SECTION 12 - POST-VINTAGE MOTOCROSS
AHRMA’s Post-Vintage Motocross structure is intended to include and categorize the motocross bikes that inspired the “long-travel” revolution that transformed motocross into a sport that very different from the earlier, short-travel era. This program groups similar motorcycles into classes that are similar to the changes that were taking place at the racetracks throughout the intended era of each class. Please submit any requests for new rules or machine eligibility to the Post-Vintage Motocross Rules & Eligibility Committee (see Section 17).
NOTE: All modifications must be consistent with the intended time frame of the class.

12.1 HISTORIC - CLASSES AND ELIGIBILITY
The Historic classes are intended to represent the “first generation” of long-travel bikes that were commercially available in the 1975-77 period. The time frame is provided only as a guideline, as some 1977 models are of the second generation long-travel bikes that would clearly outclass the earlier models if allowed to run together. For this reason we do not classify motorcycles strictly by the year they were produced, but by some similar characteristics that were possessed by the majority of these first-generation long-travel motorcycles, such as suspension travel.

12.1.1 Historic classes technical specifications. The following specifications apply to all motorcycles, regardless of the year of manufacture, that fall within the scope of the Historic classes.
a) Regardless of original specification, no Historic class motorcycle may have more than 9 inches of suspension travel at the front and rear wheels. Period aftermarket suspension modifications, including shock reservoirs, are allowed in the Historic classes, provided they still meet the 9-inch travel limit.
b) No water-cooled motorcycles.
c) 35mm leading-axle Husqvarna and Betor forks are allowed, provided travel is limited to a maximum of 9 inches. Early 9-inch-travel Simons forks are allowed. Fox Factory Forks are prohibited.
d) 38mm is the maximum diameter of fork tube allowed for the Historic classes.
e) Overhead cam four-strokes (TT Yamahas, XL Hondas, etc.) are limited to a maximum of 500cc of displacement, plus allowable overbore.

12.1.2 Historic 125: Certain 88-125cc machines built up to and including the 1977 model year that made up the first generation long-travel, small bore motorcycles. Eligible machines include:

1975-77 Bultaco Pursang 125
1975-77 Can-Am TNT, Qualifier and MX 125, up to MX3 (MX4 and later see Gran Prix classes)
1975-78 CZ 125
1975-78 Honda CR, MR, MT 125
1975-77 Husqvarna CR, WR 125
1975-77 Kawasaki KX, KE, KD 125
1975-77 Maico 125 GP
1975-77 Montesa Cappra 125 VA & Enduro 125. VB, 1977 & 1978 models only; no later-model components, including swingarm.
1975-77 Penton/KTM 125 with Sachs or KTM engine. (1978 Penton/KTM is not a like-design model. See GP classes.)
1975-77 Suzuki RM, TM, 125
1975-77 Yamaha MX, YZ, DT, 125

1975-77 Bultaco Pursang, Frontera, Alpina 250, to include the 1977 MK10 Pursang
1975-77 Can-Am MX, TNT and Qualifier 175-250, up to MX3 (MX4 and later models see the Gran Prix classes)
1975-78 CZ 250 Falta Replica
1978 Harley-Davidson MX250
1975-77 Honda CR, MT, MR, XL 175-250
1975-76 Husqvarna CR, WR 250 and 1977 WR 250. 1977 Husqvarna CR/OR models are allowed, with fork travel limited to 9 inches. Otherwise, see GP 250.
1975-77 Kawasaki KX, KLX, KD, 175-250. 1978 Kawasaki KX250A4 (exceptional performance of this model may move it to the GP class).
1975-77 Maico MC, AW 250. 1977 model AW 250 must comply with the Historic class suspension limits.
1975-77 Montesa King Scorpion & Cappra VR 250 V-75, VA & Enduro 250H. VB, 1977 & 1978 models only; no later-model components, including swingarm. All later model Montesas, see GP classes.
1975-77 Ossa Phantom & Desert Phantom 250, up to GPIII model. 7. Ossas equipped with the “Bolger” rear suspension are allowed in the Historic class, provided that the suspension travel limits are met.
1975-77 Penton-KTM 175-250. 1977 models must meet the Historic Class suspension limits. (1978 Penton/KTM is not a like-design model. See GP classes.)
1975-76 Puch 250 MX (twin-carb Harry Everts replica)
1975-77 Suzuki RM, TM, PE 175 & 250
1975-77 Yamaha MX, YZ, DT, IT 175-250

