Outdoor Power Equipment (Lawn Mowers, Snow Blowers, Chain Saws and more) Discussions

I apologize if this is an elementary question but I am a new homeowner and do not have alot of knowledge on engines in general.

I have a 1/4 acre lot and plan to do my own lawn maintenance. I've already purchased my mower and am now looking at getting a trimmer.

I've noticied the big difference in gas-powered trimmers seems to be 2-cycle or a 4-cycle engine but I'm not clear what the pros and cons are of each. Also in some of my research I see that some units take straight gas whereas others require a mixture. I'm just completely confused at this point at what to even start looking for. I dont have a large lot that requires a tremendous amount of trimming but I want to purchase a unit that will be durable and most fit my needs. Maybe my needs would be better suited with an electric model?

Any explanations and advice would be greatly appreciated.

One of the biggest advantages on the small 2 stroke engines is they do not have valves (valves on small air cooled engines wear fast or burn out much more readily )  ( to be specificn no mechanical valves)  They have ports, same as saying slide valves etc. No need to go into the actual operation.  The reason it is an advantage is small engines in the ope equip are high revving engines, the two cycle is better suited for high revs as it fires every time the piston comes to top dead center.  (the piston fires every rotation of the engine, not every other rotation as in a 4 cycle) that is important in a small engine doing this type job as for example a string trimmer.  These engines create a lot of heat running fast so that is why a 4 cycle engiine with mechanical valves would be detramental,  because with high heat the first thing to go is the valves.  Less parts on a two cycle, easier to repair,  you can call them self lubed if you want to, because whatever angle you put them at,  as long as it will run , most carbs won't run upside down, some do however,  great for airplanes  just kidding.whatever angle you put them at as long as they are running and you have oil in your fuel, then they assuridly are oiling themselves,  it is a fool-proof system, why, because if they are not oiling themselves they will not run.  The traditional system brings the oil and fuel mixture thru the crankcase first before it enters the combustion chamber.  there are some slightly modern enhanced versions who bring it thru the crankcase and a small inlet into the combustion chamber also.  but the engine will not run on that alone. 

 Not having valves that will burn out when run hot is an advantage.. Sure some one  will prob say they now heat treat the mechanical valves, which helps but they still burn Combustion heat on both sides of an exhaust valve which starts them splitting at the thin tips, it is hard to protect against that in these small engines.  Which is the reason that for generations they were nothing but 2 cycle.  And of course 2 cycle's have never burned out a valve.  LOL  it's true

If you want to chance adjusting or replacing valves in the future, then buy the 4 cycle.  they are nice engines and up to modern day tasks.  Just more potential kinks in their armor.. not to mention they can be heavier , more expensive, and you have to chg oil. they are a bit more quiet and have less vibration. But for the amount of time you use them,  even on a complicated property, the 2 cycle that will not burn valves is much better on your pocketbook  .  You spent 200 to 400 on a string trimmer, you sholdy consider how often you want to spend that, or put up with a little noise for awhile etc. (old saying "every thrill has it's chill"

Ben07

Ben07 wrote:
Ben07,
I don't disagree with everything you wrote in the above quote, I just take at least some exception to most of it.

Seezar,
In general, in my opinion, small trimmer and chain saw engines have changed so much in the last two years due to emissions, unless you are a pro user or fixer it is very hard to keep up. If you want to go inexpensive, go to a box, find one you like, check the return policy (make sure it is open ended for date), keep box and reciepts (everything that keeps the return policy in effect) and use it to your hearts content. Don't like it for any reason, take it back.

Once you find yourself spending $100 or so to get one you like, Bite the bullet  and maybe check into some good machines at a dealer. Echo, Redmax, Stihl, lots of other brands to consider, some well know like Honda, some not, like Shindaiwa.

Unless you have a preference, like not wanting to mix oil in the gas, I don't think I would worry about the two stroke-four stroke thing too much.

