Northern Lights — Adjusting Valve Clearances
Adjustments · valve train
From a Northern Lights owner's manual covering: L439, L668, M40C, M439, M445, M65C, M668, M99C. Check it applies to your exact model before use.
Applies to: Northern Lights M668
Before you start
- Check clearances after first 600 hours, first 1200 hours and every 1200 hours thereafter.
Procedure
- Remove rocker arm cover with ventilator tube.
- Remove plastic plugs from engine timing holes on front of flywheel.
- Rotate flywheel clockwise with Flywheel Turning Tool until Timing Pin engages timing hole.
- Position No.1 piston at TDC on compression stroke.
- Adjust valves marked with X; rotate crankshaft one revolution to bring No.4 (or No.6) to TDC.
- Adjust valves marked with O.
- Insert feeler gauge between valve stem and rocker arm and adjust with screw until slight drag.
Tools required
Tool links are Amazon searches (affiliate links); manufacturer special tools may only be available from a dealer.
Specs & values
- Intake 0.014 in. (0.35 mm)
- Exhaust 0.018 in. (0.45 mm)
Full service-parts list: Northern Lights M668 →
Source: Northern Lights owner's manual. Steps and values are as documented; always cross-check against the official manual and any later revisions for your exact serial number before servicing.