Honda & Robin Mini 4 Cycle Engines

[cryptokid]

although i am generally impressed with honda and subaru products, i am not a fan of small 4 stroke engines like this. the 2cycle is perfectly suited to small handheld tools better than a 4stroke will ever be. although the design and quality of these 2 engines is impressive, they still weigh alot more than a comparible power 2 cycle, and on small handheld tools like this, weight is critical.
somthing like a poulan 1hp 2 cycle engine weighs about half what these 4strokes weigh.

 

[Blue99]

Two relatively new engine designs used in string trimmers applications meeting the EPA 2005 restrictions.

Is this a Honda design licensed to Robin ? The engines look identical, yet exterior dimensions are slightly different as are the bore x stroke.

Honda GX25 Mini 4 Cycle Engine

Robin EOH25 Micro 4 Cycle Engine

Also, the oil capacity is only 2.7 oz., virtually the same quantity as the small 50:1 mix bottles for 2 cycles. I’m really amazed that this small amount can provide adequate lubrication. Wonder what the typical consumption is?

 

[NThomas]

Robin makes a OHC small engine as well as Honda. I am not sure if these are the same on the trimmers or not. They look the same but would guess that they would have to say its a Honda engine, Maryama does!!

And most the Poulan engines are junk!! Yes, the 2 stroke are lighter weight on some equipment. I have a 32cc Husky trimmer that is only 1lb lighter than the Honda 31cc trimmer. And the 4stroke honda is ALOT quieter

 

[SteveD2]

Here's another interesting engine, 4 cycle that runs on gas/oil mix. Not only that but it's supercharged!

http://www.shindaiwa.com/c4tech/index.html

 

[Blue99]

Zm - That Shiny engine is an interesting design with the pressurized flow thru the intake valve. 10,500 rpm is impressive for a little pushrod engine!

As the Shindaiwa chart indicates, this design has one of the best ratings for EPA emissions.

I'm curious how clean the engine is after 100 hrs of run time, if deposits form around the exhaust valve. It does burn 2 cycle oil, but it sees only 1/2 the combustion cycles that a 2 cycle generates if both engines are running at the same rpm!