Updated 206 Engine Supplemental Guide

Briggs & Stratton 206 Racers Guide

This guide is a supplement to the instruction sheet included with your Briggs & Stratton 206 Racing engine.  Investing a few minutes before hitting the track and throughout the day or weekend is what leads to success on the track and determines the life of your engine. 

This guide is interactive allowing you to click on highlighted links throughout for more information.

There are two critical choices that each racer must make that can completely change your racing experience with our racing engines:

• Oil – Although karting oils can be used in our racing engines we now recommend racers stay away from these products because of the knowledge, understanding, and limitations inherit to them.  You have a sealed bottom-end so it becomes the determining factor in engine life.  Karting oils typically do not have additive packages to prevent wear or stability agents to maintain film strength for extended periods of time.  These products use a base material originally designed for closed loop systems which makes them magnets to absorbing water when exposed to air.  The functionality of these products relies on you changing them out frequently or they will fail.  This is why we do NOT recommend using ‘karting’ oils. 
• While there are hundreds of oils on the market we can only offer recommendations based on what we have tested and used in developing this program.  The Amsoil 4-stroke Dominator series or Redline 20 or 30 weight racing oils are built using premium materials and additives package that will protect your engine and allow longer intervals between changes.

 

• Air Filter -The air filter you choose will directly impact engine life.  The biggest mistake a racer can make beyond their choice of oil is trying to save money with a cheap, paper filter.  We believe in this statement so much that our Green air filter, part number 555729, is passed through to retail within dollars of cheap paper filters to help make your decision easy.  This is a premium filter when oiled and cleaned on a regular basis will prevent engine wear by keeping contaminants from entering your engine.

  A couple of critical points:
• Green air filters comes from the factory DRY.  It is essential to oil BEFORE using or after washing.
• Know how the manufacturer recommends cleaning and re-oiling their filter.
• Green has a picture tutorial HERE
•   Green air filter oil is readily available online or through most auto parts stores.

• Things to understand:
•   It is a must to have basic knowledge of how to set the float height.  A detailed video can be viewed HERE.
•   In shipping and even in transit to and from the track (if the fuel has been drained) could cause the float setting to change.  
•   The float setting is a fine tuning instrument that can be adjusted from track data or by understanding how the engine is performing on the track.

 

• If the engine ‘bogs’ out of a corner or a rough track is creating a miss chances are too much fuel is in the bowl and the track condition is highlighting this.  
• If this is from a bump -Raise the float height  
• If it is in a turn (in and out of the gas) your adjustments are (and we recommend one at a time remembering your initial setting): 
• Raise the float height in small increments of .015” (reducing the fuel in the bowl).
• Drop the needle (which will limit the fuel into the throttle body of the carburetor from idle to 1/4 throttle.)
• Open the spark plug gap (Taking advantage of the power of the PVL digital ignition to create a large spark to help overcome a momentary rich condition.
•   If you have a lean condition which the engine is ‘flat’ during long straightaways or you are seeing elevated head or exhaust temperatures.
• First ask yourself WHERE this is happening?  If it is in a turn, etc. could it be your chassis is too tight and it isn’t an engine condition?  Is your chain becoming too tight causing your engine to labor?
• If you isolate it to the carburetor here are some adjustments that can be made:
• Lower your float height, again in .015” increments, to allow more fuel into the bowl.
• Turn your air bleed adjuster (1/4 turn at a time) located on the side of the carburetor counter clockwise.  This will reduce the initial feed of air lowering your air/fuel ratio from idle to ¼ throttle.
• To set your initial starting point turn this counter clock-wise until the screw stops and then turn this screw counter clockwise 1.5 revolutions.

 

• Valve Lash - Valve lash is a simple adjustment that each and every racer will need to know how to set in order to maintain optimum engine performance.  If the valve lash is too tight it will keep the corresponding valve from fully closing robbing you of power.  If the valve lash is too loose it will also rob you of power by preventing the valve(s) to open to the optimal height and for as long (duration) as designed.  In severe cases it can even cause push rod or rocker stud failure.  
• Things to know:
• A how-to video on the subject can be found HERE.
• During your initial break-in period (first hour of use) valve lash will change.  This is a natural byproduct of heat cycling which relieves component stresses from the manufacturing process.  In the case of our engines valve lash will initially increase.  After the first hour of use valve lash should be reset.
• We always recommend checking your valve train on a regular basis.  As racers ourselves, we make it part of our weekly check.  After initial break-in lash typically does not change BUT it is a simple check to insure you are at optimal power.
• Hint:  Set your valve lash, both intake and exhaust COLD, at .001”.  This IS less then what is commonly recommended but our valve lash will expand when the engine is brought up to operating temperature.

 

• Clutch installation – There are many different philosophies that are taught when it comes to clutch installation.  Forget what you might have used on other engines.  ALL Briggs & Stratton racing engines REQUIRE that the clutch be locked on the crankshaft using a correct radius washer.  Neglecting to lock the clutch down on the crankshaft will lead to the keyway pounding until FAILURE.  The Briggs & Stratton racing crankshaft is designed with a radius in the transition from the output shaft to the larger step at the bearing pocket for increased strength. Neglecting to use a proper radius washer (available from your clutch supplier and included with most clutches) that matched this contour or substituting a standard washer could cause damage to the radius of the crankshaft when tightened.

• Things to know:
• A video on properly clutch assembly, what a radius washer looks like, and the damage from not following our recommendations is located HERE.

 

• Fastener torque – Checking critical fastener torque every time you race is a simple way to prevent issues from happening.  Although our racing engines are designed from materials to fasteners to gaskets to handle the stresses and harmonics that the racing environment brings there are impacts beyond our engineering control that can and will impact torque retention.  A clutch or tire out of balance, a rough track, running an engine lean (raising material temperatures) are examples of situations that adversely affect materials (accelerated expansion) or bring harmful harmonics back through the engine.  Every vibration ultimately ‘feeds’ back through your engine.
• Things to know:  

• Critical fasteners should be checked before and during a race event.  Again, this is simple, preventive maintenance.

• Critical fasteners that we recommend looking your engine over regularly:

• Head and side cover bolts.
• Exhaust system (aftermarket) - These systems are heavy and if allowed to loosen will break or strip exhaust studs/bolts. We do not recommend using a graph-oil exhaust gasket for these systems.  The weight can cause gasket ‘crush’ allowing fastener torque to change.

 

• Fasteners are engineered for specific torque setting.  Going beyond or below factory recommendations inhibits the fasteners ability to stretch as designed to retain torque.
• A short video on setting torque is available HERE.
• Recommended fastener torque can be found HERE.
• Fastener torque should be checked while the engine is COLD.
• Manufacturer torque recommendations are at ambient temperature.

 

• Fuel Filter – We strongly recommend running a 40-75 micron fuel filter to prevent contaminants from your fuel system from entering your engine.  Contaminants allowed to enter into the carburetor can clog jets or fuel passages altering your carburetor calibration and engine performance.  A 40 micron filter, part number 691035 is available through your source of supply.

By following this guide and increasing your overall product knowledge you increase your control over what happens at the track.  Knowledge is power.  Racing is about competition but don’t hesitate to ask other racers or contact anyone of our racing dealers to ask questions.  A simple question, which we all have asked ourselves at one time, can make all the difference.