4.3.7.1 – Review of Echo SRM420TESU 41cc Bicycle Handle Brush Cutter

Overview

This Echo brush cutter is one of the new breed of top end models, which incorporates the new 2:1 ration gear head and a four point rubber isolated handle bar mount to reduce vibration to the operators hands. This brush cutter is made in Japan by Yamabiko Corporation, who also make the Shindaiwa brush cutters. 

I will spend a few more hours using it and will add more as I learn more about it. I have also ordered a digital rev counter, a sound meter and a single axis vibration meter. When I get these gauges I will test this brush cutter for exhaust noise volume and vibration at the handles from Idle to full revs while under load.

Allpower who were the importers and distributors for Echo and Shindaiwa have gone bust as of July 2018. Briggs and Stratton are the import agents and online sellers of all Echo and Shindaiwa brush cutters for Australian and New Zealand. 

ECHO SRM420TESU 01 (600x327) ECHO SRM420TESU 02 (600x418)

The overall dimensions for this brush cutter is 1852mm long by 680mm wide at the handles and 598mm high to the top of the handles in their normal use position. The total weight, excluding cutting attachment and petrol is 8.7kg.

ECHO SRM420TESU 09 (600x376)


What is great about this brush cutter

Below I will break this brush cutter down into its component parts and look at each part in greater detail. So that you will have a thorough knowledge of this brush cutter, to allow you to make an informed decision if you are considering purchasing one of these machines.

Engine

Type;

Is a 41.5cc, 2 stroke, single cylinder, fan forced air cooled engine, with the fan in the back drawing air in pass the recoil starter. This I think is a good ideas as the intake is more shielded from wet flying grass and dust than the front or side intake. The maximum rpm of this engine is 10,300, the maximum power output is 1.78 kw at 8500 rpm. At this point in time I have not been able to find the engine torque & at what rpm, is for this engine. I will contact to the manufacturer to see if they can supply me with the power and torque curves for this engine and post it here in the future.

Cooling;

The Cooling air is directed by a cowling crossways through the cylinder cooling veins and out past the muffler to help cool that as well.

ECHO SRM420TESU - Engine cooling 1 (600x473)ECHO SRM420TESU - Engine cooling 2 (600x568)ECHO SRM420TESU - Engine cooling 3 (600x551)

Below you can see a heat resistant shield to ensure radiant heat from the muffler does not radiate heat the fuel tank.

ECHO SRM420TESU - Engine cooling 4 (600x410)

Muffler

The muffler is beautify made and finished, as you would expect from a Japanese made product. You can also see the bolt on deflector, which allows you to unbolt and clean the spark arrester screen.

ECHO SRM420TESU - Muffler 1 (600x544)


 Carburettor & Air Filter

I like the position of the fuel pump, which is easy to see and operate. The choke is also in an easy position to see and operate. The recommended fuel oil ratio is 50:1, and of cause they recommend using Echo/Shindaiwa 2 stroke mix.

ECHO SRM420TESU - Carb & Air Filter 1 (600x378)

This engine comes with a double air filtration system, the first is the typical washable foam filter, in front of a replaceable fibre reinforced paper filter. This filter can also be cleaned with compressed air, so unless you are in an extremely dusty environment, it should probably last the life of the brush cutter.

ECHO SRM420TESU - Carb & Air Filter 2 (600x310)ECHO SRM420TESU - Carb & Air Filter 3 (600x362)

The carburettor is a Walbro diaphragm type that relies on the pulsing pressure and vacuum of the crank case to pump and feed fuel through the jets. If you are interested, CLICK HERE see in much more detail how it works.

ECHO SRM420TESU - Carb & Air Filter 4 (600x297)


 Petrol Tank

The moulding of the fuel tank is to a very high standard, the cap seals well and does not leak any petrol even when up side down.

ECHO SRM420TESU - Fuel tank 1ECHO SRM420TESU - Fuel tank 2

The weighted fuel filter is on a long flexible hose and there is no restriction that prevents the pick-up from moving anywhere around the tank. Not so important on this brush cutter, but essential on the loop handle model that can be frequently run on its side.

