Overall Rupp History.
Rupp Manufacturing, Inc. was the brainchild of Mickey Rupp, established in 1959. Starting with just eight employees and a 3,000 sqft facility in Mansfield, OH, Rupp initially focused on manufacturing Dart Karts. It wasn’t until 1962 that the company ventured into the realm of mini bikes, marking the beginning of the iconic Rupp Mini Bike legacy.
In their first year of mini bike production in 1960, Rupp produced an impressive 1,000 units. By 1964, Rupp’s ambition expanded, leading to snowmobile prototypes and the establishment of a snowmobile manufacturing division in 1965, with an initial production of 500 snowmobiles.
Rupp’s reach extended to major retailers like Sears, supplying go-karts and mini bikes in 1963 and 1964. The “Sears Cycle” sold through the Sears catalog was in fact the 1963 Rupp Dart Cycle mini bike.
By 1969, Rupp had grown exponentially, employing over 400 individuals in a sprawling 180,000 sqft facility. Their product line diversified to include mini-bikes, ATVs, go-karts, and five distinct models of Sno-Sport snowmobiles.
The year 1970 marked a peak in Rupp’s success, with sales exceeding $30 million. Mickey Rupp’s achievements were nationally recognized when he was honored as one of the “Outstanding Young Men of America.” Snowmobile production alone reached 35,000 units that year.
The company’s expansion continued into 1971, with 850 employees and state-of-the-art facilities, including a research center, administration building, proving grounds, and a styling building, incorporating computerized operations. Mickey Rupp also served as a director of the International Snowmobile Industry Association. However, the boom times were followed by a downturn. By 1972, poor snow conditions led to a market slump, impacting Rupp’s profits and financial stability.
In 1973, facing financial headwinds and potential bankruptcy, Mickey Rupp sold a controlling interest in the company on April 1st to an investment group led by Joseph Hrudka. 1973 also marked the end of Rupp’s engine partnership with Tohatsu, transitioning to Kohler powerplants for snowmobiles in 1974.
The years 1974 and 1975 witnessed a sales decline, attributed to market rumors of business closure, quality control issues, and the change in leadership from the popular founder, Mickey Rupp, to new ownership under Hrudka.
A resurgence appeared on the horizon in 1976 with the introduction of liquid-cooled Xenoah engines in their snowmobiles. SnowSports magazine lauded the 1976 liquid-cooled Nitro model as a top performer. Despite positive reviews and popular models, financial difficulties persisted.
By the spring of 1977, Rupp’s ownership filed for bankruptcy, seeking assistance from Arctic Cat. This partnership resulted in a halved snowmobile production line, down to three models, with Arctic Cat handling the actual production and assembly of the 1977 Rupp lineup. The 1977 Rupp 440 Nitro was celebrated in snowmobile magazines as a muscle sled, boasting an 80HP engine and speeds over 80MPH. However, the challenges were insurmountable, and 1978 became the final model year for Rupp. Rupp Manufacturing, Inc. ceased operations in 1978, marking the end of an era.
Rupp Serial Number Information.
In 1970, Rupp introduced serial numbers starting with “C” on a foil tag under the seat. The serial number location remained on the seat pan in 1971, still on a foil sticker, but the first digit changed to “1”. The “C” serial numbers on 1971 models are considered leftover production from 1970 but applied to early 1971 models. This year-digit format continued until 1976. However, the second digit’s model designation was discontinued after 1971, possibly due to complexity or lack of necessity, coinciding with the standardization of black frames in 1972, suitable for various models.
For 1971 models exclusively, the second digit after “1” indicated the model:
- 1 = Bandit
- 2 = Black Widow or Swinger Trail (both black frames). Black Widows typically fall in the “1 200001” to “1 204000” serial range, with an estimated production of around 4000 units. Observed ranges are between “1 200520” and “1 203661”. Swinger Trail serials lack a space between the “1” and subsequent numbers, unlike Black Widow serials.
- 3 = Enduro
- 4 = Hustler
- 5 = Rascal
- 6 = Roadster2
- 7 = Scrambler
Note that 1971 models with “C” serial numbers (likely late 1970 builds) do not use this second digit model designation. In 1972, model ID designation ceased, with only the first digit indicating the year. From 1973 to 1976, serial numbers were stamped into the seat pan edge, a more durable method than foil stickers.
Top: 1971 Rupp serial number for a Black Widow.
Middle: 1971 Rupp serial number for a Roadster2.
