Interpreting the 2018 Briggs 206 Rule Set

The Colorado Briggs 206
Understanding the 2018 Briggs 206 Rule Set

A Look at the 2018 Rule Set Modifications, Implications

January 18, Boulder, CO – On Thursday, January 18, 2018, Briggs & Stratton’s released their 2018 rule set for the 206 engine package. Known nationwide for their efforts to continue to strive to provide a product and rule set that provides a cost-effective racing engine for karters of all experience levels across the country, the 2018 ruleset looks to be a continuation of this effort.

Below, The Karter has outlined the major rules updates for the coming racing season, and what these updates mean for 206-powered kart racers within the region. All updates mentioned here, and contained in the full-length rule set are available online at:, and also in the Briggs section of The Karter’s “Technical Resources” page. This rule set is effective as of January 15, 2018.

Note: The updates cited below are shown in their complete form, except where shortened for brevity. All implications are the sole speculation of The Colorado Karter, and should not be substituted for nor taken as verbiage representative of the ultimate intent of Briggs & Stratton.

Major Updates

Updated Cover Sheet Verbiage

  • As Written: “This rule package has been prepared by Briggs & Stratton Racing and is intended to establish the sole basis for technical control of the 206 engine in competition. For all supplemental rules contact your sanctioning body.”
  • Implication For Racers: This further clarification by Briggs appears to give some leeway to local racing series and national sanctioning bodies. Essentially, this verbiage establishes the 2018 Briggs 206 Rule Set as the foundational document for all 206 competitions nationwide, but acknowledges that further rules updates or clarifications may be issued by sanctioning bodies or series throughout the 2018 racing season, presumably upon approval by Briggs.

General Rules (Section E)

  • As Written: “A tech official may use additional means of measuring components to compare against a known stock part.”
  • Implication For Racers: This rule should not provide any major update for racers that consistently adhere to all 206 rules already. However, for those that have attempted to ‘stretch’ the existing rules in previous seasons, this rule serves notice that tech officials are being given slightly more lee-way for 2018 in regards to how they may conduct technical inspections of suspicious components. According to Briggs, this addition to the rule gives slightly more flexibility to a tech official, which enhances their ability to prove a racer compliant with existing rules.

Engine Air Filter

  • As Written: “A racer MUST start each race with the air filter properly attached but will NOT be penalized if the air filter falls off during the race. If air filter falls off during a race, it is STILL subject to tech.”
  • Implication For Racers: The performance advantage served by losing an air filter during a competition event is dubious at best. Still, this update simply clarifies that just because a racer lost it during the event, this does not make it immune to technical inspection. Furthermore, it provides assurance to the racer regarding how the loss of an air filter will be handled by race officials regarding grounds for disqualification. According to Briggs, this clarification was issued to standardize how the loss of an air filter is handled by sanctioning bodies across the country. Previously, some organizations would issue a disqualification for the loss of a filter, while others would not.

Engine Fuel (Recommendation)

  • As Written: “Specific gravity and hydrometer testing are acceptable tests when used in accordance to sanctioning body guidelines.”
  • Implication For Racers: To most racers, the use of a specific gravity or hydrometer testing system in technical inspections should not come as a surprise. By issuing this clarification, Briggs is giving some guidance to technical officials or sanctioning bodies regarding how they may conduct fuel inspections and tests. For most racers, this rule update will not affect how their series already conducts these tests.

Carburetor & Intake Manifold

  • As Written: “….NO alterations allowed unless stated below…”; “ALL intake manifold fasteners to remain factory stock. The use of studs, etc. are illegal.”
  • Implication For Racers: The update regarding that no alterations should be made to the carburetor system stems from a previous technical clarification in 2017, which provided tolerances for chamfering (whether intentional or unintentional) of the air horn surface. This update seems to further clarify the previous amendment, returning this tolerance to ‘as stock,’ which leaves no room for interpretation from the racer. In addition, the comment about stock fasteners stems from racers taking it upon themselves in 2017 to ‘update’ or replace factory fasteners with aftermarket mounting studs, which Briggs is adamant will not be allowed. If you have done this modification, consider consulting with Briggs our your series technical official.