ECHO SRM420TESU - Fuel tank 4

The plastic tank comes with four very well made vibration isolation supports to reduce vibration to the petrol tank.

ECHO SRM420TESU - Fuel tank 5


Shaft

The outer shaft is 28mm O.D. x 2mm thick aluminium tube with an overall length of (to Check)mm. The drive shaft will probably be 8mm solid steel shaft. (will check this and update).This drive shaft is supported by ?? rubber isolating bush supports.


Hitch

Below is the hitch for this brush cutter, which is limited to 7 fixed points. 

ECHO SRM420TESU - Hitch 1 (600x205)

The different hitch points are to allow enough adjustment for the different weight between a nylon head and a metal blade and to allow for some adjustment for operators of different heights.


Handles & Vibration Isolation

The main reason why I chose to get this brush cutter, is the four point vibration isolation mounts to isolate vibration from the handles and of cause the transfer of vibration to the hands. If you have not yet read this page on vibration and affects on the body, please read this here.

ECHO SRM420TESU - Engine cooling 1 (600x436)

The manual states that the vibrations levels, are measured in compliance with (ISO 22867). They are 2.8m/s² for the left handle and 2.3m/s² for the right handle. These figures look really good when compared next to the same model loop handle brush cutter. At this stage I am not sure, at what speed these reading were taken or an average over the total speed range.

ECHO SRM420TESU - Engine cooling 2 (600x562)

The four point anti-vibration system on this brush cutter, is pretty much a copy of that used in the commercial Husqvarna and Stihl brush cutters. There are two vertically aligned rubber isolators at both the engine and handle bar end to absorb engine and gear head vibration.

ECHO SRM420TESU - Engine cooling 3 (600x320) ECHO SRM420TESU - Engine cooling 5 (600x403)

Below is a close up of the top, engine to handle bar rubber isolation mount.

ECHO SRM420TESU - Engine cooling 8 (600x413)


Gear Head

The gear head is the second of a new breed of high torque hear heads, with this one having a gear ratio of 2:1, meaning that the engine turns over at twice the speed of the cutting blade.

ECHO SRM420TESU - High Torque Gear Head 1 (600x390)

The quality of casting and finish is again, as you would expect from the Japanese, of a very high standard. I really like the; solid four bolt mount for the guard, the vertical locking pin system and a spring retainer to hold the locking pin in place when undoing the retaining locknut and finally the idea of an exit drain screw to allow old dirty grease to exit as you pump in new grease to the gear head.

The manual recommends using a good quality Lithium grease, but does not say how to get the grease into the gear head.

ECHO SRM420TESU - High Torque Gear Head 2 (600x453)

What I really like about this brush cutter and another one of the reasons for buying this machine was the new High Torque 2:1 gear ratio. In the image below, you can see that the cutting head is rotating much slower, which means it also has more power behind it.

Echo---High-Torque-Gear-Head

Most brush cutters have a ratio, ranging from 1.1:1 to 1.4:1, this giving the most optimum tip slashing speed for a nylon line as nylon lines do not cut, but rely on shear speed to smash their way through whatever you are clearing at that moment. Cutting metal blades do not need such a high tip cutting speed, they actually cut better with a slower tip speed with more power behind it. Very high tip speeds only cause increase wear of teeth, caused by fine dust sitting on the plants, sand blasting away the sharp cutting edge.


Cutting Options & Guards

In Australia this brush cutter comes with a nylon head and one metal blade. It also comes with two quick change slide and lock guards to suit each type of cutting head, which is a feature you will really like if you frequently swap between a nylon line and metal blade.

The bump feed head is a much larger diameter than that normally found on other brush cutters. This to go with the extra power the engine and gear head from this brush cutter can feed to it and come with a full spool of heavy duty square nylon line installed.

ECHO SRM420TESU - High Torque Nylon Head Guard 1 (600x451)

Below is the supplied 8 tooth metal blade and the matching guard attached to suit metal blades.

ECHO SRM420TESU - High Torque Metal Blade Guard (600x442)

Bottom view of the large bump feed head and how the guard slide on and lock in place.

ECHO SRM420TESU - High Torque Nylon Head Guard 2 (600x324)


Harness

Review to come.