12.1.4 Historic 500: Certain 325-460cc two-stroke and up to 636cc four-stroke machines, built up to and including the 1977 model year, that make up the first generation long-travel motorcycles. Eligible motorcycles include:

1975-77 Bultaco Frontera, Alpina, Pursang 360-370
1975-78 CCM MX up to 636cc. No CCM four-valve heads are allowed. Wheel travel must comply with Historic class requirements.
1975-78 CZ 400 Falta Replica
1975-77 Honda XL350, side- or center-port engine
1975-76 Husqvarna CR, WR 360. 1977 WR 360 is allowed. 1977 Husqvarna CR and OR 390 are allowed (frame numbers between ML16000 and ML21000), with fork travel limited to 9 inches. Otherwise, see GP 500. 1975-77 Husqvarna 360 and 390 Automatics are allowed.
1975-77 Kawasaki KX 400-450
1974-77 Maico MC, AW 400-440. 1977 AW 400-440 must comply with the Historic class suspension limits.
1975-77 Montesa Cappra 360 VA. VB, 1977 and 1978 models only, with original 360cc 4-speed engine; no later-model components, including swingarm. All later model Montesas, see GP classes.
1975-77 Penton-KTM 400. 1977 models must meet the Historic class suspension limits. (1978 Penton/KTM is not a like-design model. See GP classes.)
1975-77 Suzuki RM, TM, PE 370
1975-77 Yamaha YZ, MX, DT, IT 360 and 400
1975-80 Yamaha TT500, up to 500cc displacement, with allowable overbore.

12.1.5 Historic Four-Stroke: Certain four-stroke motorcycles built up to and including the 1978 model year with up to 636cc (with restrictions). All overhead cam four-stroke engines are limited to a 500cc maximum displacement, plus allowable overbore. Eligible motorcycles include:

1975-78 CCM MX up to 636cc. No four-valve CCM heads are allowed. Wheel travel must comply with Historic class requirements.
1975-78 Honda XL350 with side- or center-port head
1975-80 Yamaha TT500; must meet 9-inch suspension travel limit
Any period special that meets the Historic class technical requirements and was built within the intended time frame of the class. (e.g., Triumph engine in a Husqvarna frame, etc.)

12.1.6 Motorcycles in all of the Historic classes may use an aftermarket frame. Many were available during the intended time frame of the class, including, C&J, Champion, Dick Mann, Cheney, Cycle Factory, Hallman-Aberg and many others. Regardless of the manufacturer, all motorcycles must meet the Historic class technical specifications for wheel travel and suspension components.

12.2 Gran Prix - Classes and Eligibility
The Gran Prix classes are intended to represent the motorcycles that made up the “second generation” long-travel motorcycles generally available in the 1977-81 period (or like design). During this period innovation came rapidly and motorcycles changed dramatically in a fairly short time. For this reason, the Gran Prix Classes follow a formula rather than a specific year cutoff.

12.2.1 Technical specifications. The following class specifications apply to all motorcycles that fall within the time frame intended for the Gran Prix classes: No linkage-type rear suspensions, no water cooling and no disc brakes. There are no travel limitations. Motorcycles in the Gran Prix classes are allowed to use an aftermarket frame and forks. Many were available during the intended time frame of the classes. Upside-down forks are not allowed (see the Ultima classes).
If there is a question regarding eligible frames or other components, you should submit a request for eligibility form.