Bottom: 1972 Rupp serial number, model unknown.
Top: 1971 Rupp Swinger Trail (JC Penney) serial number within the Black Widow range, distinguishable by frame differences and no space between the first and second digit.
Middle: 1970 Rupp “C” serial number, model unknown.
Bottom: 1970 Rupp “C” serial number on a January 1971 Black Widow.
Rupp Mini Bike History and Information.
1962 marked the debut of the first Rupp mini bike, the Dart Cycle. This model featured front suspension, rear drum brakes, 5″ two-piece wheels with grease ports, and Goodyear tires. It was equipped with a 2.5 HP 4-cycle Lauson engine and a Fairbanks-Morse clutch, priced at $199. The Dart Cycle continued into 1963 as the Rupp Dart Cycle Deluxe, now with 6″ wheels and an optional 3.5hp motor. Model identification tags were placed on the frame. While Rupp discontinued the Dart line in late 1963, the Rupp Dart Cycle remained available through the Sears catalog as the “Sears Cycle” until 1964.
1962 Rupp Dart Cycle minibike advertisement.
1963 Rupp Dart Cycle Deluxe minibike.
1964 Sears catalog showcasing the Rupp Dart Cycle minibike as the “Sears Cycle”.
1963 saw the introduction of the Rupp Dart Ridge Runner, also known as the trail scooter. It featured a 3 1/2 HP Lauson engine with a belt drive system and dual fuel tanks. A passenger seat was positioned above the fuel tanks. It was available exclusively in high-visibility orange.
From 1964 to 1967, the Rupp Minibike lineup was dominated by the “Continentals,” succeeding the Dart series. Models included the Continental Custom with full suspension and a 3.5hp H35 engine, the Continental Special featuring front suspension but a hardtail and a 2.5hp H25 engine, and the Econo-Cycle with a 2.5hp H25 engine and a side gas tank, also offered in kit form. Lighting was optional for these models. In 1965, the wheels transitioned to Grand Prix mags. The 1967 Rupp mini bike catalog provides visual details. All Continental models utilized Lauson engines and 6″ wheels. In 1964, Rupp introduced headlights and taillights as options, along with chrome chain guards and fenders. The Continental series included various sub-models like the Electra, Custom, Special, and Cub. Late 1965 also saw Tecumseh 3 1/2 HP engines used on Continentals.
1964-1967 Rupp Continental Custom mini bike with Lauson 3.5hp engine.
Continental model variants:
- Continental Electra: 3.5hp Lauson engine, front and rear suspension, front and rear lights, available in red, gold, or blue.
- Continental Custom: 3.5hp Lauson engine, front and rear suspension, red, gold, or blue color options.
- Continental Special: 2.5hp Lauson engine, front suspension, red color.
- Continental Cub: 2.5hp Lauson engine, no suspension, gold color.
- D-300: Go-kart with Tecumseh H25 2.5hp engine, live axle.
- Dart Concession Kart: Tecumseh H35 3.5hp engine.
- Chevy Jr: Tecumseh H35 engine, scaled-down Chevy SS car replica, fiberglass body, blue with white stripes.
- Fun Kart: 2.5hp Lauson engine.
1967 Rupp Continental Special mini bike with Tecumseh H25 motor and optional battery-powered lights.
1968 marked the introduction of visually striking “eye candy” mini bikes from Rupp. The 1968 Rupp mini bike catalog showcases these models: TT-500, XL-500, XL-350, C-500, C-350, C-250, Cub. Color options included metallic blue, metallic red, and metallic gold. All bikes featured 6″ turbine wheels. The model numbers generally reflected engine horsepower (“500” for 5hp, “350” for 3.5hp, etc.). Tecumseh became the exclusive engine supplier. Cable-operated disc brakes were a unique feature for 1968 Rupp models. Models were designated with a “C” followed by a number indicating engine size. The Continental series continued with the C-350, C-250, and the economy C-220 Cub, which had a non-chrome chain guard, scrub brake, smaller seat, and different fuel tank, available as a discounted kit.
A largely original 1968 Rupp TT-500 mini bike with Tecumseh H50 motor.
Higher-end models like the XL-350, XL-500, and TT-500 featured front and rear disc brakes, headlight/taillights, chrome chain guards, automatic clutches with jackshafts, external spring shocks (front and rear), and noncontinuous forks and handlebars. The TT-500, the top-tier model, had a unique chain guard and a two-speed jackshaft. The XL-350 and XL-500 were mechanically identical, differing only in engine size (3.5hp and 5hp respectively) and featuring a single-speed jackshaft. The 1968 frames had a one-piece motor plate. 1968 was the final year for the Continental mini bike series.
