Staton does a side by side comparison, "Which engine is better? Robin - Subaru EH035 or Honda GX35?", and he comes down if favor of the R/S.
He deals with both, and I'm GUESSING the warranty is just as important as the cylinder linings in his mind.
http://www.staton-inc.com/Details.asp?ProductID=3234
All Robin Engines Have One Thing
in Common— Quality!
All models offer heavy-duty features including aluminum alloy blocks with Cast Iron Cylinder Liner, electronic ignition with automatic timing adjustment, dual ball bearing supported crankshaft, automatic decompression system, and splash type lubrication. Optional features available on selected models
Cast Iron always seemed better than Aluminum sleeved, in my mind, its why I chose it for my personal recumbent ride.
I have only used 2 Honda 35 engines, on the 2007 Worksman PAV builds (in the Trike section), but now that I've installed 10-15 of the R/S, I can tell the difference. Once you prime the pump on the R/S, it seems you never have to push the bubble again.
Even Staton's descriptions denote a difference, more horsepower:
Subaru EHO35 33.5 cc 1.60 HP Four Cycle Engine
http://www.staton-inc.com/Details.asp?ProductID=3086
Honda GX35 35.8 cc 1.30 hp Four Cycle Engine.
http://www.staton-inc.com/Details.asp?ProductID=2822
As to the warranty, Honda builds its own power equipment (mowers, generators, etc ) using their engines, which have a full warranty.
Honda also sells engines on the secondary market, which when I installed those 2007 Worksman builds, and read (2 years ago)
it specifically said they don't warranty any uses not of their own making. If a customer bought a Honda Water Pump, warranty. If a customer bought an engine, then designed and built his own pump,
no warranty.
In other words, if the Honda unit had a defect, the customer was on his own because the build was not done by an official dealer.
That may have changed, I don't know. They may offer a full warranty in Australia, again, I don't know, and I also don't know why Robin Subaru isn't marketing identically over in Oz.
What I do know is
Robin Subaru and Tanaka both seem to be catering directly to our unique MB business. When I sell a Robin/Subaru or a Tanaka, I know GEBE will stand behind it and the manufacturers too.
So, my point is, this MB member has asked in separate threads what the "best/quietest" engine is, and based on my experiences, if a Honda was available immediately, and a Robin Subaru was on 1 month back order,
I'd wait the month.