{"data":{"id":"us/40-cfr-86.508-78","jurisdiction":"us","citation":"40 CFR 86.508-78","heading":"-78 Dynamometer.","body":"(a) The dynamometer shall have a single roll with a diameter of at least 0.400 metre.\n(b) The dynamometer shall be equipped with a roll revolution counter for measuring actual distance traveled.\n(c) Flywheels or other means shall be used to stimulate the inertia specified in § 86.529.\n(d) A variable speed cooling blower shall direct air to the vehicle. The blower outlet shall be at least 0.40 m 2 (4.31 ft 2) and shall be squarely positioned between 0.3 m (0.98 ft) and 0.45 m (1.48 ft) in front of the vehicle's front wheel. The velocity of the air at the blower outlet shall be within the following limits (as a function of roll speed):\nActual roll speed Allowable cooling air speed\n0 km/h to 5 km/h 0 km/h to 10 km/h.\n5 km/h to 10 km/h 0 km/h to roll speed + 5 km/h.\n10 km/h to 50 km/h Roll speed ±5 km/h.\n50 km/h to 70 km/h Roll speed ±10 pct.\nAbove 70 km/h At least 63 km/h.\n(e) The dynamometer shall comply with the tolerances in § 86.529.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER C—AIR PROGRAMS","PART 86—CONTROL OF EMISSIONS FROM NEW AND IN-USE HIGHWAY VEHICLES AND ENGINES","Subpart F—Emission Regulations for 1978 and Later New Motorcycles; Test Procedures"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"108e32dd92d21375e38e9635fa6c045d735f606fc332569a7d22fa427213eb79","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-86.505-2004","next":"us/40-cfr-86.509-90"},"notice":"GroundRules: Original legal text. Not legal advice."}