Briggs & Stratton Racing Engines


As the racing season is winding down it’s important to take a few extra minutes to prevent unnecessary costs and headaches down the road.  Engine storage has changed dramatically with the introduction of ethanol in our fuels.  Even the oil you store your engine with can lead to severe engine damage. 

Ethanol in today’s formulated gasoline and methanol fuels both attract water and react with a wide range of materials if left exposed to for extended periods of time.  Water leads to the formation of rust which can accelerate engine damage, especially upon initial restart.  The reactive nature of these fuels cause oxidation, varnishing, and hardening of rubber and gasket materials within weeks.  The only way to prevent potential issues is to purge and protect your entire fuel system. 

The BEST solution for proper storage is to completely drain fuel your fuel system starting at the tank. 

CAUTION: Do not run any engine in a closed environment. Fuel and fuel vapors are extremely flammable and explosive. Use only approved containers and always use proper precautions when working with fuel.

  1. Start by draining both the tank and the fuel line from the fuel pump inlet back to the tank.  An automotive evacuator is the easiest solution.   Alternatively, with the vehicle elevated the disconnected fuel line can be lowered into an approved fuel can and slight air pressure in the vent hose can be used to start a natural siphon. 
  2. Once the tank and inlet fuel line have been drained the engine can be ran until fuel in the fuel pump feed into the carburetor and the float bowl itself are empty. 

(An alternative method if running the engine is not possible- Drain the line from the pump outlet to the carburetor bowl itself by opening the carburetor drain screw on the side of carburetor bowl allowing it to purge into an approved fuel can through the black drain line/hose on the bowl.)

  1. Once the engine runs out of fuel feed the rubber drain line into an approved fuel container and open the drain by turning the drain screw counter clockwise.  If you used the alternative draining method leave the drain line feed into the fuel container.
  2. While the bowl drain is still open, take WD-40 and through the inlet fuel (where your fuel line feeds into the carburetor) allow a slow spray to feed into feed.  Continue until WD-40 is visibly draining into your fuel container.  This will give your carburetor a protective barrier against any residual fuel.
  3. If you are using Briggs 4T synthetic oil and it is relatively new (free from the possibility of fuel contamination) the rust inhibitor makes for a perfect long term storage option and you are done until the season starts again.
  4. If you are using a ‘karting’ oil, in general these are PAG-based products.  PAG ‘oils’ are hydroscopic in nature (attract water) and have a low solubility preventing the proper suspension of additives that could help prevent rust and acid formation. 

PAG oils accelerate the formation of rust and when combustion by-products (almost certain) mixes with the water this oil base turn into a mild acid is formed further increasing the likelihood of engine damage.

PAG based karting oils left in the engine over winter will cause rust to form on your cam, crankshaft, piston rings, and lower cast iron sleeve.  

  • PAG oils at a very minimum should be drained from the engine and a standard automotive oil or Briggs 4T be used for protection.
  • CAUTION:  PAG-based ‘karting’ oils are NOT compatible with any other oil base so it is important that storage oil be flushed completely out and replaced before starting.  Failure to do so and the incompatibility of PAG oils can lead to engine damage or failure.
  • If you are looking to switch from a PAG-based karting oil to Briggs 4T we recommend that your crankcase be completely purged as PAGS are not compatible with any other synthetic oil base. 
  1.  Store in a DRY environment.