1. Start….

2. Small Gas Engine Measurements
Tips for a Smooth Rebuilding Process

3. Outline Introduction to tools How to use tools What areas to measure
How to measure

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

5. 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

7. 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

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

9. Valve and tappet clearance
Carburetor float height

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

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

12. 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

13. 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
Air Gap
Screws
Flywheel

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

15. Crankshaft Connecting Rod Journal Drive End Journal
Magneto End Journal

16. 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

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

18. Use a feeler gauge for all ring measurements
…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...

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

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

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

22. Summary
Introduction to tools
How to use tools
What areas to measure
How to measure

23. The End