Valve adjustment is one of the most overlooked—but essential—maintenance tasks for the Honda Acty, especially on older models like the HA3 and HA4 with the carbureted E05A engine, and the HA6/HA7 with the fuel-injected E07Z. If your Acty is running rough, making ticking noises, or feeling sluggish, incorrect valve clearance might be the culprit.

🧠 What Is a Valve Adjustment and Why Does It Matter? Your Acty’s engine uses rocker arms to open and close intake and exhaust valves at precise times. Over time, the clearance (or "lash") between the rocker arm and valve stem can increase or decrease due to wear and heat cycles. If the lash is too tight, the valves may not fully close, causing compression loss or burnt valves. Too loose, and you’ll get noisy tapping and poor fuel economy or performance.

A proper valve adjustment ensures your valves are opening and closing exactly when they should, which improves:

Engine smoothness and idle

Fuel efficiency

Cold starting

Long-term durability

🛠 When Should You Adjust the Valves? Honda recommends adjusting valve clearances every 20,000–30,000 km (12,000–18,000 miles), or anytime you notice:

Ticking/tapping noises from the top end

Loss of power or throttle response

Rough or unstable idle

Hard starting when cold

You’re already doing a timing belt or spark plug service

🔧 Tools You’ll Need Feeler gauges (metric)

10mm wrench

Flathead screwdriver

Socket set (to remove valve cover)

Torque wrench (optional, for valve cover bolts)

Valve cover gasket (optional but recommended)

Clean rag and degreaser

💡 For E05A engines, typical clearance specs are:

Intake: 0.15 mm

Exhaust: 0.20 mm (always check your service manual)

🔄 How to Perform a Valve Adjustment (Step-by-Step)

1. Let the Engine Cool Valve lash must be set on a completely cold engine—ideally, one that hasn’t run in at least 4–5 hours.

2. Remove the Valve Cover Disconnect the battery.

Remove spark plug wires and any breather hoses connected to the valve cover.

Unbolt and lift off the valve cover. Use a new gasket if needed.

3. Rotate Engine to Top Dead Center (TDC) Use a ratchet on the crankshaft pulley bolt to rotate the engine clockwise.

Align the timing mark to TDC for cylinder #1.

Make sure both intake and exhaust rocker arms on cylinder #1 are loose (valves closed).

4. Measure and Adjust Valve Clearance Slide the correct-size feeler gauge between the rocker arm and valve stem.

Loosen the lock nut, turn the adjuster screw until the gauge slides with slight drag.

Hold the adjuster steady while tightening the lock nut.

Recheck the clearance after tightening.

5. Repeat for Remaining Cylinders Rotate the engine 120°–180° each time to move to the next cylinder's TDC.

Repeat the process for all intake and exhaust valves.

6. Reassemble and Test Reinstall the valve cover and hoses.

Reconnect the spark plug wires and battery.

Start the engine and listen—it should idle smoother and more quietly.

✅ Final Tips Double-check clearances after tightening each nut

Don’t overtighten the valve cover bolts—they’re easy to strip

Combine this service with a spark plug or timing belt replacement for efficiency

If your engine still runs poorly after adjustment, check for vacuum leaks, carb/EFI issues, or ignition problems

📦 Looking for a Valve Adjustment Kit? We offer Honda Acty service bundles with:

Feeler gauges

Valve cover gasket

Spark plugs

Timing tools

👉 Browse Valve Adjustment Kits or contact us with your chassis code for model-specific help.