12.2.2 Gran Prix 125: Certain post-1977 motorcycles 88-125cc. The year of manufacture is unimportant, so long as the motorcycle meets the class formula.

1981 model: Honda, Suzuki, Yamaha, KTM and Kawasaki models are prohibited. See the Ultima class.
1978-83 Husqvarna 125s are allowed.
1978-80 Yamaha, Honda, Suzuki, Can-Am and KTM 125cc motocrossers are allowed.

12.2.3 Gran Prix 250: Certain 126-250cc post-1977 motorcycles. The year of manufacture is unimportant, so long as the motorcycle meets the class formula.

1981 model: Honda, Suzuki are prohibited. See Ultima class.
1978-83 model Husqvarnas are allowed.
1987-89 CZ 250 is allowed.
1980 and later model Kawasakis are prohibited. See Ultima class.
1978-81 Maico 250s are allowed.
1978-81 Can-Am Qualifier and MX up to MX6 are allowed.
1978-80 Suzuki, Yamaha, Honda motocross and enduro models are allowed.
1981 Yamaha YZ250 is allowed.

12.2.4 Gran Prix 500: Certain post-1977 motorcycles, 325-500cc two-stroke and 580cc four-strokes. The year of manufacture is unimportant, so long as the motorcycle meets the class formula, with a few exceptions (see below).

1981 model: Honda, Suzuki are prohibited. See Ultima class.
1983-84 Husqvarna TE, TC, TX four-Stroke 510s are prohibited. See Ultima class.
1982 and later Can-Am Sonic with Rotax engines are prohibited. See Ultima class.
1978-84 Husqvarna CR, XC, OR, WR 390-500 two-strokes are allowed. 1978-1984 Husqvarna 390, 420 and 500 Automatics are allowed.
1980 and later model Kawasakis are prohibited. See Ultima class.
1978-81 Can-Am Qualifier and MX 370-400 up to MX-6 are allowed.
1987-92 CZ 400 is allowed.
1978-81 Maico 400-440-490 are allowed.
1978-80 Mugen 360-kitted Honda CR250 is allowed.
1982 Suzuki DR500Z is allowed.

12.2.5 Gran Prix FOUR-STROKE: Certain 185cc-580cc four-stroke motorcycles that came just after the Historic Four-Stroke period. Eligible motorcycles and modifications include:

All Honda XR185, 200, 250, 500 models produced with dual-shock rear suspension
Four-valve CCMs
Yamaha TT 250 & 500, with more than 9” of wheel travel, front & rear.
Suzuki DR models to include the 1982 DR500Z
Kawasaki KLX models
Period specials that meet the class requirements.
Can-Am Sonic & Husqvarna 510 TE, TC & TX prohibited. See Ultima Four-Stroke class.

12.3 ULTIMA - CLASSES AND ELIGIBILITY
The Ultima classes are for machines that bring us to the brink of the modern motocross motorcycle. The distinguishing formula for the Ultima classes are that these motorcycles must have been produced within the following formula: Ultima class motorcycles CAN have been produced with water cooling and have a linkage type rear suspension, but they CANNOT have been produced with disc brakes or any power-valve type mechanism built directly into the engine.
12.3.1 Technical specifications. Upside-down forks, such as Simons and early White Power, are allowed only on Ultima class motorcycles. Aftermarket single-shock frames (such as C&J) are allowed on only Ultima class motorcycles.

12.3.2 Ultima 125: For certain motorcycles 88-125cc that were produced within the guidelines of the Ultima class specifications. Eligible machines, and exceptions, include but are not limited to:

1982 and later Kawasaki 125s are prohibited.
1985 model 125 Husqvarnas are prohibited.
Honda CR125s up to 1983 are allowed.
Suzuki RM125s up to 1984 are allowed.
Yamaha 125s, up to the 1982-84 YZ125 with YPVS system, are allowed. (Note: these are the only eligible motorcycles allowed to use a power-valve mechanism.)

