AMA Competition Bulletin MX18101: Clarification of the Limited Class Air Box Rule
Tuesday, April 24, 2018 | 3:10 PM
To: AMA Amateur Motocross Competitors
From: AMA Racing
Date: April 20, 2018
Subject: AMA Competition Bulletin MX18101, Clarification of the Limited Class Air Box Rule
The purpose of this Competition Bulletin is to clarify the limited class rules with regard to air boxes. The air box may not be changed or modified. The air box cover is considered part of the air box.
For reference, the following is from the 2018 AMA Racing rulebook, Section 1.2 Motocross Equipment.
B: 1. To be eligible for a LIMITED CLASS, the following ARE NOT PERMITTED to be changed or modified:
| Air Box | Front Forks |
| Air Box Vent Tube | Front Fork Caps |
| Air Filter Screen | Intake Spacer |
| Air Intake Boot | Internal Engine Components (blue printing is not allowed) |
| Axle | Lower Triple Clamp |
| Brake Rotor Size (thickness/diameter) | Oil Injection System (only oil may be in system) |
| Brake Master Cylinder | Rear Shock |
| Carberetor (including any parts with exception to jets) | Reed Valve Assembly (any part) |
| Clutch (any part including clutch cover) | Rim Size |
| Crankshaft Stroke Length | Silencer (tip may be modified to accept spark arrestor) |
| Cylinder Bore Size | Subframe |
| EFI Throttle Body | Swingarm |
| Electronics | Transmission (any internal part) |
| Exahust Control Valve (ECV) | Yamaha PW50 Start/Run/Off Switch |
| Exhaust Pipe (any part) | Water Pump Assembly (any part except the cover) |
| Frame | Wheel Hubs |
Questions may be directed to [email protected]