1968 Rupp XL350 mini bike with Tecumseh H35 engine and aftermarket Dellorto carb.
Model Specifications for 1968:
- TT-500: Tecumseh H50 engine, 2-speed, front & rear lights, jackshaft.
- XL-500: Tecumseh H50 engine, front & rear lights, jackshaft.
- XL-350: Tecumseh H35 engine, front & rear lights, jackshaft.
- C-350: Tecumseh H35 engine, front and rear suspension, blue.
- C-250: Tecumseh H25 engine, front suspension only, red.
- C-220 Cub: Tecumseh H25 engine, no suspension, gold (kit form available).
- Chevy Jr: Tecumseh H35 engine, Chevy SS car scaled replica, fiberglass body, blue with white stripes.
- D-300: Go-kart with Tecumseh H25 engine, live axle.
- Fun Kart: Tecumseh H25 engine.
Since 1968 marked Rupp’s exclusive use of Tecumseh engines, understanding Tecumseh engines is crucial. Tecumseh acquired Lauson engines in 1956 and gradually phased out the Lauson design, rebranding models as Tecumseh by 1967. Smaller Tecumseh motors like the H25/H30/H35 (2.5hp/3hp/3.5hp) were “small frame” motors, often designated “HS” for small frame horizontal shaft models, although H25/H30/H35 models didn’t always carry the “S” designation. In 1968, Tecumseh introduced the HS40 4hp small frame motor, which became Rupp’s standard engine in the 1970s. The HS50 motor (small frame) followed in 1972 but wasn’t used in traditional Rupp mini bikes like Roadsters. The 1968 and 1969 Rupp models with 5hp Tecumseh motors utilized the wide-body H50 motor with a balloon logo. With the shift to streamlined spoke wheel bikes in 1970, the wider H50 motor was no longer suitable, leading Rupp to adopt the smaller frame Tecumseh HS40 motor as their primary engine for models like the Roadster. Tecumseh HS40 motors had model numbers on the blower housing.
Examples of Tecumseh HS40 motor model numbers used by Rupp:
- Tecumseh H50 65151h – 1969 Roadster (with lighting coil)
- Tecumseh H35 45303g – 1970 Sprint, gray
- Tecumseh H35 45304g – 1970 Scrambler, gray
- Tecumseh HS40 55295c – 1970 Fox, gray, diaphragm carb (non-angled intake)
- Tecumseh HS40 55282b – 1970 Roadster lighted version, gray, diaphragm carb (non-angled intake)
- Tecumseh HS40 55330c – 1971 Black Widow, Dellorto carb, long governor arm removed (first motor revision for BW)
- Tecumseh HS40 55331c – 1970 Roadster lighted version, gray, diaphragm carb (non-angled intake)
- Tecumseh HS40 55355c – 1971 Hustler, with angled intake, also seen on Black Widows with Dellorto carb and governor arm removed (second motor revision for BW)
- Tecumseh HS40 55356c – 1971 Roadster2 lighted version, black, with angled intake
- Tecumseh HS40 55388c – 1972 Roadster lighted version (date code #1337c, #2032b, #2070c)
- Tecumseh HS40 55286b – 1970 Speedway Scarab (date code 0232) white engine with lighting coil
- Tecumseh H50 65151H – 1968/1969 white engine with lighting coil used on 1969 Rupp Roadsters and 1968 Rupp TT/XL500 models.
Rupp, not Tecumseh, handled exhaust and carburetor installations. The same HS40 model number could be used on different Rupp models with varying carburetors and exhaust systems. For instance, the governor disabling on Black Widow models was performed by Rupp, not Tecumseh.
1969 Rupp Goat mini bike featuring the original Tecumseh H50 engine.
The 1969 model lineup saw name changes from 1968. The 1969 Rupp mini bike catalog details models like Roadster, Goat, Scrambler, and lower-tier models Digger, Sprint, Banchi, Chopper. All featured 6″ turbine wheels and Tecumseh engines. Roadster & Scrambler models introduced rectangular headlights (a 1969 innovation) and tail/brake lights with a single-beam power switch mounted directly on the light. Full exhaust pipes and drum brakes became standard. The motor plate was now two-piece, unlike previous single-piece designs. Gas tank undersides differentiate 1969 tanks from 1968 models; 1969 tanks have three round disks with mounting nuts, while 1968 tanks have a triangular plate with welded studs. Five color options were available: metallic blue, metallic green, red, yellow, and orange. The 5hp motors remained the wide-body Tecumseh H50 with a balloon logo.
