Zama RB-K89 vs Walbro WYC-9

[sawman]

The Echo SRM-2620 Has a hollow steel drive shaft which makes it lighter. There is a kit available to convert it to a flex shaft.

[KE4AVB]

Just to clear up a few things...Doesn' mean they haven't changed since the release.
From Echo Press Release

Chicago, IL (5/2/2016) The ProXtreme Series 2620 power head is what makes this lineup exceptional. It offers a unique combination of high power and low weight. The newly designed 25.4 cc professional-grade two stroke engine delivers 1.35 horsepower. The weight reduction is achieved primarily by using military-grade magnesium versus aluminum. Better air filtration is provided by using a two-stage air filtration system. An insulator plate and flexible bellow-style fuel transfer system dramatically reduces heat. That system, combined with a remote fuel tank air vent versus an integrated fuel cap vent, prevents clogging and reduces re-start issues. The larger fuel tank allows for extended run time between fill ups.

The SRM-2620 and SRM-2620T trimmers both feature a solid shaft for lighter weight and quick acceleration. The SRM-2620 uses a 1.62:1 gear reduction, while the SRM-2620T features a 2:1 gear reduction. This enables 23% more torque than the SRM-2620 for powering through thick, dense ground cover and optimal performance with a cutting blade. The higher torque range of both models eliminates the need to run wide open throttle to achieve peak torque. This keeps the unit cooler and saves fuel. The units also cut 17” swaths and use the easier- loading Speed-Feed™ 400 head.

The SRM-2620U brushcutter also features a solid shaft. Gear reduction is 1.62:1. The tool-less, adjustable U handle has an integrated throttle lever and can fold parallel for storing and transport. It comes with an additional shield for blade use and shoulder harness. The blade is an optional purchase.

The PE-2620 edger uses a flex cable drive which enables a curved shaft design for better sight lines and more ergonomic tool positioning when in use. The contoured aluminum debris shield with open face reduces clogging. The captive wheel mount hardware enables easy wheel height adjustments with no chance of losing any parts. The 2:1 gear case powers through tough overgrown grass.

As far solid vs flex shafts I have no experience with the Echo solid shafts but I do with the Husqvarna version and the customer is stripping them several times a year. A little rough at 50+usd each time plus shc. I do know the so called solid shafts on the Husqvarna are hollow to allow small amounts of flexing.

[Merkava_4]

KE4AVB

Thanks for posting that press release. I'm wondering why Echo put the 1.62:1 gear head on the on the SRM-2620U brushcutter instead of the high torque 2:1 head.

[bgsengine]

KE4AVB

Thanks for posting that press release. I'm wondering why Echo put the 1.62:1 gear head on the on the SRM-2620U brushcutter instead of the high torque 2:1 head.

You can also get the T (high torque) with U-handle and brushcutter conversion kit

[KE4AVB]

KE4AVB

Thanks for posting that press release. I'm wondering why Echo put the 1.62:1 gear head on the on the SRM-2620U brushcutter instead of the high torque 2:1 head.

Demand and use expected most likely the engineers reasons( my opinion only). Many brushcutters are never used as brushcutters but as trimmers instead. Many of my customers prefer straight shaft trimmers over curve shafts as they are able get under decking and hedges better. Being 6' myself I find that most of the home owners curve shaft models simply don't work for what I trim. Another thing that works for is straight shaft that is longer in length as I don't need stoop over while using them. This is something I had a hard time doing and is why still using very old Homelite trimmer but the Stihls I find works but are hearvier and doesn't help my lower back problems especially trimming out 6 acres.

If I was still primarily doing brush work I would opt for the extra torque for the blade as I would use a fairly aggressive saw blade (The ones with chainsaw cutters) in heavy brush. At one time I did keep two trimmers with one setup with a heavy tri-arc blade just for going fishing as I like to fish way off the beaten path that were the big ones are anyway. Only one problem with that as others sometime found my trails. They usually left a mess but while cleaning their once a C note along a very expensive hunting knife was found. Well I got paid for cleaning up the trash that day.

[sawman]

When the SRM-2620 was first introduced it had the hollow steel drive shaft. In December of 2016 ECHO made a running change to the flex cable. To identify units built with the flex cable the serial numbers will have a prefix of; T942, T943 and T944 or a date on the emission decal of Dec 2016 or later. Also another visual identifier out of box the trimmer heads will have a Black colored trimmer line. The changes were implemented to alleviate some vibration concerns some users were finding at certain RPM’s. So you want to check the serial number to tell whether you are getting a hollow steel drive shaft or flex shaft.