All the 2019 Briggs LO-206 Changes You Need to Know

LO 206 class finishes across the line during one of the 2018 heat races for the IKF Sprint Grand Nationals at Fresno Fairgrounds. Photo by Rachel Schuoler.
LO 206 class finishes across the line during one of the 2018 heat races for the IKF Sprint Grand Nationals at Fresno Fairgrounds. Photo by Rachel Schuoler.

Briggs & Stratton released their 2019 rule book back in November. As clubs get started with their 2019 seasons, drivers, teams and mechanics all should be aware of the changes that have been in effect since January 1 of this year. Tri-C Karters has been fielding the largest number of LO 206 classes, and Los Angeles Karting Championship also fielded one class last year.

The biggest rule that has been carried over year after year has been this: “Unless these rules state that you can do it, you cannot do it.” Various teams have pushed the limits of this rule as far as possible, and it seems that each year, Briggs & Stratton have come back with more specifications to build up the most spec class possible. This puts more pressure on the drivers to perform rather than having the most bang for their buck. Not only does it help continue the grassroots tradition of racing, but allows for individuals and families to continue enjoying their passion of racing when on a tight budget and still feel competitive.

Changes with 2019 LO 206 Rule Book – What You Need To Know

This year, it appeared that the LO-206 rule changes focused more on carburetor changes and clarifications. There were other small tweaks with wording in the rule book to help close some corners and further specify what is and isn’t allowed. The first addition was in the introduction which allowed for some flexibility with local clubs.

“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.”

I’ve prepared some side-by-side comparisons of the 2018 rule book vs. the 2019 rule book below. Italics signify a change, bold declares an addition and a strike is a full omission or replacement.

Section 2018 Rule Book (discontinued) 2019 Rule Book (effective)
1. Briggs & Stratton Racing Class Structure The locking cap must be tightened. Locking cap and carburetor cap MUST be tight. Opening verified by pulling on the throttle cable, not pedal, to determine maximum opening.
4h. General Rules Briggs & Stratton 206 classes must have a serialized block. Exception: For early built engines without a block serial number the engine identification sticker must be in place and legible. If the sticker is illegible or missing the engine must be tagged with a suitable sticker or seal approved by the technical inspector. All Briggs & Stratton 206 classes must have a serialized block. Blocks without a factory serialization on the front base next to the oil drain are illegal in competition.
14. Carburetor Overflow Carburetor overflow must be vented to a catch container. Carburetor overflow must be vented to a catch container. The catch-container must be vented to atmosphere.
16. Cooling Shrouds, Covers and Blower Housings No taping or covering of the rewind shroud is permitted. No taping, covering, or restricting of air to the rewind shroud is permitted.
18. Carburetor & Intake Manifold A slight chamfer around the choke bore ID (air horn) may be present. 1.149″ no go Tech Tool A7.

Slide must remain B&S stock unaltered. Slide cutaway to be measured on flat surface. .075 no go Tech Tool A10. ALL intake manifold fasteners to remain factory stock. The use of studs, etc. are illegal.

Idle pilot jet must remain completely stock and be clearly identified with its original etched or stamped ‘32’ as shipped from B&S.

Main jet must also remain completely stock and be clearly identified with its original etching or stamped ‘95’ as shipped from B&S.

A slight chamfer around the choke bore ID (air horn) may be present. 1.149″ no go Tech Tool A7.

Both idle and main jet must remain stock, as shipped from the factory. 9 Slide must remain B&S stock unaltered.

Slide cutaway to be measured on flat surface. .075 no go Tech Tool A10. ALL intake manifold fasteners to remain factory stock. The use of studs, etc. are illegal.

All individual carburetor components must be tight, as shipped from the factory.

Air must only enter the engine from the natural air filter horn of the carburetor. Air entering through any other method is illegal. Air must only enter the engine from the natural air filter horn of the carburetor. Air entering through any other method is illegal. An approved spray test method can be used for tech validation.
18f. Main Jet Main jet – #95, hole size is .0380” 0.036 go, 0.039 no go Main jet – Stock, Unaltered .0365” Go (Use .0365” Class Z Go), .039” No-Go (Use .039 Class Z No-go)
18g. Main nozzle and Emulsion tube Main nozzle – OEM stock unaltered – hole size = .101 min and .104 max inches. No drilling, reaming, slotting or oblonging of hole. Emulsion tube – OEM stock unaltered 4 small holes = .018 min inches to .021 max inches 4 big holes = .026 min inches to .029 max inches. Main nozzle – OEM stock unaltered hole size = .101, .104” Small holes – .018 Go (Use .018” Class Z GO) .021” No-Go (Use .0215” Class Z No-Go) Big Holes – .026” Go (use .026” Class Z Go), .029” No-Go (Use .029” Class Z No-Go)
18k. Venturi Idle Fuel Hole Venturi idle fuel hole = .038 inches max Venturi idle fuel hole =.039” No-Go (Use .039” Class Z Nogo)
26c. Engine Block Deck gasket surface finish is not a tech item. Piston pop up can be .005 inches maximum. Piston pop-up to be checked with flat bar in center of piston parallel to piston pin and then again checked 90 degrees to piston pin. Tech Tool A25. Deck gasket surface finish is not a tech item. Piston pop up can be .0035” maximum. Piston pop-up to be checked with flat bar in center of piston parallel to piston pin and then again checked 90 degrees to piston pin. Tech Tool A25.
32b. Clutch Junior 1, Junior 2, Senior, and Masters Classes can run any rim centrifugal clutch with a maximum of 9 springs and 6 shoes. 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 coolers are not allowed. Sportsman, Junior 1, Junior 2, Senior, and Masters Classes can run any rim centrifugal clutch with a maximum of 9 springs and 6 shoes. 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 or machining to the clutch allowed. Springs, driver, driver conversion, clutch key, and crankshaft fastener kit are non-tech. Springs MUST remain OEM. Clutch coolers are not allowed. The use of aftermarket coatings is illegal.
Tool Kit – Jetting Idle Max: 0.0130 No go

Main Max: 0.039 No go Min: 0.036 Go

Idle Pilot Jet – Stock, Unaltered .0130” No-Go (Use .130” Class Z No-Go)

Main Jet – Stock, Unaltered .0365” Go (Use .0365” Class Z Go), .039” No-Go (Use .039 Class Z No-go)

Tool Kit – Emulsion Tube 4 Small Holes Max: 0.021 Small Holes – Go, .021” plus pin gauge No-Go.

 

About Briggs & Stratton Racing

The 206 engine platform was designed and engineered exclusively for racing. Each engine is hand-built in Milwaukee, Wisconsin using dedicated tooling and dies to provide a level of consistency unmatched in the industry today. The 206 is intended to simplify racing, from hitting the track to the tech process needed to ensure a level playing field at the end of the day. In combination with Briggs & Stratton Racing’s slide restriction system a complete racing ladder can be developed by simply changing a carburetor slide and/or by a slide and ignition change. With the base engine the basis for today’s ‘box stock’ classifications, the 206 engine gives racer’s and tracks the ability to have one engine, from start to finish.

All Briggs & Stratton (B&S) racing engines are manufactured solely for sanctioned racing only. B&S does not recommend the products referenced herein to be used for an application outside of sanctioned racing as serious injury or death could result.

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