Tools

To come


Manuel

The manual is one thick A4 document that comes in four language, English, German, Italian and Spanish. The English version is written in perfect English and spelling (not that I can talk) and is laid out in easy to understand text with lots of sketches. There are all the usual warnings and safety instruction to comply with western safety standards. There is also clearly detailed HOW TO instructions on the correct use, maintenance and proper care for this brush cutter.


Warranty

In Australia, this brush cutter comes with a 5 year domestic warranty and a 2 year commercial warranty. 

What is not mentioned anywhere in the purchase documents or in the manual is that, the warranty registration form must be completed on the Allpower Industries website at www.allpower.com.au within 28 days of purchase or the five (5) year limited warranty will be defaulted to a two (2) year limited warranty. If you really want that 5 year warranty, make sure the store fills it out for you before you walk out the door with it. Also, the exclusions are quite extensive, so if you are considering purchasing an Echo brush cutter in Australia or New Zealand, you should read Allpower’s Warranty Page very carefully before going ahead with purchase. 


Price

The recommended retail price in Australia is AU$999.00 which is a good prices compared to a similar Husqvarna brush cutter at AU$1599.00 and the Stihl brush cutter at AU$1649.00 that are of similar size and have similar anti-vibration handles.

One thing I do like about Allpower’s selling policy, is that even if you buy your brush cutter on line, it will be sent to the nearest Echo Dealer to you for you to pick up. With this system, at least some of the dealers in the smaller towns that are struggling to survive in the new online world, will get some commission. 


What is not so great about this brush cutter

Gear Head Binding Up;

This for me is one of the most frustrating things about brush cutters, and that is, long stringy grass, (Kikuyu grass as shown below) vines of all types wrapping around the gear head and stalling the brush cutter.

For most line trimmers in suburbia, this in normally never an issue, but this is a serious commercial brush cutter that should be able to handle everything thrown at it. So now having the power, I thought I would through more power at it, Nope, all it did was rip the very heavy nylon line from the feeder head. Click here to find out why weed wacker lines break at the bump feed head. So now you not only have to stop to untangle the long grass, as you would with any brush cutter, you have to also pull the head apart to feed out more line. After this happening twice , I went back to my BrushDestructor Blade.

Echo SRM420TESU - Poor design of gear head causing grass to tangle arounf gear head (600x179)Click Photo to Link to Page

In this case, we have a completely new design high torque gear head, but no thought was given to address this problem. I used to think that a more powerful brush cutter would solve this, unfortunately more power does not solve the problem, as you can see in this video below.


Gear Head Gets Very Hot

I noticed that when I was untangling some long wet grass that had wrapped around the gear head, that it was giving off steam. For some silly reason I put my hand on the gear head to feel how hot it was, but if I had to pull it away very quickly I would have burnt my hand. I do not have a temperature gauge to measure the actual temperature of the gear head, but it gets so hot after 5 minutes of use, it will vaporise water away in a few seconds as shown below. This temperature means that some of the power that should go to driving the blade is being wasted as heat and could explain why the fuel consumption is so high.

Temperature-of-Echo-High-Torque-Gear-Head

I checked the temperature of the gear head on three other brush cutters after a similar time and they where barely warm to the touch. Not sure at this point whether this is a one off fault or a design flaw with this gear head, but looking at a section of the gear head I suspect that it is the three small bearing stacked in a row as this feels to be the hottest part of the gear head. The reason why they put three bearings in a row is to give more stability to the small drive gear, but they could have achieved the same result with a spacer between two bearings saving cost and friction from the extra bearing. 

Echo High Torque Gear Head.Still001 (600x335)

I will go back to the manufacturers on this one and add their feedback here when I get a reply.


Poor Design of Metal Blade Guard

Echo SRM420TESU - What I don't like about it 1 (600x256)

As can be seen in the photos below, the slide on guard for metal blades, does in fact not shield you from the supplied metal blade.

Echo SRM420TESU - What I don't like about it 2 (600x270)

Below is with the BrushDestructor Blades fitted, as you can see it offers no protection at all.

Echo SRM420TESU - What I don't like about it 3 (600x262)

Here you can see how I have extended the guard with a 2.5mm thick aluminium sheet to protect the operators feet from flying debris.

