Honda Lawnmower Servicing Guide

Is Your Honda Lawnmower Not Performing? Time for a Service!

Honda lawnmowers are renowned for their durability and longevity, often outlasting their owners with proper care. If you're wondering whether your trusty Honda needs a new air filter or a more comprehensive service, the answer is likely that a well-maintained mower will always perform better. This guide will walk you through the essential maintenance steps for common Honda GCV 135 and GCV 160 engines, ensuring your mower starts easily, runs smoothly, and cuts effectively for years to come. We'll cover everything from basic checks to more involved procedures, empowering you to keep your Honda in peak condition.

Essential Checks: Fuel Tap and Spark Plug

The first step in any service is to ensure you're working safely. Honda lawnmowers are fitted with a convenient fuel tap. Turn this to the vertical position to stop the fuel flow. Next, disconnect the spark plug lead and carefully remove the spark plug. For GCV 135 and 160 engines, the recommended spark plug is the NGK Spark Plug BPR6ES. Ensure the spark plug gap is set correctly between 0.7 to 0.8mm (0.028 to 0.032 inches). It's good practice to leave the spark plug removed throughout the servicing process to prevent accidental starting.

Draining Fluids: Oil and Fuel

To avoid messy spills and potential starting issues caused by tipped oil and fuel, using an oil extractor is highly recommended. An extractor pump allows you to safely remove all oil and fuel without tipping the mower. This also provides a clean and efficient way to store the fluids for environmentally friendly disposal. The Pela 6000 Oil Pump is a popular and effective choice for this task.

Accessing Key Components: Removing the Starter Recoil

With the spark plug out and fluids drained, you can now remove the starter recoil cover. This not only gives you access to replace a frayed starter rope but also provides much better access to the carburettor and other internal components. Typically, this involves removing three nuts on the top of the cover. It's also a good time to remove the fuel tank, any surrounding plastic parts, and importantly, the air filter. Leave all covers removed until the service is complete to ensure you have unimpeded access to all areas.

Replacing the Starter Recoil Rope

Inspect the starter recoil rope for any signs of wear or fraying. If it needs replacing, pull the rope out as far as it will go and use a clamp to hold the recoil mechanism under tension. Carefully remove the old rope. Cut a new 3.5mm starter rope slightly longer than the original. Burning the ends of the new rope will prevent fraying and make it easier to thread. Line up the holes on the recoil and feed the new rope through. Tie a secure knot at the end, ensuring it's tight. Do not release the clamp yet. Burn the other end of the rope and attach a new starter handle. Slowly release the clamp, allowing the spring to wind the rope evenly. Pay attention to the video demonstrations for a visual guide.

Keeping Cool: Cleaning the Cooling Fins

With the starter recoil and housing removed, take the opportunity to clear any debris from the engine's cooling fins. Blocked cooling fins can lead to overheating, causing the engine to start and then die shortly after. A good blast of compressed air is usually sufficient to clear out accumulated dirt and grass clippings.

The Heart of Performance: Servicing the Carburettor

Servicing the carburettor might seem daunting at first, but with a little practice, it's a straightforward process. After removing the air filter housing (usually held by three bolts), the carburettor will drop down. It's crucial to take photos of all springs and linkages connected to the carburettor before disconnecting them. Unhook the governor linkages and any springs, potentially by loosening the central bolt on the control arm. Disconnect the fuel line and place the carburettor in a small tub to catch any residual fuel. Remove the bowl from the bottom of the carburettor (typically with a 10mm spanner), noting the gasket between the bowl and the carburettor – replace it if damaged. Remove the float and its retaining pin, being careful not to lose the small needle that drops out. Unscrew the main jet using a thin flathead screwdriver. If it's stuck, a small Allen key can be used to push it out from the top. The main jet often consists of two pieces. Clean all tiny holes in the jet and carburettor with carburettor cleaner spray and compressed air. Blocked jets are a common cause of starting and idling problems. Clean all other parts of the carburettor thoroughly. Reassemble, ensuring the needle and float are correctly seated, and the bowl is re-tightened carefully by hand to avoid cross-threading. Reconnect the fuel line and check for leaks with the fuel tap open, ensuring the needle is properly seated.

