Very loose valve and or over tight valve will give low readings too try this 1st
and than do a wet compression test as add adding a bit of oil in the cylinder and than do the compression test
1. Rotate engine until No. 1 piston is on TDC of compression stroke. Loosen rocker arm adjusting nut until lash is present.
2. Tighten adjusting nut until lash is removed. Tighten adjusting nut one full turn. Adjust remaining valves (for piston at TDC) as listed below
3. Rotate crankshaft 360 degrees to bring No. 4 piston to TDC of compression stroke. Adjust remaining valves.
Piston At TDC Intake Exhaust
********No. 1 No. 1, 2 & 3 No. 1, 5 & 6
********No. 4 No. 4, 5 & 6 No. 2, 3 & 4
Monday, March 16th, 2009 AT 6:21 AM