Extended Guard on Echo SRM420TESU Brush Cutter 1 (600x319)Extended Guard on Echo SRM420TESU Brush Cutter 2 (600x242)

If you are thinking of purchasing this brush cutter, make sure that you get them to install the Echo approved extension so as not to void any future warranty claims. If you already own an Echo brush cutter with one of these guards, go back to your Echo Dealer and ask them to install the approved guard extension at no cost.


Engine connected directly to shaft

On this model the engine does not connect to the shaft via a rubber vibration isolator, but instead it is connected directly to the shaft.

Echo SRM420TESU - What I don't like about it 4 (600x319)

I guess the theory here is that they do not need a rubber isolator here because they have a large handle bar isolator system. The problem is, that by not isolation the engine from the shaft, vibration from the engine travels straight down the shaft.  So now we have two sources of vibration, the engine at one end of the shaft and the gear head at the other end and a shaft that vibrates like a guitar string.

If you hold this brush cutter up and run it at any constant revs, it is possible to see and hear the harmonics of all the different vibration frequencies running up and down the shaft. In the video below, you can clearly see this 28mm diameter high strength aluminium vibrating like a guitar string.

The Manuel for this brush cutter states that the vibration measurements comply with (ISO22867), I did look at buying this ISO code to find out exactly how the measurement are supposed to be compiled, but at $250  I thought I would put the money towards a vibration meter instead. Click here to read more about vibration and Hand Arm Vibration Syndrome.

The manual states the reading for this brush cutters handles is 2.8m/s² for the left handle and 2.3m/s² for the right handle. These figures looks really good compared to the same model loop handle brush cutter with a figure of 3.5m/s² for the front handle and 5.1m/s² for the back handle. However in practice, this does not seem to be the case and to my already damaged hands, it feel much worse than the 35cc Honda bush cutter I use the most.

At this point in time, I am not sure if the reading is the average for the complete rev range or at just full throttle. I do not have a vibration meter to actually measure this yet, but I have ordered one.


Noise Level

This brush cutter is aimed more at the commercial operator, who uses a brush cutter for many hours in a row, but compared to the Honda brush cutter that I am used to, the noise from this machine is horrendous. I am sure that with the technology we have now, they must be able to design a muffler that is much quieter without adding too much weight or loss of power.

Echo SRM420TESU - What I don't like about it 5 (600x194)

After having become use to the noise level from the Honda engine, which I still think is louder than it could be, I personally could not put up with this level of noise for any length of time.


Hitch Point

On this particular brush cutter, the hitch point is fixed in relation to the engine and handles. However it does give seven points on which to hitch up to, to balance this brush cutter, unfortunately they are all in the wrong point to correctly balance this machine.

One of the best ways to reduce vibration to the hand, is to have a looser grip on the handles and to push forward & down on the handles with your palm instead of pulling back & up with your fingers. Unfortunately, even using the most forward hitch point, this brush cutter is far from being balanced.

Echo SRM420TESU - Front hitch point still does not balance this brush cutter (600x314)

With the supplied nylon feeder head and guard fitted, it requires 0.6kg of water to balance this brush cutter and that is with a full tank of petrol. To allow to balance with half a tank of petrol, you will have to add another 0.4 kg to the counter balance, that means a 1kg countre balance weight just to balance this brush cutter. There is no way to adjust the hitch point on this model, so the only option is to bolt a metal plate to the back of the brush cutter to add weight. Obviously the designers of this brush cutter, have never used this machine for any length of time, otherwise they would not have made this stuff up.

Echo SRM420TESU - Nylon Head Requires 0.6kg to balance (600x469)

With the supplied metal blades and modified guard, it takes 0.7kg of water to balance it and with a BrushDestructor blade fitter it takes 1.5kg of water. Add another 0.4kg to allow for half a tank of fuel and that means a 1.9kg counter balance weight fitted to the back to balance this brush cutter.

Echo SRM420TESU - BrushDestructor Blade Requires 1.5kg to balance (600x447)

Below is a copy of a small portion of the manual, about correctly balancing the brush cutter before using. Obviously the writer of the manual new about the importance to balancing the brush cutter, it is a shame that the design engineer of this brush cutter didn’t read the manual.

