ISO 6855-2:2012

Overview

ISO 6855-2:2012 - Mopeds: Test cycles and specific test conditions defines the laboratory procedures for measuring gaseous exhaust emissions and fuel consumption of mopeds with spark-ignition engines (two‑stroke, four‑stroke or rotary piston). This part of ISO 6855 specifies the dynamometer test cycles, warm-up routines, sampling/dilution arrangements and the specific conditions that ensure repeatable, comparable emissions and fuel‑use results.

Key topics and technical requirements

• Test cycles and warm-up: The standard prescribes urban-style cycles carried out on a chassis dynamometer with brake and flywheel. A warm‑up sequence of four consecutive 112 s cycles is run before the four-element main test (total main test duration 448 s).
• Sampling and dilution: Exhaust gases are diluted with air so that the flow volume of the diluted mixture remains constant. Continuous samples are collected (bag sampling / diluted mixture) to determine average concentrations of CO, unburnt hydrocarbons (THC), NOx and CO2.
• Type 1 (full cycle) tests: Detailed dynamometer operating procedures including gearbox use (manual, semi‑automatic, automatic), acceleration/deceleration behavior, speed and time tolerances (e.g., speed tolerance ±1 km/h, time tolerance ±0.5 s), ambient and test‑room temperature control (approx. 293–303 K), distance measurement accuracy and requirements for plotting speed vs time.
• Type 2 (idle) tests: Measurement of CO and THC emissions at idling for one minute, with gearbox/clutch positions defined for manual and automatic transmissions and analyzer stabilization criteria (steady value within one minute).
• Analysis and reporting: Gas analysis should be completed promptly (within 20 minutes after test end). Presentation formats for emissions and fuel consumption results are specified in Annex A and Annex B.

Practical applications and who uses it

• Vehicle manufacturers and powertrain developers - for certification, engine calibration and design verification.
• Emissions and fuel‑consumption test laboratories - to perform standardized dynamometer testing and produce comparable laboratory data.
• Regulatory agencies and type‑approval authorities - to evaluate compliance with national or regional moped emissions and fuel consumption requirements.
• R&D and environmental analysts - for benchmarking, fleet screening and lifecycle impact assessments.

Related standards and references

• ISO 6855-1:2012 - General test requirements (companion document)
• ISO 6855-3 - Fuel consumption measurement at constant speed (part of the series)
• ISO 4164, ISO 7116, ISO 3833 - referenced for engine power, maximum speed and vehicle classification
• European Commission Directive 97/24/EC is cited as equivalent test‑cycle origin.

Keywords: ISO 6855-2:2012, mopeds emissions test, chassis dynamometer, test cycles, gaseous exhaust emissions, fuel consumption measurement, Type 1 test, Type 2 test, bag sampling, CVS.