I'm sorry I'm not sure I understand you, are you comparing two stroke engine to four stroke engine??

If so I like the two stroke for lots of reasons.
I like the smell and sound, I like to tinker on them and use my mechanical senses, I like the power from them better, I like the light weight, I like that they get a steady supply of FRESH oil, I like the fewer moving parts in the engine to wear out or break, I like the concept, I like the variety.

I'm sure there are more but I'm a crappy typer so there are a few of my reasons.

Neal

yungman I know you're just trying to learn and understand but you kinda repeat question just worded different.

Bottom line if user does EVERYTHING by the book, fuel mix versions of mini 4 strokes has the advantage over using a oil sump. Reason, it nevers has anything but clean oil protecting the innards. The raw fuel/oil sump types really aren't a disadvantage if the oil is changed on schedule but the reality is few people do it.

Doing what you should on any of the diaphragm carb engines includes having the carb rebuilt at least once every couple of years to keep it working right. Echo even goes further in scheduling carb rebuilds every year for home users. Todays fuel is so hard on diaphragms that to keep them working right means more maintenance.

Mix fuel does not go bad faster, in fact if using a quality 2 stroke oil the fuel last longer. Quality 2 stroke oil does have some stabolizer in it. In my opinion its not enough to stand on its own without adding your own dose of stabolizer for fuel kept over 30 days but they are better then nothing.

The single big advantage for an oil sump mini 4 stroke version is if all your other equipment is 4 stroke. Unless you have a old 2 stroke mower or other 2 stroke hand helds like hedge trimmers or chain saws, it is inconvenient to have a second fill can with mix.

Hi Nevada Walrus
How are you? Thanks for you advice.

I know I have been beat around the same type of questions.One thing I learn, people have different opinion, you ask 100 people, you get a lot of answers, but if you listen to their logic and think about them, you learn more. Even you ask the same people, they might say something a little different and you can learn too. That is the reason I ask a lot. This is kind of like my hobby and I am trying to catch up.
Thanks

Yes, I would say the 4-cycle with separate oil sump is the most forgiving. However, if you include vehicle, marine and industrial engines, you can't ignore the venerable Detroit Diesel 2-cycle truck/bus boat engine with cam/valves and oil sump. These engines require a supercharger (to blow the fuel/air in and the exhaust out), but do they ever work! Many locomotive Diesels are also 2-cycle. Constant speed of 900 RPM!

Hi Saxman1
That is how I felt, but apparently, most people do not agree. I put this post in another forum and I got a lot of reply. I have no strong opinion. I just want to listen and learn.
Thanks

Another advantage of any engine using a gas/oil mix (regardless of combustion cycle) is that if the engine is getting gas (i.e., if it is running) then it is getting oil. It is possible to tilt a sumped engine too far and starve the oil pump pickup or splash device, resulting in damaged friction surfaces. It's also possible to tilt the mower too far toward the cylinder head and/or carb and flood the chamber and carb with oil. That makes a mess and a very smokey start at best, and I guess it can hydrolock the engine at worst. Of course, as with any engine, if you operate and maintain the engine according to directions these problems don't happen.

And I love trumping anyone's citation of diesel engines by citing the Wartsila-Sulzer RTA96-C turbocharged two-stroke diesel engine. It's the largest, most powerful, and most efficient piston engine around. It displaces 1,556,002 cubic inches (25,480 liters) for the fourteen cylinder version; length of 89 feet; height of 44 feet. It makes 108,920hp and 5,608,312lb/ft at 102rpm. Can you imagine the sound of this thing running?

Here is a link that might be useful: Wartsila-Sulzer RTA96-C

Wow! I had seen that before - what an engine!
Sure, 2-cycles have advantages and so do 4-cycles. I like and use them both, in mowers and other equipment. But, I understand yungman's thinking on this, and I have thought it too. A 4-cycle mower is basically easier to use and requires less elaborate preparation to run. Fuel-mixing and air filter cleaning are probably the major pains on the 2-cycle, with the looming possibility of inadvertently using straight gas being the chief reason it's less 'forgiving' than a 4-cycle. If you put 2-cycle mix in a 4-cycle, you may not notice anything. If you do the reverse, the 2-cycle will be ruined.

Wonder what it costs to overhaul one of those babys???(the Wartsila-Sulzer that is) Wow.

When I post this, my thinking is that you use according to their limits, you don't till the car/ lawnmower to 45 degrees to operate, you change oil.
1)If the carb gone out of wack( and it will) and get too lean, it will be more forgiving. For 2 cycle, not only you run hot, you starve for oil and die.
2) If getting too rich, only carbon from gas, not from gas and oil in mixed oil case. Carbon break off and damage cylinder has been known.

For smaller trimmer 4 cycle, they all design to be able to work at any position.

These are my thought, they can be wrong, what do I know!!

I thought I over-analyzed things. Any quality machine treated correctly will last a homeowner for years & years. Pick one and open up your wallet. Pick the one that feels good in your hands.

Yungman, In 4-cycle engines if the carb is too lean for a long time you can burn the valves. In 4 cycle engines the oil does not have to be mixed but is has to be checked. If someone can make a mistake mixing 2-cycle oil that same person can forget to check 4-cycle oil and eventually run it dry. With synthetic oils 2-cycle engines can endure overly rich mixtures without carbon forming or plug fouling. Also I cannot say I have seen many engine failures related to lean mixtures with outdoor power equipment. Motorcycles and other high performance 2-cycles can melt down in a heartbeat from lean mixtures but most string trimmers and mowers are not that high performance and do not suffer the same types of failures for the most part.

You sure about synthetic oil, you can put more oil and it won't foul plugs and built carbon?

I am not considering people don't add oil or not changing oil,( it is obvious of the color if you forget to put oil in. I can never understand how people can forget... blind, out to lunch, doped up!!). Nothing is fool prove. I am refering to the unforseeable things like partially blocked carb that don't provide enough gas. This is conditions that can occur and not easily detectable until is too late for the 2 cycle.

If the carb is that "blocked" or gummed up, most engines won't even start or run long enough to build up enough heat from friction to do any damage whether it be 2 or 4 cycle.

yungman, Your statement about a lean condition from a partially blocked carb causing problems is true and quite common. Usually a lean condition on a governed engine like a mower is apparent from loss of power. Slightly lean conditions may not be so apparent and can cause problems.Your assumption that it is detrimental only to 2 cycle engines is not quite true. Both 2 and 4 cycle engines are affected by lean conditions. An lean carb causes the mixture to burn much hotter just like a cutting torch burns hotter when the oxygen is increased. This heat can damage either 2 or 4 cycle engines in different ways. 2 cycle engines that are too lean can burn a hole in the piston or piston siezure can occur among other things. Four cycle engines that are too lean can burn exhaust valves and seats and possibly overheat and cause the rings to lose their tension. Your statement that people may be "out to lunch" or "doped up" is sad but true. Most of the failures that I see are caused by user neglect or abuse. Other failures that are common are what I call planned failures like ignition coils, soft metal cutting blades that wear too quickly, etc. etc. Manufacturers design acceptable failure rates into certain parts that nobody else makes. CD ignition coils are a good example. They are propritary parts that usually fail a few years out of warranty and cost about triple the money that they should. What manufacturer wouldn't want to sell a $50 ignition coil for every mower they have sold at some point in the future? Sell a million mowers and sell that many coils. What a windfall!! Motorcycle manufacturers are notorious for doing that with all kinds of cd packs, voltage regulators, pulser coils, switches, and relays. Sorry I got a little off track....

Hi Rdaystorm
Thanks for your detail reply. I agree about the plan failure. The air conditioning and wipper fail after the warrenty ended....BUT...I am one up on them, I bought the extended warrenty!!!! They still have to cover all that. I always buy extended warrenty on cars, TV, and VCRs. I tell you, I got every single penny back. My Honda got a new tranny at 75,000miles free. Start out a recall that I did not get notice that was what cause the transmission to fail. They were reluctant to do fix it at first, but I bet whan thay find out I have the extended warrenty, they gave up and change the transmission....Free!!! You don't even know how many times my VCRs went in for surface. I tape all my shows and watch them later. The VCRs were working overtime. My giant screen fail 4 months before the extended warrenty expired, free again!!

They make stuff so cheap now a days, extended warrenty is just part of the cost!

Thanks

Hi Everybody
After asking all the questions repeatly by different wording again and again. I Bought my trimmer. It is a Honda HHt31SUNBA, the one with bike handle 31cc. discontinue model.

I can't get over the timing belt of the GX35 and I am not comfortable with all the oil mixing, carbon buildup on 2 cycles. This Honda is the old push rod OHV engine, no timing belt, no mix oil, very quiet. Heavy like anything but don't bother me at all because it is a bike handle and have shoulder straps. You should see how quiet it is, when you rev it up, the noise of the string spining is as loud as the motor. This is very important for me living in the "progressive" bay Area of the People's Republic of Kalifornia!!!!

To all of you that think I am beating around and around. Thanks for all the input, believe me, they help for me to make the decision. I read the posting over and over to make sure I did not miss anything so I can make the most informative decision for myself.

Thanks