Model variations for 1969:
- Roadster: Two-speed jackshaft, Tecumseh H50 (5hp) engine, rectangular headlight and rear bake/tail lights.
- Goat (aka Ram): Two-speed jackshaft, Tecumseh H50 (5hp) engine, no lights.
- Scrambler: Tecumseh H35 3.5hp engine with lights (similar to Roadster), single-speed jackshaft.
- Digger: Tecumseh H50 5hp engine, no lights, metallic blue only.
- Sprint: Tecumseh H35 3.5hp engine, no lights, metallic green only.
- Banchi: Tecumseh H25 2.5hp engine, no lights, no rear suspension, yellow only.
- Chopper: Tecumseh H25 2.5hp engine, entry-level, no frills, orange only.
Rumor suggests that General Motors or Bonham Tote Gote threatened legal action over the “Goat” model name (GM trademarked “Goat” for their GTO car), leading Rupp to rename the “Goat” model to “Ram”.
1969 Rupp Roadster mini bike with original Tecumseh H50 motor and aftermarket Dellorto carb, plus Rupp optional chrome exhaust.
1969 Rupp Roadster mini bike restored with “bang bars” and optional chrome exhaust.
1970 was a transformative year for Rupp. The 1970 Rupp mini bike catalog showcases the complete redesign of all models. New motorcycle-style frames, 20-degree angled engine mounts, Torque Converter drives (TC-1), and 10″ spoke rims (Roadster, Enduro, Scrambler only) were introduced. 1970 was the only year Rupp utilized 10″ spoke wheel rims, imported from Italy and fitted with US-made tires, using 3/16″ individual ball bearings. Sanremo was a primary Italian rim supplier. Center kickstands became standard. Rupp employed a 20-degree slanted engine plate with diaphragm carburetors, which function effectively at an angle due to the absence of a float bowl. 10″ models (Roadster, Enduro, Scrambler) featured the TC1 torque converter with a Comet TC88 style 200421a torque converter belt (5/8″ wide, Rupp #15162). Lower-end 6″ turbine wheel models included Sprint and Chopper. Available colors were metallic blue, red, and orange. Engines and gas tanks were silver metallic with balloon Tecumseh logos. The wide Tecumseh H50 motor was replaced by the smaller frame Tecumseh HS40 motor, although the HS40 was introduced in 1968, it gained prominence in Rupp bikes in 1970. All models except Chopper had headlight brackets. Number plates replaced headlights on Enduro, Scrambler, and Sprint models. Angled engines used diaphragm carbs. Headlight-equipped bikes (rectangular) now had handlebar-mounted light switches with lo/hi beam. Seats featured “RUPP” silkscreened in tall, bold letters.
1970 Model Lineup:
- Roadster: Front & rear lights, TC-1, Tecumseh HS40 4hp engine with lighting coil, 10″ spoke rims, exterior front fork springs.
- Enduro: New for 1970, number plate (no lights), TC-1, Tecumseh HS40 4hp engine, 10″ spoke rims.
- Scrambler: Number plate (no lights), Tecumseh H35 3.5hp engine, 10″ spoke wheels, no front brake.
- Sprint: Number plate, Tecumseh H35 3.5hp engine, No TC-1 (standard clutch), 6″ wheels/tires.
- Chopper: Tecumseh H25 2.5hp engine, entry-level, no frills, no suspension, scrub brake.
