G'day folks,
Due to the cam design, so as to incorporate ACR as AVB says, compression gauges are of no real diagnostic use on these Briggs engines.
'Easy Spin starting' is old technology now, and Briggs no longer have any detailed docos on their website describing it. You have to go to an older print edition shop manual for that - even the current Briggs CE8069 'Repairman's Handbook' manual omits it.
The excerpt which follows is taken from the 1981 edition of B&S' 'Service And Repair Instructions'.
The intake lobe on the camshaft is ground with a small ramp which holds the intake valve open 1/100 of an inch for a tiny fraction of the compression stroke. At slow starting speed the interval of time that the valve is open is relatively long and therefore enough air escapes to noticeably reduce the compression. However, at operating speeds the interval of time is so short that there is practically no escape and therefore horsepower is unimpaired. Actually at 3600rpm the valve is opened for a mere 1/200 of a second. In all other respects the valves operate as in any other four stroke cycle engine.
The force required to start an engine is reduced by 50% with 'Easy Spin' and would be noticed most by a person who has difficulty starting the ordinary engine.
Briggs have gone away from Easy Spin due to its making hot starts, particularly after the engine has been stalled, more difficult.
