Echo CS-490 Operator's Manual page 11

Unlock chain brake
Proper tension
Direction to tension the chain
Tension adjuster
Improper tension
11
ADJUSTING CHAIN TENSION
IMPORTANT
Always loosen clutch cover nuts before turning
the chain tension adjuster, otherwise the clutch
cover and tensioner will be damaged.
1. Remove spark plug lead. (See page 26)
2. Unlock the chain brake and loosen two clutch
cover nuts, if necessary.
3. Hold the bar nose up, and turn the tension
adjuster clockwise until chain fits snugly against
underside of the bar.
4. Tighten both nuts with the bar nose held up.
5. Pull the chain around the bar by hand. Loosen
the adjustment if you feel tight spots.
6. When chain is properly tensioned, tighten clutch
cover nuts securely - 20 to 23 N·m (200 to 230
kgf·cm).
7. Keep chain properly tensioned at all times.
CS-490