fender mount
  • Forged aluminum brake stays
  • Late 1974 - 200mm (non-ribbed) forks, quick release rear brake arm and front brake arm with holes


Same as 1974 except for the following:

  • January 1975 - reinforced lower steering stem race and long rear brake stay with chain guide
  • May 1975 - Ceriani 200mm ribbed forks
  • Last year for 125cc Sachs powered Six-Day model still with old style suspension
  • First and only year for 125cc Sachs powered Six-Day model with special MX frame having 3 shock hole positions in frame and 1 shock hole position in swing arm

1975 Hiro

Same as 1975 except for the following:

  • Engine was Italian built Hiro 125cc
  • Engine was mounted in 1975 Six Day model
  • Chain drive on left side
  • Production was limited to 20 or less


  • Model line diverged into two distinctly different models - the MC5 and the Cross Country
  • December 1975 brought the debut of the new 125cc KTM engine with 32mm Bing carburetor
  • 125cc engine has black cylinder and head fins with "125 KTM" cast in side of cylinder with silver gear box - all other engine sizes are totally finished in silver


  • Starting serial number is 55000000 (MC5's only)
  • First year for MC5 (MC means motocross and 5 means 5 speed through many are found as 6 speed)
  • MC5 model came in 125cc, 175cc, 250cc and 400cc sizes
  • New non-breather frame and swing arm with magnesium air box
  • Marzocchi shocks mounted at 45 degree position with no other adjustment postions
  • Motocross seat with integrated rear fender
  • Leading axle Marzocchi or Ceriani forks
  • Sun rims
  • New 2.1 gallon gas tank
  • Finish is orange with yellow number plates
  • MC5 gas tank decal was a long wide black and white stripe with the word "Penton" in white
  • West Coast KTM bikes were mostly red and a few of the very first MC5 400's were white; European models were blue

Cross Country

  • This model is often called the GS6 - the GS6 actually came out the following year
  • Engine sizes were 125cc, 175cc, 250cc and 400cc
  • Frame and shock setup same as 1975 KTM powered line
  • Rear brake and separate chain guide same as 1974
  • New 2.9 gallon gas tank with "toaster" styling somewhat similar to that of 1972
  • Finish is orange with yellow number plates
  • Tank has black "Penton" name surrounded on two sides by black and white L-shaped stripe
  • Front forks are Ceriani ribbed or Marzocchi
  • Rear shocks are Marzocchi
  • Rear brake stay is short style though some literature shows long style
  • Head light is Preston Petty or similar molded plastic head light number plate
  • Trip V.D.O. speedometer
  • Sun rims


  • First year for GS6 model (GS means Gelande Sport and Gelande means terrains ) and 6 means 6 speed)


  • MC5 same as 1976 except new black with white trimmed C-shaped decal around the word "Penton" which was in black
  • Frames had a slight but noticable modification on some brackets as compared to the 1976 where the rear of the seat bolts on
  • Some frames had the option to mount the foot pegs in two different height settings
  • Exhaust pipe had an extra strengthening gusset on top where the silencer is welded on to the pipe

GS6 Cross Country

  • Starting serial number is 70100000 (GS6's only)
  • Has MC5 frame styling with the exception of new high breather tunnel type backbone
  • New orange enduro tank, side panels and headlight/number plate
  • Tank decal like 1976 Cross Country model
  • Has leading axle Marzocchi forks
  • Rear shocks are Marzocchi
  • Lectron and Bing carburetor
  • Sun rims

1977 Penton Woodsman

Same as 1972 Mud-Lark except for the following:

  • Woodman model first appears
  • Gas tank is polished aluminum and orange finish
  • Penton white PVC (plastic) front fender and Preston Petty white IT (integral taillight) rear fender
  • Ceriani 200mm front forks
  • Koni rear shocks
  • Upswept expansion chamber (husky type) with muffler and heat shield
  • Full enduro lighting complete with large bowl shape headlight
  • Seat is 1974 Penton model (thick 18" long)
  • Frame turns up behind seat to accommodate Preston Petty Enduro fender

1977 Penton/ K-R (Kenny Roberts)

  • New short tracker model introduced mid-February
  • 250cc KTM 5 speed engine, 40mm Lectron carburetor, Motoplat ignition
  • Cranke designed expansion chamber
  • Frame is K-R designed and tested by Kenny Roberts
  • Handlebars and fiberglass body work are K-R designed
  • Wheels and disc brakes are A.D.E products
  • Magura controls
  • Ceriani forks
  • S & W shocks
  • Carlisle tires

Frame Identification

All 1972 thru 1977 Penton motorcycles have an 8 digit serial number stamped on the steering head of the frame. The actual serial number is the last 5 digits. The 3 digits preceding the 5 digits is the date code. The first digit indicates the year, the second two digits indicate the month. For example, a serial number of 30161040 would be January of 1973. Some bikes have an extra one or two digit production code number such as 7, 51 or 54 ahead of the year, month, and serial number. For example 54 41078651 would still indicate an October of 1974 date by disregarding the 54 production code number. The 1976-77 MC5 and 1977 GS6 models did not follow the above dating code. They all start with 550xxxxx on the MC5's or 701xxxxx on the GS6's. However, in both cases the last 5 digits are the serial number.

Engine Identification

To determine the year of a KTM engine, you need to find the engine number. For this, look for the numbers stamped on the engine case, just below the bottom cooling fin of the cylinder, on the ignition side of the engine. The engine number is coded with the first digit determining the year and the next two digits determining what size the engine is, and the last 5 digits would be the serial number. If the first digit is a “3” then the year is 1973, a “4” would be 1974, and so forth. If the second and third digit is one of the following, this would be the engine size: 51=125cc, 52=175cc, 54=250cc, 55=400cc. Thus a engine number beginning with 654 would indicate that it is a 1976 250cc.

All KTM engines also have date stamps as part of their case castings. These are two small casting clocks, one located under the countershaft and the other underneath the left side of the engine. These clocks have an arrow in the center pointing to one of the numbers from 1 thru 12. The numbers indicate the months of the year with the arrow pointing to the month the casting was produced. Note: This is not necessarily the month the engine was assembled. Under the arrow is a two digit number indicating the year, i.e. 75 = 1975. The castings also have cast part numbers in the recess pocket area on top of the cases. These again follow the codes for engine size by observing the first two digits (i.e. 52 indicates 175cc).