12.3.3 Ultima 250: For certain 126-250cc motorcycles produced within the guidelines of the Ultima Class specifications. Eligible machines, and exceptions, include but are not limited to:

1982 and later Kawasaki 250s are prohibited.
1982-84 Maicos and/or M-Star, air-cooled drum brake only.
1983 Hondas and Suzukis are allowed.
Honda XR200, all years.
Yamaha 250s, up to the 1982-84 YZ250 with the YPVS system, are allowed. (Note: these are the only eligible motorcycles allowed to use a power-valve mechanism.)

12.3.4 Ultima 500: For certain 325-580cc motorcycles produced within the guidelines of the Ultima Class specifications. Eligible machines include but are not limited to:

1982-83 Can-Am Sonic with Rotax four-stroke engine
1983-84 Husqvarna 510 four-strokes
1981-83 Honda CR450-480, 1981-82 XR500. 1983 XR500 is prohibited.
1980-81 Kawasaki KX420
1982-84 Maico and/or M-Star, air-cooled drum brake only.
1983-84 Yamaha TT600 (not XT600). Note: This is the only model allowed in the class that is over the displacement limit of 580cc. Typical overbore guidelines still apply to this model.

12.3.5 Ultima FOUR-STROKE: Certain 200cc-580cc four-stroke motorcycles that were produced with either a single-shock rear suspension or a newer engine technology. Eligible motorcycles and modifications include:

1983-85 Husqvarna TC, TE, TX 510 four-stroke
1982-84 Can-Am Sonic with Rotax engine
1981-82 Honda XR, 200, 250, 500 with Pro-Link rear suspension (1983 XR 500 is prohibited). 1983 model XR350 with RFVC is allowed. XL350 models are prohibited.
1983-84 Yamaha TT600 (Note: XT600 is prohibited). This is the only model allowed in the class that is over the displacement limit of 580cc. Typical overbore guidelines still apply to this model.

12.4 ADDITIONAL CLASSES
12.4.1 Open Age: Any AHRMA-eligible rider on any eligible machine.
12.4.2 +40:- For any rider over 40 years of age on any eligible machine.
12.4.3 +50: For any rider over 50 years of age on any eligible machine.
12.4.4 +60: For any rider over 60 years of age on any eligible machine.
12.4.5 Women: For women riders on any eligible machine.
NOTE: A rider may not advance to the next age-related class until after that birthday.

