Engine Model:
Briggs & Stratton
Classic,
450 and 500 Series
Page
11 of 32 B&S Classic, 450 and 500 Series Selfhelp
Guide 2011, Issue 1.0
A: Spark Plug:
Check the H.T. lead (1 in the diagram) is correctly fitted to
the spark plug.
To check the state of the plug, u
nscrew the spark plug (2 in
the diagram) with a genuine spark plug spanner. Oil can be
cleaned from it (the result of the machine having been
overfilled with oil or tipped incorrectly) with a clean rag.
A wire brush or emery paper can be used to clean any
carbon deposit from the plug.
Whilst the plug is removed, prime the engine 10 times and
pull the recoil rope 6 times. This will rinse and eject any
residue of oil from within the cylinder head.
Now it would be prudent to check the air filter:
1. The filter is above the primer bulb. It is secured with a
long silver screw (flat bladed screwdriver required).
Remove this screw and gently wriggle the air filter
cartridge upwards and clear from the engine (you do not
need to remove the top plastic engine cover).
2. Split the two halves of the air filter unit and remove the
foam from within. If very oily, squeeze the sponge into
some kitchen roll to remove any excess oil. Then, clean
the sponge in hot soapy water, Dry it thoroughly, then
work one tablespoon of oil into the sponge so that it is
sticky to the touch. Re-install the air filter.
3. The air filter should be checked and maintained once a
month during the cutting season (especially if the weather
is unusually warm) because the foam could dry out.
If you wish to test for a spark
(2 people required):
1. Stand the machine on a firm surface and set the height adjusters to the lowest
setting for added safety.
2. Remove the H.T. lead – a push fit.
3. Unscrew the spark plug with a genuine spark plug spanner.
4. Fit the plug back into the end of the H.T. lead and rest it against the engine block
(hold only the black insulation lead).
5. The second person can now hold in the Operator Presence Control and pull the
engine cord. You should see a spark jump across the end of the plug.
The spark plug gap should be 0.76mm or 0.03” (
30
/
1000
).
Replace the plug and ensure the H.T. lead is correctly fitted to the spark plug.
NOTE: If there is no spark, change the plug. If there is still no spark
refer to a service dealer because the coil may be faulty.
