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Small Off-Road Engines (SORE)

This page last reviewed February 9, 2010.

Background:



The small off-road engine (SORE) category consists of off-road spark-ignition engines below 25 horsepower, including small utility equipment, lawn mowers and weed trimmers. This category does not include compression-ignition engines, watercraft, or recreational vehicles. The following includes general information regarding small off-road engines and ARB's SORE program:

What's New:

   
  • ARB has released a draft of the supplemental 15-Day Modifications to the Small Off-Road Engines (SORE) regulations amended on November 21, 2008:
  • ARB will be holding a workshop on November 17, 2009 to discuss the California regulations and test procedures for small off-road engines (SORE) with respect to Zero Emission Equipment (ZEE).  Staff would appreciate any constructive comments on the proposed changes.  The workshop notice is available for viewing or downloading from the following page:
  • On November 21, 2008, the Air Resources Board approved proposed amendments to the California regulations and test procedure for small off-road engines (SORE).  Specifically,  modifications were made to the SORE emissions credit program and other minor changes to the regulatory language.  The meeting notice, staff report, and all other regulatory documents can be found at the following link.

  • On April 21, 2008, ARB hosted a public workshop to discuss proposed amendments to the California regulations and test procedure for small off-road engines (SORE) and large spark-ignition engines with an engine displacement less than or equal to one liter (LSI ≤ 1 L).  Specifically, the discussion will focus on standards for LSI ≤ 1 L, modifications to the SORE emissions credit program, and other minor changes to the regulatory language.  This is the second workshop in continuation of the rulemaking process.  The proposed regulations are scheduled to be presented to the Board at the November 20-21, 2008 hearing. (Note:  Board Hearing date change)
  • On November 14, 2007, ARB hosted a public workshop to discuss the proposed changes to California's regulations and test procedures for new SORE and equipment and LSI engines and equipment with engines < 1 liter displacement. Specifically, the discussion focused on standards for LSI engines < 1 liter displacement, modifications to the SORE emissions credit program, and other minor changes in the SORE regulatory language. The workshop notice and presentation can be found below. 
Past Regulatory Activity:

The ARB staff is developing SORE regulations to further reduce emissions from this category. Initially, the staff had sought to develop separate exhaust and evaporative emission control measures for this category. After further review, and at the request of industry, a decision was made to jointly develop a control measure to reduce evaporative, permeation, and exhaust emissions. This control measure was presented to the Board at the September 25, 2003 Board hearing.

A calendar of events has been prepared to provide information regarding the timing of testing and public workshops leading up to the Board hearing. (MSW - 22K) or (PDF - 68K).  The Public Hearing Notice and related materials, including the Staff Report and Proposed Regulations and Test Procedures, for the Small Off-Road Engine and Equipment proposed rulemaking are available at the following ARB web page: www.arb.ca.gov/regact/sore03/sore03.htm.