1970 Rupp Roadster minibike with 10 inch spoke wheels and original HS40 motor with diaphragm carb.
In 1971, further refinements and changes were made to the mini bike lineup. The 1971 Rupp mini bike catalog highlights these updates, including the debut of the famed Black Widow. Telescopic front suspension was introduced. Roadster2 and Enduro models were available in red, metallic green, and metallic blue. Interior front fork springs replaced exterior springs. Purple metallic was exclusive to the 1971 Roadster2. New 12″ spoke wheels appeared on Roadster2, Enduro, and Black Widow, while 10″ slotted mag wheels were featured on Hustler and Scrambler. Catalog specifications mentioned 36 spokes for 12″ wheels, but 24 or 28 spokes were actually used due to supply variations. Wheel spoke count varied across Roadster, Black Widow, and Enduro models without a clear pattern. Frames were slightly modified from 1970, with the engine mounting point shifted back about 1/2 inch, necessitating a different torque converter belt. 1971-1975 models with TC-1 torque converters used Rupp 17617, Gates 6061, Dayco GTS407, or Goodyear 70003 belts (Comet 88 series #200419 belt is incompatible). This change also required a shorter TC1 cover. Around March 1971, Rupp transitioned from diaphragm carbs to standard Tecumseh float bowl carbs on angle-mounted motors, using a custom intake manifold to level the carb. This coincided with a motor color change from silver to black, with some black Tecumseh HS40 motors initially using diaphragm carbs until March 1971. Seats featured “RUPP” silkscreened in both tall bold and small petite letters.
1971 Model Highlights:
- Black Widow: Tecumseh HS40 4hp engine, Dell’Oroto ua19s carb, TC-1, straight pipe exhaust, 12″ spoke rims, “Rupp Motocross” tires, 24 or 28 spoke rims, black color only. Featured a Dellorto carb and disabled governor on a black Tecumseh hs40 engine. Black rear fender standard, chrome rear fender optional. Estimated production of 4000 units. Engine (Tecumseh 55355c or 55330c) similar to Hustler or Enduro but with modifications like removed governor arm and Dellorto carb setup.
- Roadster2: Tecumseh HS40 4hp engine, front and rear lights, TC-1, 12″ wheels with 24 or 28 spoke rims, “Rupp Trials” tires.
- Enduro: Tecumseh HS40 4hp engine, no lights, TC-1, 12″ wheels with 24 or 28 spoke rims, motocross or trials tires (catalog specified motocross, but trials tires were also common).
- Swinger Trail: Sold by JC Penney, essentially a Roadster2 variant with different hand grips, no Rupp engine decal or seat moniker, black frame, blue gas tank and rear fender, “Swinger Trail” branding on tank and seat, no Rupp branding.
- Hustler: Tecumseh HS40 4hp engine, TC-1, slotted 10″ mag rims, motocross tires, front and rear drum brakes.
- Scrambler: Tecumseh H35 3.5hp engine, slotted 10″ mag wheels, trials tires, no front brake, green only.
- Bandit: Tecumseh H25 2.5hp engine, No TC-1, slotted 10″ mag wheels, trials tires, no front brake, blue only.
- Rascal: Tecumseh H25 2.5hp engine, entry-level, no frills, purple only.
The governor system on the Black Widow’s Tecumseh HS40 engine. Rupp disabled the governor by removing the arm and using the governor spring for throttle mech.
IRC manufactured tires for Rupp, branded as “Rupp Trials” or “Rupp Motocross.” After Rupp’s closure around 1975, IRC continued production, removing the “Rupp” name from sidewalls. 1971-1975 frames for 10″ and 12″ wheel bikes were identical, but swing arms differed: 10″ wheel swing arms were 11.5″ from pivot to tip, while 12″ wheel swing arms were 12.5″.
1971 Rupp engines used, as shown in their service letter.
The 1971 Rupp service letter detailed Tecumseh engine numbers used, noting the shared Tecumseh HS40-55355c engine for Enduro, Hustler, and Black Widow, with Rupp modifying the governor assembly on Black Widow engines due to the Dellorto UA19 carb incompatibility with the standard governor.
1971-1973 JC Penney Swinger Trail, manufactured by Rupp.
The Swinger Trail, produced by Rupp and sold by JC Penney from 1971 to 1973, was essentially a Roadster2 variant with “Swinger Trail” branding and different color schemes (primarily blue gas tank), always with a black frame, and unique handlebar grips.
1971 Rupp Roadster2 mini bike in Purple, 12 inch spoke wheels, original HS40 motor with slant intake and float bowl carb.
1971 Rupp Roadster2 mini bike in Green (unique to this year), 12 inch spoke wheels, early 1971 model with no slant intake and diaphragm carb.
1971 Rupp Black Widow with Dellorto ua19s carb and open exhaust. The Rupp Black Widow was a 1971 exclusive, sold as leftover stock in 1972. Black Widow serial numbers should indicate 1971. Considered a racing bike, its Tecumseh hs40 motor was almost “disposable” due to the Dellorto ua19s carb lacking an air filter.
