Start Small Gas Engine Measurements Tips for a

Start….

Small Gas Engine Measurements Tips for a Smooth Rebuilding Process

Outline • Introduction to tools • How to use tools • What areas to measure • How to measure

Tool Types Micrometer Telescoping Gauge Gap Gauge Feeler Gauge Caliper Gauge Ruler

Micrometers • Reading a micrometer • Use two 90 degree measurements for round surfaces • Is used with other tools • Areas to use for small gas engines – Journal measurements for crankshaft – Cylinder measurements – Piston measurements

Feeler and Gap Gauges • Gap gauges are used to measure spark plug gap • Feeler gauges are used in making extremely thin measurements • Use a feeler gauge – Ring measurements – Ignition point gap – Valve tappet clearance

Measurements to Check • • Compression check Spark plug gap Ignition point gap Armature air gap Crankshaft Cylinder Piston and rings More. . .

• Valve and tappet clearance • Carburetor float height

Compression Check • Two main ways to check compression – Using a compression gauge – Rotating the flywheel the wrong direction in

Spark Plug Gap • Check condition of spark plug first • Use a Gap Gauge • Check engine manual for specs Gap

Ignition Point Gap • • Use a feeler gauge to check Check manual for specs Adjust size of gap as needed Make sure points hit squarely Adjustment screw

Armature Air Gap • Use a thick piece of paper or normal cardboard to measure • To adjust loosen screws on sides and slide up or down as needed Adjustment Screws Air Gap Flywheel

Crankshaft • Use micrometer to measure • Compare results to manual specs • Get journal measurements for – Drive end – Connecting rod – Magneto end

Crankshaft Connecting Rod Journal Drive End Journal Magneto End Journal

Cylinder • Use a telescoping gauge or an inside caliper gauge with a micrometer • See engine manual for specs • Check more than one depth – Top, center, and bottom of travel – Most wear will occur at the top due to ring travel – Make sure to check each depth twice at 90 degrees to the first

Piston and Rings • For the piston use a micrometer • Take measurements at top, bottom, and skirt of piston • Compare results to manual specs More. . .

…Rings • Use a feeler gauge for all ring measurements • Check ring side clearance with rings in piston ring grooves • Remove rings for end gap measurements • Use piston to evenly place rings inside cylinder for measurements More. . .

…. Rings • Remove and replace rings carefully with a ring expander • Compare results to manual specs

Valve and Tappet Clearance • Make measurements with a feeler gauge • Check results against engine manual specs • Make measurements while the valves are closed

Carburetor Float Height • Measure float height with a ruler • Check manual for suggested height • Adjust height to acquire the correct fuel intake

Summary • Introduction to tools • How to use tools • What areas to measure • How to measure

The End