Tech Inspection, Modifications

12.4.6 WOMEN: Female riders on any size or type of eligible machine. a) Historic Novice b) Grand Prix Novice c) Ultima Novice d) Post Vintage Novice Age 40+ e) Post Vintage Novice Age 60+ f) Post Vintage Women Novice

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 flatslide carbs are allowed on Historic and Gran Prix class motorcycles. Examples include Lake, Lectron, Posa and other period-type flat-slides.Active acceleratorpump-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 TM carburetors are allowed only on Ultima class motorcycles.

Mikuni TMX and Keihin PJ and PWK flat-slide carburetors are not permitted.

Modern D-shape-slide or similar equivalent aftermarket OKO, and Chinese made reproduction carburetors are not 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) Sidestands and protruding lugs must be removed or rubber-covered. At the discretion of the Tech Inspector, certain sidestands 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). Hydraulicallyassisted drum brakes are prohibited. OEM Yamaha and Honda motocross and off-road dual-leading-shoe front brake hubs are allowed only in the Grand 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 AND NUMBER PLATES: All machines must display three number plates -- one mounted on the front and one on each side, mounted in a way that they will not be blocked by the rider. 1. Numbers must be six-inches tall. If a rider’s assigned competition number ends with a letter, that letter must be at least three-inches tall, and placed in the lower-right corner of the number plate. For assigned competition numbers that begin with a letter, that letter must be six-inches tall, and placed to the left of the numeric digits. It is strongly recommended—and may be required at some events—that riders also display three-inch numbers on each side of their helmet and eight-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/her score and numbers are not properly displayed, the protest will be disallowed. There will be no exceptions to this rule.