Cylinder Head

  • As Written: “Factory machining marks left on the head gasket surface IS a tech item.”
  • Implication For Racers: Albeit subtle, this rule seems quite significant. For many motor builders, the popularity of the 206 has been both a boon, and a curse. As many racers adopt the package, the frequency of rebuilds has plummeted. This has resulted in some motor builders offering ‘built’ 206 packages. While TCK will not and has no interest in speculating regarding these services, the fact remains that these services pose a potential threat to the ‘spec’ intention of the 206. By enforcing factory machining marks, Briggs appears to be taking a further step to keep engine builders from even considering modification of the cylinder head area.

Push Rods (modification part c, addition part d)

  • As Written: “Push rod diameter .183 minimum inches to .190 maximum inches.” ;“Push rod diameter to be checked 3 points along the length and must pass two planes on each 360 degrees of rotation.”
  • Implication for Racers: “According to Briggs, this update to the inspection process follows a realization that the dimensions of the factory-supplied push rods alters slightly from the inclusion and manufacture of the press-fit process of the ball-ends on each push rod. By reducing the pre-press diameter by 0.002” and by implementing the 3-point inspection process, Briggs has worked to ensure that future push rods will more consistently meet the technical specs. It is expected that this update will not affect existing racers, as it accommodates both existing and future push rods in process and tolerance of inspection.

Ignition System (modification part c, addition part d, f)

  • As Written: “Temperature thermocouple permitted as long as sealing washer and/or air guard are not modified.”; Spark plug connector: Only the OEM B&S part #555714 is permitted. ; Static check for timing: – Install a degree wheel using a positive stop method. – With the left edge of the first magnet aligned with the start of the lead leg of the ignition (refer to photo), the engine must not exceed 26 degrees with air gap set at .016”. Timing checked in the direction the engine operates.”
  • Implication for Racers: The first two rule amendments are much needed, and low-impact for the racer. Essentially, these rule updates allow the use of a MyChron (or other data logger) cylinder head temperature probe to be utilized. In previous years, the use of these probes was a gray area for some series and classes. Provided you do not modify the spark plug or the air guard/cooler as delivered by Briggs, the use of these probes is now allowed. The timing update is considerably more significant to tech inspectors, as it provides a simplified method to check appropriate and compliant timing settings on engines. In previous cases, a timing light was often used to inspect this, which of course required more time and skill from tech inspectors.

Clutch (modification part b, c)

  • As Written: “Clutch must be used as shipped from the ORIGINAL manufacturer. Mixing of parts between clutch lines or manufactures or removing parts (ie. Grease guard, etc.) is ILLEGAL. No alteration to clutch allowed except springs, driver, driver conversion, clutch key, and crankshaft fastener kit, which are non-tech.; Clutch hubs must be single-piece steel, other alloys not allowed”
  • Implication for Racers: The clutch used in a specific series or class has always been a point of contention with the 206, as well as most any karting engine package. By issuing this updated verbiage, Briggs essentially clarifies that modifying clutches by mixing manufacturer parts or model types is specifically prohibited. This will save racers testing and development costs, and remove some ambiguity surrounding the issue of clutch options. All previous ‘standard’ options for modification are listed, and likely will not affect or restrict the current habits of most racers. The update to part c comes as an official update to an amendment to a previous issue from 2017, where some racers were found to be using machined or exotic clutch drums. This rule clarifies that machined or modified clutch hubs is also prohibited.

From inspection of the 2018 rule set, The Karter has concluded that the modifications made to the rules continue to demonstrate Brigg’s directed efforts to perpetuate and enhance their commitment to retaining the Briggs Local Option 206 engine as an affordable, consistent, and well-regulated racing engine. We hope that our members take the time to read and internalize all regulations themselves, and urge competitors to reach out to their local sanctioning body or representatives with further technical questions.


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