Honda Lawn Mower Self Propelled Slow

There's nothing more frustrating than a slow internet connection, but having to push a slow self drive mower is a close second - DRIVES ME CRAZY!!! 

So it ends now, today we'r going to fix it and it will pull as good as the day you bought it.

So what's the problem with a Honda lawn mower that moves slowly? The problem is a slack drive cable, adjusting the tension will fix it. 

Other possible causes include:

  • Drive belt loose
  • Drive belt worn
  • Worn drive axle
  • Worn out transmission

Don't concern yourself with these other possible causes just yet, they are less likely. We'll get straight to the solving the most likely cause, adjusting the drive cable.

Honda mowers

Self Drive Types

Whichever type you have, the cable will be adjustable.

Adjusting The Drive Cable

I love working on Honda mowers, the designers are a thoughtful bunch. It's rare that an engineer ever thinks about the guy fixing them.

 

Anyway, before adjusting the drive cable, we'll first need to locate it. Honda use a few different type set ups. The HRX use a bail lever as stop/start control and a speed adjustment lever beside to the throttle lever.

 

The Honda Smart Drive uses a single control on the handle bar, this type self drive is a little less difficult to adjust.

 

I have included pictures of each type set up, together with the adjusting procedure. 

 

Mower plug wire Mower gas tap Honda mower on it's side

Disable Mower

For safety, lets remove the plug wire and turn off the gas.

Turn the mower over with the carburettor side facing up, stops gas leaking on the floor.

Adjusting The Honda Smart Drive 

The problem is as you know, likely to be a stretched cable, in other words the cable is too long. The whole procedure is made simple by nice people in Japan, and adjusting won't take more than five minutes.

 

Drive cables are made up of an outer cable and an inner braided cable. The inner braided cable does all the work and stretches over time.

 

The solution is simple, remove the access cable. Honda's solution - fit an adjusting screw in the middle of the cable.

 

The adjuster works by splitting the cable into two and by adjusting the screw anticlockwise, it pushes the two halves of the drive cable away from each other, taking up the slack on inner braided cable.

 

mower bolt damage

Smart Drive

The Smart Drive self propel system has an adjuster built into the cable and it's located half way down the left hand handlebar.

mower engine valves mower engine valves

Adjusting

First open the lock nut, you'll need two open ended 10mm or 3/8s, or adjustable wrenches.

Screw the long adjusting nut anticlockwise - this takes the slack out of the cable and gives you more drive power.

If you over adjust it, you'll find pulling the mower backwards difficult. So just back it off until you find the sweet spot.

Tighten up the lock nut, when your done with the adjusting, this keeps it dialled in.

Adjusting The Hrx

The Hrx has a self drive cable adjusting screw mounted on the speed control panel. As you have turned off the gas and pulled the plug wire, it's safe to turn your mower to the side.

 

Before adjusting, set the speed to high.The adjusting screw has a lock nut which must be loosened and backed off to allow for the cable slack take-up. When adjusting, pull the cable until the cable slack is gone, run in the lock nut and tighten.

 

As with the all self drive mowers, if you overadjust the cable, it will make reversing the mower difficult, the wheels bind. To fix this, back off the adjuster a touch until the mower is free to reverse.

 

You'll need two 10mm or 3/8 wrenches, or adjustable wrenches.

 

mower engine tools mower engine tools mower engine tools mower engine tools mower engine tools

Adjust

  • Set speed to high
  • Loosen lock nut
  • Pull cable
  • Tighten lock nut
  • Test reverse
  • Readjust if necessary

Drive Belt Might Be Loose

Lawn mower drive belts have a difficult job, and they work in a hostile location. But they're pretty tough, it's not unusual for a drive belt to last years and years. 

But they do eventually wear, they stretch and the walls get thinner, which makes them even longer.

 

A belt that's too long will slip, and a slipping belt won't transfer the engine power to the wheels.

 

This is especially noticeable going up hills or in heavy grass. If you have a blade engage control on your Honda you'll really notice it as you apply the blade.

 

A worn belt will often be noisy, and can cause vibration. To check the belt we'll need to turn the mower over, but before we do, lets make it safe to work on. 

Remove the plug wire and turn the gas off.

 

Now turn the mower on it's side with the air filter cover facing the sky. If you turn it up the other way, gas will leak from the carburettor and you'll need to replace the air filter.

 

The belt may be difficult to see, old dry grass will cover the transmission and belt, so we'll need to clear it first. I use shop air to blast it, but a small clean paint brush works too.

 

Now that you can see the belt, check it for wear, you'll need an inspection light. Since you have removed the plug wire, it's safe to turn the blade.

 

This also turns the belt which allows you inspect all the way around it. If your model has a blade engage lever, put it on and have a helper hold it or use a clamp. This allows you turn the belt by turning the blade.

 

If the belt is in good shape check the deflection, I've included a photograph below of a belt that's in good shape, it deflects by about 1/2 inch.

 

But you don't need to get caught up in measurements, just use old fashioned common sense. If it looks really loose and you squeeze both sides of the belt together without much effort, it too loose.

 

mower blade bolt clean

Worn Belt

A worn belt will cause self drive to be slow.

Drive Axle Might Be Worn

The drive axle on a mower is simple really, it should be referred to as a trans-axle though. By trans-axle I mean axle and transmission combined, I wrote a more detailed explanation of trans-axles here for those that are interested (internal link).

 

The axle is connected to and driven by the transmission, these are all one unit and parts are't available, so when they fail, which is pretty rare, you just swap out the whole unit.

 

In addition to the trans-axle and crucial to the whole assembly, is the rear drive wheels and driveshaft pins.

 

The rear wheels are made from plastic and have metal gears on the inside. The gear is driven by the axle metal gear, they wear as the mower ages.

 

Axle drive pins, as their name suggests, is a pin that passes through the axle and drives the metal axle gear. The axle pin is under extreme stress as it's carrying all the torque from the transmission to the wheels, these little guys wear out all the time.

 

Impact tool

Drive Pins

Wear out on older mowers and cause the drive to slip.

Transmission Might Be Worn

Honda transmissions are tough, yes in my workshop I have replace a few, but to be fair to Honda, the mowers were old and driven like a hire car.

 

When your fixing mowers as long as me, you can spot an unloved mower from across the valley.

 

The transmission as you know is a solid state unit, no parts are available, if it fails, the whole unit gets changed out. Replacing the tranny isn't very complex but it will require a selection of wrenches, some c clip pliers and some patience.

 

Impact tool

Tranny

Honda transmissions are pretty good, they rarely fail.

Related Questions

How do you adjust the throttle on a Honda lawn mower? The throttle is controlled by a cable. The cable can be adjusted at the rear of the throttle housing on the handlebars, also on the engine where the cable meets the throttle linkage. 

Honda lawn mower rear wheels locked up? If the drive cable is over adjusted the rear wheels will lock when pulled backwards. Release some tension on the adjuster, it's located half way down the left handlebar.

Auto Technician and Writer at | Website

John Cunningham is an Automotive Technician and writer on Lawnmowerfixed.com. I've been a mechanic for over twenty years, I use my knowledge and experience to write "How to" articles that help fellow gear-heads with all aspects of mechanical repairs, from lawn mowers to classic cars.