12.5 TECH INSPECTION AND MODIFICATIONS
a) SUSPENSION: The field check for rear wheel travel, where applicable, is as follows:
1) Both shocks are removed from the bike, then one bare (without spring) damper unit is reinstalled.
2) The machine is supported in such a fashion that the rear suspension is at maximum extension, and a measurement is taken from the center of the rear axle to a point marked directly above the axle on the rear fender or subframe.
3) With both wheels on the ground, the rear suspension is fully compressed by the examiner with the rider aboard to compress any rubber bumpers; a measurement is again taken from the center of the rear axle to the same marked point above.
4) The measurement obtained in step 3 subtracted from the measurement in step 2 is the wheel travel. An alternative method of determining wheel travel may be used by tech inspectors using a pre-programmed computer. The program converts three dimensions - distance from swingarm pivot to rear axle, to lower shock mount and top shock mount - to show the amount of travel of the shock shaft plus 50 percent of the rubber bumper. Due to the use of non-standard or different types rubber bumpers, this check may be overridden by the tech inspector’s discretion. Manual measurement of shock movement is the overriding factor in determining whether a shock is legal.
b) Alloy swingarms in the Historic classes must be period aftermarket or OEM units. Use of later-model OEM alloy swingarms on Historic-class motorcycles is prohibited. Modification of Ultima-class single-shock alloy swingarms for use on dual-shock Gran Prix motorcycles is prohibited. Use of period aftermarket or accurate replica alloy swingarms in all Post-Vintage classes is allowed.
c) Engines: Modifications are many, though they must be consistent with the spirit of the period and class. Cylinders may be overbored a maximum of .080” on singles, .060” on twins, .040” on triples and .020” on fours.
d) CARBURETORS: Period-type carburetors are strongly encouraged. Period flat-slide carbs are allowed on Historic and Gran Prix class motorcycles. Examples include Lake, Lectron, Poso and other period-type flat slides. Active accelerator pump equipped carburetors are allowed only on Ultima class motorcycles; all others must be disconnected or removed, even if OEM equipped. Dell’Orto accelerator pump carburetors are allowed in the Historic and Gran Prix classes only if the accelerator pump mechanism is disconnected or removed. Period flat slide Mikuni carburetors are allowed only on Ultima class motorcycles. Keihin flat slide carburetors are not permitted. No modern D-shape slide or similar equivalent carburetors are allowed in AHRMA Post-Vintage off-road competition.
e) Hydraulically assisted clutches are prohibited.
f) For Gran Prix and Ultima machines, any OEM or aftermarket fork may be used up to and including the Ultima era.
g) All motorcycles must be equipped with a functional handlebar-mounted kill switch.
h) Footpegs must be folding type and should fold back at a 45-degree angle.
i) Side stands and protruding lugs must be removed or rubber-covered. At the discretion of the Tech Inspector, certain side stands which are completely tucked away may be left in place but must be safety wired or strapped in the folded position.
j) Disc brakes are prohibited (except OEM on Rokon and Yankee). Hydraulically assisted drum brakes are prohibited. OEM Yamaha and Honda motocross and off-road dual-leading-shoe front brake hubs are allowed only in the Gran Prix and Ultima classes.
k) Paddle-type tires are prohibited.
l) All two-stroke machines must be fitted with efficient silencers.
m) Minicycles are prohibited. All machines must have a minimum OEM wheel size of 17 inches.
n) All modifications must be consistent with the spirit of the class and period. The burden of authenticating is on the rider. Press clippings and photos with identifiable dates may be helpful.
o) Appearance and workmanship of a reasonable standard shall be enforced.
p) NUMBERS: All machines must display three number plates - one mounted on the front and one on each side mounted in a way that it will not be blocked by the rider.
1) Numbers must be at least 6 inches tall; when used, letters must be upper case and at least 3 inches tall, and appear in the lower-right corner of the number plate. It is strongly recommended - and may be required at some events - that riders also display 3-inch numbers on each side of their helmet and 8-inch numbers on the back of their jersey.
2) All number plates will use a “school bus” yellow background with black numbers and letters. Competitors on machines eligible for AHRMA’s Vintage MX program may retain their black-on-white number plates and Vintage number, but must inform Registration. To help solve past scoring problems, no other colors may be used.
3) It is the rider’s responsibility to ensure number legibility. If a rider appeals his score and numbers are not properly displayed, the protest will be disallowed. There will be no exceptions to this rule.
4) Expert-class champions from the previous year will be awarded a #1 plate (with a letter suffix), which they may use in any class during the season. If they choose not to use their assigned AHRMA competition number, it will be held for them until the following season. A rider who wins more than one class championship should use only one of the #1/letter combinations to aide in scoring and identification. Number-letter combinations for each Expert class champion are:

5) All competitors must display their AHRMA-assigned number unless granted prior permission to run a different number at that event only.
q) In addition to the rules in Section 11, riders must comply with all applicable rules in Sections 3 (events and race procedure), 4 (entry procedure) and 6 (offenses, penalties, protests and appeals), rule 9.7.11 (fuel) and rule 9.7.17 (AHRMA decals; two required and may be placed on any readily visible part of the motorcycle).

12.6 GENERAL MOTOCROSS RULES
The following rules in the Vintage Motocross section also apply to AHRMA Post-Vintage MX:
11.3 Motocross Rider Grading System (Note: Rule 11.3h, dual ability level, does not apply in Post-Vintage classes.)
11.4 Scoring at AHRMA Events
11.5 Series Points Awards
11.6 Race Procedures

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