The Board approved the SORE regulations in 1990 and requested ARB staff to return with a status report twice before the 1999 implementation of the second tier standards. The first tier standards took effect in 1995 and required manufacturers to produce clean engine versions of their handheld and non-handheld equipment. The first status report went to the Board in January 1996. ARB staff met with engine manufacturers and other stakeholders to re-evaluate the 1999 standards. ARB staff proposed changes in the 1999 standards at a board hearing held on March 26, 1998 (please see the mailout #MSC 98-02). These amendments to the regulations were approved by OAL in March 1999.
  • Please view our formal regulatory documents regarding the Small Off-Road Engine Regulations. These documents include, but are not limited to, the staff report, regulations, test procedures, and 15-day notice(s).
What's New Archive:
  • The Third Notice of Public Availability of Modified Text regarding modifications to the Small Off-Road Engine regulations was posted on June 30, 2004. 
  • The Second Notice of Public Availability of Modified Text regarding modifications to the Small Off-Road Engine regulations was posted on May 14, 2004.
  • "Staff Report - Report to the Board on the Potential Electrification Programs for Small Off-Road Programs." (MSWord-327K) or (PDF - 352K)
  •  At the September 25, 2003, Board Hearing, the staff presented and the Board approved modifications to the Small Off-Road Engine regulations originally proposed in the Staff Report (released on August 8, 2003) in response to comments received since the Staff Report was published. A Notice of Public Availability of Modified Text describing the modifications has been posted to the Small Off-Road Engine Regulatory Activity web page at: http://www.arb.ca.gov/regact/sore03/sore03.htm.
  • Durability of Low Emissions Small Off-Road Engines - Final Report (PDF - 2,048KB)
    • Appendices (PDF - 199MB)  (PLEASE NOTE!!!  This is a very large file.) 
  • Off-Road Modeling Change Technical Memo (PDF - 317K)  And see additional SORE inventory related information.
  • Revised Draft Evaporative Regulations, Test Procedures, and Certification Procedures 
  • Draft Exhaust Emissions Regulations and Test Procedures
    • Draft Regulatory Amendments (MSW - 103K)
    • Draft New Test Procedures for 2005 and Later Model Year Engines (MSW - 156K)
  • Draft SORE Evaporative Emissions Methodology (MSW - 211K) or (PDF - 514K)
  • Revised Draft Evaporative Emission Certification Procedures (MSW - 2248K) 
  • Diurnal Testing of Off-Road Equipment Retrofitted with Carbon Canister Evaporative Emission Control Systems (March 2003) (MSW - 62K) or (PDF - 148K) 
  • Durability Testing of Barrier Treated High-Density Polyethylene Small Off-Road Engine Fuel Tanks (March 2003) (MSW - 128K) or (PDF - 98K) 
  • Results of Diurnal Emissions Testing of Walk-Behind Mowers Configured With Fuel Tank Pressure Relief Valves (MSW - 2569K) or (PDF - 188K) 
  • Results of Durability Testing of Barrier Treated High Density Polyethylene Small Off-Road Engine Fuel Tanks (MSW - 120K) or (PDF - 93K)
  • Letter Requesting Individual Manufacturer Meetings with Staff Regarding Information on the Development of Emission Control Technologies for Small Off-Road Spark-Ignition Engines (PDF - 72K)
  • Letter Requesting Comments on the Draft Exhaust Emission Test Plan PDF - 250K)
  • SORE Exhaust and Evaporative Control Measure Integration Announcement (MSW - 44K or PDF - 67K)
Presentations
  • ARB staff presented information on new exhaust and evaporative regulatory requirements at the October 2005 Outdoor Power Equipment Institute Exposition. Information on the Exposition can be found at http://www.opei.org/. Staff's presentations are linked below.
  • ARB staff participated in a seminar at the September 2004 Outdoor Power Equipment Institute Exposition to discuss California's new 2005 and later small off-road engine regulations. The followign is a link to staff's presentation discussing the new evaporative emission certification requirements. PDF - 206 KB)
  • Staff's Presentation from the September 25, 2003, Board Hearing (PowerPoint - 2911K) or PDF - 788K)
Frequently Asked Questions:
  • Leaf Blower Report - The ARB prepared a report to the State Legislature on the health and environmental impacts of leaf blowers on leaf blower operators and the general public.
  • "Staff Report - Report to the Board on the Potential Electrification Programs for Small Off-Road Programs" (MSWord - 327K) or (PDF - 352K)
Where Can I Get More Information:

For more information regarding exhaust emissions, please call Yun Hui Park at (626) 450-6263 or via email at ypark@arb.ca.gov.

For more information regarding evaporative emissions, please contact Jim Watson at (916) 327-1282 or via email at jwatson@arb.ca.gov.

For more information regarding the SORE evaporative emissions inventory and methodology, please contact Walter Wong at (626) 450-6184 or via email at wwong@arb.ca.gov, or David Chou at (626) 450-6136 or via email at cchou@arb.ca.gov.

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