Echo Brush Cutter Manual - Brush cutter balance - (600x338)

If you can read the writing below the WARNING in the picture above, it says do not use this machine if you are tall enough that you feet can reach the cutting attachment. I am tall enough to fall into this category, its a shame there was no mention of this in the sales literature, (what sales literature). Maybe it was easier to add this statement to the manual than modify the metal blade guard mould to properly protect your foot from the blade?

So if I abide by the warning, what do I do with it now. They wont take it back, but are they legally liable for selling me a machine, that by their own manual, states I should not use.

Below are the steel counter balance weights I made, just to balance the brush cutter for the standard nylon head.

Counter Balance weight for Echo SRM420TESU Brush Cutter

I have made two modifications to this brush cutter now, so I am sure that by adding the guard extension and counter balance weights, I will have thrown any warranty out the window. So if you are thinking of getting this brush cutter, insist that your local dealer fit an Echo approved counter balance weight, not a home made one like that shown fitted here. If you already own one of these machines, take it back to the Echo dealer for them to fit an an approved counter balance weight.

Counter Balance weight for Echo SRM420TESU Brush Cutter 2 (600x398)

I was just thinking that it would be nice if some of this extra weight needed to balance this machine, was put into a larger better designed muffler that worked instead of having to put up with the horrendous engine noise from this engine.

I have just noticed that Echo have come up with a novel way I would never have thought of, to improve the balance of this brush cutter. Now this is what I call thinking with your male appendage, (lets throw some more noise and power at it), so now it comes with what I think is a 52cc engine. Perhaps you should read this page of theirs, maybe you can find the size of the engine, I must be missing something. Echo SRM520ESU Brush Cutter 

These brush cutters now comes with a SUPER ANTI-VIBRATION SYSTEM, but wait there is more, it also now comes with a BICYCLE-STYLE HANDLE FOR OUTSTANDING CONTROLIt is a shame they couldn’t put some more useful information and technical details on this page, instead of being more creative with words. It just goes to show how gullible people are to some fancy words, I mean I went brought one on this amount of information and I yet I would not have thought of myself as being gullible.


Poor Control of Cutting Head

The design of the handle bar isolation system results in a lot of play and lack of control of the cutting head. This makes it very difficult to prevent hitting hidden objects in the grass, because if you try to quickly reverse direction the cutting head will travels for another 100mm or so before it reverse direction. The result is a very vague feeling and difficult to control cutting head.

Swinging-Shaft

This may not be too much of a problem with the nylon head, but any metal blade that relies on staying sharp to cut efficiently, than this is a big problem. 


So there you have it, all the good and not so good points for this brush cutter. If you are interested in purchasing one of these machines, start with what you have learnt here, then ask the supplier any further questions that you need to make an informed buying decision. If you cannot get the answers you want from your local Echo Dealer, you can always email Andrew Jacobson at Allpower Australia . As of July 2018 Allpower have gone bust and Briggs and Stratton are now the importers for Echo and Shindaiwa brush cutters. Hopefully Andrew did not move across to Briggs and Stratton. Or you can email Kanako Morishita at Yamabiko Corporation k_morishitaxx@yamabike-corp.co.jp I am sure they would love to answer any questions you might have, NOT

GOOD LUCK AND HAPPY BRUSH CUTTING


On the 09/04/15 I sent an email to both the above gentlemen with the questions raised above and a link to this review for their comment and feedback and to date I have not received an answer. If at some stage I do get a reply from them, I will place it here for you to see, but I an not holding my breath. As of August 2018 I have not received any reply and do not expect one.

If I was in charge of this section at Echo, I would be contacting the person who wrote such a review and asking more questions as to why that person made such claims as were made above and if I found them to be true. I would implement changes to resolve these issues and make future products better. As of July 2018, Yamabiko Corporation, is still selling this Echo machine, to unsuspecting customers that have not read this review. To me, this does not say much for the company.

If you would like to leave a comment below, please limit it to this model Echo 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.

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3 thoughts on “4.3.7.1 – Review of Echo SRM420TESU 41cc Bicycle Handle Brush Cutter”

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