Reassembly: Putting it Back Together

When refitting the carburettor, reconnect the linkages, ensuring the spring goes to the furthest hole and the longer linkage to the nearer hole. A smaller linkage will also connect to the side of the carburettor. Align the carburettor with the engine, ensuring gaskets and holes are correctly positioned. Reattach the air filter box, starting with one long screw through the box, gaskets, and into the engine. Tighten evenly, remembering to reconnect the rubber breather pipe to the back of the air filter box. Patience is key here; you may need assistance to hold components in place. Fit a new air filter if required.

Replacing the Air Filter

After servicing the carburettor, it’s essential to fit a new air filter. If you choose not to replace it, thoroughly clean the old one with compressed air. Preventing dirt from entering the clean carburettor is paramount.

Ensuring Smooth Running: Adjusting the Valves

If your Honda lawnmower is difficult to pull over or runs unevenly, especially at lower speeds, the valves may need adjustment. While carburettor servicing often resolves these issues, valve adjustment is crucial for optimal performance. Honda GCV 135 and 160 engines have overhead valves (OHV) that require periodic adjustment. Carefully remove the valve cover. With the spark plug removed, insert a plastic screwdriver into the spark plug hole and turn the flywheel to find Top Dead Centre (TDC). At TDC, one valve will be fully open, and the other fully closed. Use a feeler gauge to check the clearance: Inlet valve should be 0.006 inches +/- 0.016 inches, and the exhaust valve should be 0.008 inches +/- 0.002 inches. Adjust by loosening the locking nut and turning the adjuster. Ensure the locking nut is tightened carefully. Correct valve clearance makes a significant difference to starting ease and engine smoothness. Replace the valve cover, using gasket sealant if necessary. The flywheel should now turn with a more even resistance.

Setting the Ignition Coil Air Gap

While not always necessary, if components have been disturbed, checking the ignition coil air gap is important. The correct gap between the ignition coil and flywheel on GCV 135/160 engines is 0.254mm to 0.355mm (0.010 to 0.002 inches). A piece of an old greetings card or a playing card can be used to set this gap. Turn the flywheel so the magnets are away from the coil, loosen the coil mounting bolts, insert the card, and turn the flywheel until the magnets attract the coil against the card. Tighten the bolts, then remove the card. This ensures an even gap.

Blade Care: Removing and Sharpening

With the spark plug removed and fluids drained, tip the mower with the carburettor facing up. Use a 13mm socket to remove the two bolts holding the blade. For best results, have the blade professionally sharpened. If sharpening yourself, use a file or bench grinder, maintaining the correct angle for back lift. A blade balancing tool is essential to prevent vibration. Consider replacing the blade if it's significantly worn or damaged.

Drive System Health: Checking the Self-Drive Belt

With the blade removed, it’s a good time to remove the belt guard and clear out any debris. Accumulated debris can dislodge the drive belt, potentially causing damage. Inspect the belt for wear and replace it if necessary.

Deck Protection: Cleaning and Painting

A clean cutting deck prevents premature rust. Use a wire brush, scraper, or pressure washer to remove grass build-up from the underside. Painting the underside with a rust-resistant paint like Hammerite will significantly extend the deck’s life. Avoid cutting wet grass, and utilise any self-cleaning features your mower may have.

Safety First: Checking the Microswitch

Most Honda mowers use a microswitch for safety, which must be activated for the engine to run. Pull the safety lever and check that the microswitch moves freely and is fully engaged. A partially engaged lever can prevent the engine from starting.

Automatic Choke Operation

Honda's automatic choke system eliminates the need for manual priming. If your mower is hard to start, the choke mechanism might need adjustment. With the air filter removed, observe the choke butterfly valve in the carburettor. It should be fully closed when the throttle is set to 'choke' and fully open at 'full speed'. Adjust the throttle cable to ensure the butterfly operates correctly. A faulty choke or microswitch are common culprits for starting issues.

Technical Specifications Summary

Troubleshooting: Checking the Flywheel Key

If you experience kickback after servicing, check the flywheel key. A damaged key significantly alters ignition timing. Remove the starter recoil covers to access the flywheel. Use a flywheel puller to remove it and inspect the key for any damage or imperfections. Replace the key if necessary, as it dictates the spark plug's firing timing.

Sourcing Parts and Final Thoughts

When purchasing spare parts, always use genuine Honda parts or high-quality equivalents. Aftermarket parts can often cause more problems than they solve. Locate the service sticker on your mower for the correct model and serial number, which is essential for sourcing the right parts. Take a photo of this sticker for your records. With regular servicing and attention to these key areas, your Honda lawnmower will provide reliable service for many years. Remember, a well-maintained machine is a pleasure to use!

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