In 1972, the product line was streamlined. Leftover Black Widows were sold as 1972 models. Roadster2, Hustler, and Scrambler models remained largely unchanged from 1971. A [1972 RUPP CATALOG] is needed for detailed specifics. The primary change was the introduction of black frames across the board, replacing the color-matched frames of 1971. Only the gas tank and rear fender retained color, while swing arms and triple trees became black. Mechanical aspects remained similar to 1971. The Enduro model was discontinued mid-year. Hustler & Scrambler were only available in red. Roadster2 gained a new Copper metallic color option. Seats featured “rupp” silkscreened in petite letters, although some 1972 models still used the earlier tall bold lettering.
1972 Rupp Hustler (black frame) with 10 inch mag wheels and original HS40 motor.
From 1973 to 1976, Rupp entered a new phase, discontinuing all Tecumseh-powered models except the redesigned Roadster2 and SS-5. The 1973 Roadster2 featured a painted front fender, no headlight reflectors, and no rear shock reflectors, with a new decal package and fender stripes. Available in brown metallic with gold decals and a brown seat, or Magenta purple with silver decals and a black seat. All used 4hp HS40 Tecumseh engines with a larger blower housing. Both Roadster2 models had front and rear lights. 12″ wheels used 24 spokes only. 1976 was the final year for the Roadster. Seats continued to feature “rupp” in petite letters.
1973 Rupp Roadster minibike in Magenta with painted front fender and original HS40 motor, note the squared blower housing introduced around 1973 for HS40 and HS50 motors.
1974 Rupp Roadster in “poop brown” color.
In 1972, Rupp ventured into small motorcycles with the Rupp RMT-80. Designed as the last project by Mickey Rupp, it featured a Fuji 80cc kick-start engine, Mikuni slide carb, 4-speed manual transmission, headlight with hi-low beam, tail/brake light, horn, hydraulic suspension, 17″ front and 16″ rear wheels/tires. Marketed as street legal with a 50mph top speed, it realistically achieved around 35mph, but the Fuji engine proved reliable.
1972 Rupp RMT-80 mini-cycle aka mini bike.
In 1973/1974, the L-80 and L-100 models replaced the RMT-80. The redesigned RMT-80 became the L-80, with deleted features like dual-beam headlight, brake light, and speedometer, replaced by a simpler single-beam headlight. It featured larger rear shocks, redesigned rear fender, and alloy front forks, painted candy red. The L-100 shared mechanics with the L-80 but had a 100cc Fuji engine with a 5-speed manual transmission, painted candy blue, and potentially street legal with lights.
1973 Rupp L-80 mini-cycle.
1973 Rupp L-100 mini-cycle.
Also in 1973, Rupp launched the SS-5 (“Swifter Shifter”), a small cycle similar in size to the RMT-80/L-80, powered by a black Tecumseh HS50 5hp engine and TC-1 drive. It featured alloy front forks, alloy wheel hubs, and a silver color scheme with red/white/black decals. It had a 16″ rear and 17″ front wheel, and was the only large-frame Tecumseh-powered bike from Rupp. Dellorto MB22A or UA19s carburetors were used, often with Tecumseh HS50 model #67023 engines from late 1972. It was the last bike with design input from Mickey Rupp.
1973 Rupp SS-5 mini-cycle aka mini bike with Tecumseh HS50 and Dellorto carb.
In 1975, the MX-80 debuted as a stripped-down combination of RMT and L-80/L-100 features, essentially a motocross version of the RMT80 with a Fuji 80 motor, 4-speed manual transmission, alloy front forks, alloy hubs, no lights, and green color only. Engineered primarily to utilize leftover parts inventory, 1975 marked Rupp’s final year of mini bike/cycle production.
1975 Rupp MX-80 mini-cycle.
Rupp Gearing.
Proper gearing is essential for Rupp mini bikes. Over-gearing reduces power, while under-gearing limits top speed. A top speed of 30 to 40 mph is optimal for stock Tecumseh HS40 or HS50 engines at 3600 rpm.
Rupp mini bike gearing specifics:
- 10″ wheels 1970 (Roadster, Enduro, Scrambler): 11 tooth jackshaft, 54 tooth rear (4.9 to 1 ratio).
- 10″ wheels 1971-1972 (Hustler, Scrambler): 11 tooth jackshaft, 54 tooth rear (4.9 to 1 ratio).
- 12″ wheels 1972-1975 (Roadster, Enduro, Black Widow): 10 tooth jackshaft, 54 tooth rear (5.4 to 1 ratio).
Further Reading:
