PLEASE NOTE, THIS REVIEW IS IN THE PROCESS OF BEING WRITTEN AND ADDED TO, ONLY WHEN I HAVE A MOMENT TO DO SO. THIS REVIEW IS A LONG WAY FROM BEING COMPLETE AND I HAVE ONLY PUT IT UP IN THIS STATE SO THAT IF YOU ARE THINKING OF ONE OF THESE MACHINES YOU CAN HAVE A MUCH CLOSER LOOK AT IT WITH THE PHOTOS THAT ARE UP NOW.
YOU SHOULD COME BACK AT A LATER DATE TO SEE THE COMPLETE REVIEW WHEN THIS MESSAGE HAS BEEN REMOVED. I WILL GOING INTO MUCH GREATER DETAIL ON EVERY PART OF THIS MACHINE AND FINALLY GIVING FOR MY PERSONAL OPINION ON IT FOR WHAT IT IS WORTH.
MY PERSONAL OPINION, IF YOU ARE LOOKING FOR A MACHINE IN THE 35cc CLASS, THIS IS A GREAT MACHINE, BUT NOT PERFECT.
In Australia, this model is called the UMK435U, it may go by other descriptions in other country.
This Honda 4-stroke brush cutter has been around, pretty much unchanged since at least 1997. These first brush cutters were then powered by either a GX22, or GX31 push rod overhead valve engines. In 2002, the GX22 was upgrades to the GX25. This new engine with a belt driven overhead cam was lighter and more powerful than it predecessor. The GX31 was similarly upgraded to the GX35 in 2003, again reported to be lighter and more powerful and supposedly with less vibration and noise.
Both the GX25 and GX35 comes in either loop handle and bicycle handle variants, but this review is of the loop hand machine.
It also seems that not all Honda’s are equal, depending on what country you live in.
The US version. Look closely and you will see that the gearhead, clutch housing, hitch and loop handle are all different to the Australian version. The aluminium shaft O.D. is 25.4mm (1″) and power is transmitted down the shaft using a flexible drive shaft.
I am not convinced that a flexible shaft is really up to the punishment, that is fed back up the shaft when pushing a metal blade hard and I am not really sure what a limited lifetime warranty means. When I find out, I will add this information here.
Below is what they say in Honda’s US brochure.
Honda’s flex shaft design is lighter, stronger, and has a longer life than a solid type of shaft. In fact, it offers the strongest torsional strength in the industry, as well as longer life through the ability to absorb shock. It’s much easier to service. And the flex shaft offers all of these benefits without increasing vibration or operator fatigue. We’re so confident in the performance and durability of our flex shaft, we back it with a limited lifetime warranty.
Not sure what a limited lifetime warranty really means, so if you are someone who lives in the United States and knows what the limited lifetime warranty entails, please let me know.
The UK & New Zealand version, is different again, the gearhead looks similar to the Australian gearhead, but a little bit different again. The biggest difference is the clutch housing, which looks very different and more modern. Both the trigger control handle and the loop handle also have a soft rubber grip.
As you can see in the photo on the left, the loop handle is also angled like the Husqvarna. I think as time goes by, this will become common to all loop handles. All in all, a much more modern looking machine. Perhaps this is the new updated machine and that these new features may find there way to Australian Honda’s. If not, I will be wanting to know why.
As yet, I have not been able to find out the diameter of the drive shaft, but I suspect that it will be 7mm diameter. Honda UK does say that it has a 6 spline drive connection, at least to the clutch housing. As yet, not sure about the connection to the gearhead. They also state that, these engines are easy to start, because they have a super light flywheel. In my books, a lighter flywheel means you have to pull the engine over faster to give the inertia to keep the engine running, so one of us must be wrong. My first second generation engine, use to always take two pulls to start it, but I just thought that it was just some fine tuning issues with that engine. After having owned three GEN-2 engines now and found that they all take at least two pulls to start, I am convinced that a lighter flywheel is the cause of this issue.
What is great about this brush cutter
In my opinion, this is the best best small engine fitted to any brush cutter, PERIOD. It is leaps and bounds ahead of any 2 stroke engine and I think still ahead of the growing number of 4 stroke engine finding there way on the market as I new they would.
This is Honda’s second generation engine, going from a push rod driven overhead valves, GX22 and GX31, to a belt drive single overhead cam driven valve, GX25 and GX35. These second generations engines are more powerful and lighter, but unfortunately this comes at a cost. Even though this engine is a marvel of engineering, I was also a little disappointed with it. I always thought that this engine was a little noisier, seem to vibrate a little more and the three GX35 engine I have owned, none of them almost never start with the first pull. They all take at least two, sometimes three pulls to start. Whereas the first generation engine I owned, always started on the first pull.
It wasn’t until I found this graph below that proved my suspicions. The X value is horizontal engine vibration, the Y value is the lateral vibration up and down the shaft and the Z value is vertical engine vibration. It you compare the X Y Z figures for the GX31 and GX35, you will see that this second generation does produce more vibration.
I suspect that this is because of the engine being lighter and with less mass is more affected by the reciprocation action of the piston. The engine weight savings, probably comes from a number of small weight savings. The aluminium engine block being lighter would result in more vibration, the muffler being a little smaller and lighter would result in more noise and a lighter flywheel would mean a faster pull speed is required to start the engine. Air cooled engines are noisier by design, as the cooling fins resonate, transferring combustion noise to the air cooling the engine and thinner fins could resinate more than thicker fins. Of cause I no longer own a first generation engine to prove this, but if you happen to own one of these older GX31 engine brush cutters that you no longer need and live in Australia. I would pay the shipping to get my hands on one to pull apart to inspect and weigh all the parts. If this is you, please send me an email;
I do not want to compare the difference between the Gen 1 & 2 engines to criticise Honda for their design choices. But to further my own knowledge of how weight of components affect vibration of those components, as it is very hard to find this kind of information online relating to small engines.
Of cause I know why Honda wanted to reduce the weight and that is because of a lot of the early feed back and reviews went on about how heavy the engine was compared to a 2 stroke engine. I had the same problem with vibration, when I went to make my BrushDestructor blade lighter. Making anything mechanical, lighter comes at a cost.
Despite all this, I still think the Honda engine, is still the best brush cutter engine in the world and you will not go wrong owning this 4 stroke brush cutter.
35.8cc, 4 stroke, belt driven overhead cam engine, with a unique form of engine lubrication that allows this engine to run any way up.
This engine produces a net power output of
1.0 kW (1.3 Horse Power) at 7,000 rpm
and a net torque of
1.6 Newton meters (1.2 foot-pounds) at 5,500 rpm
A compression rate of 8 to 1
An oil capacity of 0.1 litre (0.21 US Pints)
A diaphragm type carburettor
and transistorised ignition magneto.
The Cooling air is produced by a centrifugal fan, that is also a flywheel and clutch drive and like all brush cutter engines the cooling air is directed by a cowling around the cylinder cooling fins.
Some of the air going over the top of the engine, is directed out past the muffler to help keep that cool as well. This design is pretty much typical to all small air cooled engines.
Below is a couple of views of the Honda GX35 muffler and as you can see comes standard with a screw on spark arrester. This 35cc engine, is probably the quietest engine for its size fitted to any brush cutter, but even so, I think Honda could have made it still quieter if they had really wanted to.
Personally I am not convinced that a spark arrester is necessary on brush cutter, because of the operating height of the engine from the ground and the fact that a metal blade produces far more sparks than you would ever get out of 4 stroke engine. I was once out after dark, trying to get a job finished and was stunned how many sparks come off the metal blade. You only have to hit dust imbedded in the bark of a tree or lightly nick a stone and the shower of sparks that come off would equal that of an angle grinder. For this reason I would never recommend using a brush cutter on a total fire ban day. A well designed muffler with more compartments, would probably do the same job, without adding a fine mesh to the tail pipe that can clog up. I tried operating the engine without the arrester, but it made it noisier, especially when throttling down, so I put it back.
I have also read on many forums, of people complaining about the engine lacking power or no longer able to reach full revs and one of the possible caused for this problem is a blocked spark arrester.
Above is the the muffler from the Chinese copy Honda which I cut apart, to see what it looked like inside. I also noticed that this muffler did not have a spark arrester. So the Chinese may have copied this muffler before Honda started fitting a spark arresters to their genuine engines.
Carburettor & Air Filter
Below is a close up picture of a new clutch and one that has done 187 hours, which might not sound like a lot, but it is. I should add that the engine on the right is the same engine that has done all the testing and development of the Model-17 blade and has probably been subjected to more extreme shock loading than probably any other GX35 world wide and is still going strong. See video of extreme testing near the bottom of this page.
As you can see, there is a small amount of wear in the centre of the pads, but almost none to each outer edge. This is due to the slight difference in diameter of the pads to the inside face of the clutch drum and any wear from now on should be much slower.
I think I could safely say the the average person should get in excess of 1000 hours of use from these clutch pads and should last the life of the engine for most users.
This tank has a capacity of 0.65 litres or for the US market, 0.166 US Gallon, or 1.33 US Pints.
The fuel tank is made of a white translucent plastic like all other tanks and is mounted with rubber isolators to help reduce vibration to the tank. This is to helps reduce aeration of the fuel as the tank gets low and so it can drain every last drop of fuel from the tank. However there is one major issue with this tank, if this engine is used on a Loop Handle machine.
See below under, What Is Not So Great About This Brush Cutter for more details.
Below is a close up of the new clutch and vibration isolation housing. This is the first two piece housing that I have seen, that I presume is designed to make it easier to replace the isolating rubber bush.
I had noted earlier on this page, that it looked like there were different versions of clutch housing used in different countries. This parts drawing below, shows that there is a plastic cowling to cover the clutch housing. Why some have this and some don’t, I do not know, it could be as simple as wanting to keep prices down in some countries.
The aluminium shaft here in Australia, has an outside diameter of 26mm and has a 2mm thick wall. But I have read that the aluminium shaft in the United States has an outside diameter of 25.4mm (1″).
In Australia this brush cutter comes with a 7mm diameter solid steel drive shaft and yet for some reason, in the States it apparently has a flexible shaft.
Although this gear head may look like any other gear head, the quality of the materials and engineering would surpass most if not all others. Turning the gears around with your hand, you can just feel how smoothly they turn over and they make no sound. The gears are obviously machines to a very high standard and are place so that they mesh perfectly. The gears are supported on high quality Japanese KOYO bearings and the seals on the outer bearings will keep the high quality Japanese made grease in for many years.
This Honda gear head has a Drive Gear with 15 teeth and a Driven Gear with 20 teeth, giving a gear ratio of 1.33:1 and has a 25.4mm blade mounting arbor.
This means that the engine turns 1.33 revolutions for 1 revolution of the blade, which results in a turn ratio of 4, which is really good for keeping shaft vibration down. Unlike the Echo High Torque Gear Head, which has a turn ratio of of 27 that results in horrendous shaft vibration. Going on Honda’s engineering reputation, I would say that this gear ratio is more by design than chance.
Which is where all these types of brush cutters gets their name from looks solid enough and well shaped. It is a a two piece design, with the loop handle forming the top part and the bottom stick part which clamps the handle to the shaft.
The stick handle is part of the bottom clamping component and so this gives you no option, as to whether you want to use it or not. Now I have been doing serious brush cutting since 1998 when I brought my first Honda. They were not on the early model loop handle brush cutters and to this day I have absolutely no idea as to its purpose. But I am guessing that it must be mandated for some safety reason, as all loop handles come with it now.
The very first thing I would be doing, will be to cut it off, but for liability reasons, I am not recommending that you should do this.
As to this loop handles vibration dampening properties, I would guess that it has fallen way behind what some other manufacturers are offering. I will give more feedback on vibration, after I have used it for several hours.
Trigger Control Handle
The trigger control handle is well finished, but basically unchanged in the last 20 years. This handle is solid bolted to the shaft and offers no vibration isolation to the hand.
Cutting Options & Guards;
In Australia they come with a 4 year domestic warranty, a three year commercial engine warranty, but only give 1 year on the frame.
In the United States, it comes with a 2 year domestic warranty and a 1 year commercial warranty.
The recommended retail price in Australia is AU$789.00 and in the US it is US$379.00. That equals about AU$490.00 which makes it considerably cheaper to buy in the States than in Australia. I cannot quite see how the larger buying power of the US can make quite that difference, but perhaps the extra warranty adds to the price.
What is not so great about this brush cutter
The fuel cap has come loose on a number of occasions on my older genuine Honda. On many occasions I smelt petrol and had to redo the cap up, but on the last occasion the cap had completely vibrated off and I was unaware of this. That is until I smelt petrol at the same time I felt my leg was wet and looked around to find that the contents of almost a full tank had relieved itself all down my leg.
Now a loose cap might not seem like a big issue, but if I had hit a stone to cause a spark that could have ignited all the petrol fumes that now surrounded me, it would have been all over. The overalls I was wearing, were mostly nylon and I would not have had time to remove the harness and overalls before I would have been overcome by the flames. So a petrol cap that comes loose can indeed be life threatening.
After a change of cloths, I went back to find the fuel cap, but finding a black cap in amongst all the mulched saplings proved impossible. After about half an hour of searching, I was almost resigned to the fact that I would have to buy a new fuel cap, when I remembered that I still had the fuel cap from the Chinese copy Honda engine, from the tank I had cut in half to show the fuel pickup issue. When I located this cap, I found that the Chinese cap had a retainer cord, so that you cannot loose the cap.
The finish of the Chinese cap is not as fine genuine Honda cap, but it never comes off and even if it did, the cord would prevent you from loosing it. You can see in the photo below that the Honda powered Husqvarna engine (middle) has a corded cap, but the genuine Honda still does not. If Honda at least made the cap red, it would make it easier to find if it comes off.
It is good to see that Honda has address the fuel pick up issue with the latest Honda’s, by fitting a smaller fuel pickup filter. Looking at the photo below, the new Honda engines on the left have a smaller fuel pickup, as compared to the older Honda on the right that was purchased in 2016 for testing of the new Model-17 blade. If you look closely it has a very large filter that cannot move freely between the side compartments when the brush cutter is turned on its side.
Although this new new smaller filter will move freely between compartments, the soft rubber hose is still not long enough to allow the pickup to reach all corners of the tank which would have completely addressed this issue.
I have just come across this parts drawing, that shows, that there are two lengths of pickup tube. The short length looks like it is for the tank of the horizontal mounted engine and the longer one for the vertical mounted engine. Perhaps the wrong length could be related to wrong tube in wrong tank on assembly, when I get an answer to this, I will update this page.
Guard for Metal Blades
There is a serious problem with the guard meant for metal blades and that is that all the branch cuttings are squeezed through an ever smaller space. Not only horizontally, but vertically as well. This leads to premature failure of the guard when subject to heavy work.
Another big problem, is the socket head bolts that bolt the guard to the gearhead. As you can see in the photo above, they protrude down into the debris clearing area and I personally have had either the heads of the bolts knocked off, or the bolts completely ripped out of the aluminium thread, when a piece of hardwood branch gets squeezed between the guard and blade. I replaced them with dome head socket bolts and loctite them them in place, instead of using the spring lock washers that made them protrude even more and that solved the problem.
Engine Stop Switch
The large red stop switch, is easy to knock and break off especially when you often turn a loop hand brush cutter on its side. I used to often knock the switch off, stopping the engine which was very annoying. I eventually broke mine off against the harness and found that I could not get a replacement. I was told that I had to buy a whole new handle, so I lived without a stop switch for many years and most of the time just kept brush cutting until the fuel ran out. On the odd occasion I had to turn the engine off, I would just turn the choke on and quickly giving it full throttle, this killed it every time.
Ideally the switch needs to be shielded, so that it cannot be broken off, or accidentally turned off. But still easy to quickly switch off with the thumb.
If you would like to leave a comment below, please limit it to this model Honda brush cutter only and word your comments so that they are as constructive and helpful as possible to someone who is investigating the purchase of this machine.
You can agree, or disagree with what I have said here, so long as it is done so in a polite and constructive manor. Or if you own one of these machines then please give your feed back on how you found it worked for you. Good, or bad.
Any comments on this page, not related to this particular brush cutter will be promptly deleted.