I've had a lot of newish Sprinters that don't kick back Norm ,The old Sher drills are awesome ,In 1967 the American Skil Corporation took over Sher Tools Australia, too bad about the drill.
Before you throw a motor out you should take it apart and check the ACR.
I usually just do the easiest tests first for kick back, the following isn't in any order to do, just a list, too much valve clearance ,exhaust valve not opening correctly ,incorrect ignition timing ,coil too close to flywheel ,broken or cracked key on flywheel ,broken key on blade hub , not enough flywheel weight to overcome the compression stroke, spark plug or coil needs replacing ,the automatic compression release is malfunctioning (acr). Don't adjust valve clearance at Top Dead Centre, use proper instructions,restricted or blocked exhaust ,excessively carboned up ,over fueling ,worn rings, bore, piston allowing oil into the combustion chamber, crank case ventilation pumping oil into carby, oil level too high.