By the way, Welcome. And I am not a pro anything, please take my opinions for what they are worth.

robmints wrote:

Sorry Rob  but when I read his question I thought he specifically wanted to know what the pro's and cons were of a 2 cycle engine vs a 4 cycle  engine, Actually it is the title. I think every response has been on their differences, He even stated that he has looked at them and has come to the main differences are wether they are 2 cycle or 4 cycle, and that is specifically what he seemed to want to understand.   Apparently you only have a problem with my post ???   Actually most of mine. At least that is what you said, specifically what, I am not sure.    Maybe somethings wrong and I should erase the post.  I did give credit to both types, however far little to the four cycle in this small size market.  Now If I was going to give an opinion as you did, for which I might add he asked for explanations and opinions,  I gave him an explanation, and you gave him an opinion,  and you stated your opinion was based on my explanation.  Saying don't worry about the explanation you asked for, just go out and buy, then keep exchanging etc.    So I will  first give you my opinion on small 4 cycle engines of this size for ope use.  They are going to have to go a long and expensive way on 4 cycle tecxhnology in small engines like for string trimmers, to even come close to how the two cycle can handle it today. It may be able to be done some day, but the the consumer will pay a lot more.  .  The 4 cycle in this size is a mere toy compared to it's counterpart.  Also where we disagree is to have someone ask for an explanation, and tell them to go to the store and poke and hope till they find one  by trial and error and countless hours at the service desk.  when that is why they may have asked the question in the first place so as to not to have to do that, as much.  And this type practice makes the cost of goods and services higher for everyone in the long run.   Apparently they wanted to gain some knowledge before going out shopping again.

keep this in mind and let me quote you "I don't disagree with everything you wrote in the above quote, I just take at least some exception to most of it."     and at least I had the courtesy to explain why

Ben07

My professional opinion..............( I run one about 5 hours a day in the summer)  2 stroke all the way.  Nothing but Shindaiwa for me.  Smooth, powerful, built to last, light weight.

4 stroke.............BOAT ANCHOR HEAVY, ROUGH RUNNING, LOW POWER, VIBRATION (did I already say that ) BUT..........Very smooth idle...........if that is good for anything.

I tried out a Honda, Shindaiwa and Stihl...................didn't like any of them.

The Honda dealer was begging me to try one out.  I used it for about 20 min. and was NOT  impressed.  The others were tried for less time, but my review stands.

But hey....................that's just me.

Ken

PS-------I ONLY run Opti-2 for mix.  At the mix ratio I seriously doubt I am polluting any more than a 4 stoke engine.

Oh yeah............................WELCOME to the club, Seezar!  

Ken

Thanks everyone for the welcomes and the helpful info!

After reading all these replies I can see I'm not yet any closer to picking out the exact trimmer for me, but I've gained some knowledge.  That was my intent in the original post was to understand the difference in the 2 types of engines, it just happened that the reason I wanted to understand was I'm in the market to get a trimmer.

I think its going to come down to just going out and looking at a few different models, and as what was mentioned, try some out and use the return policy if needed. The last time I used a trimmer was about 15-20 years ago so I'm sure things have changed quite a bit since then.

Thanks again everyone, this is a great forum and I'm glad I've stumbled upon it.

Seezar  by the way it might be a worthwhile idea to start out with an inexpensive electric one. Then you can get the feel for what you prefer.  They serve as an excellent back-up, as in storage they don't have some of the problems you will have as with storing a gasoline one.  (carb gumming from some gas left in it, the magnet surfaces getting rusted there-by not enabling the sensor to pick up the point to fire the engine etc etc.)   I gave an old electric one to a new neighbor a couple years ago, it was about 25 yrs old, wasn't used in like 20 years, I stored in the worst way, a plastic bag.  Ran like it was new and he has been using it now for two years.

Ben07

I'm with you Ken, I'm a 2 stroke man all the way when it comes to trimmers and blowers, for the same reasons you mentioned. I do like 4 stroke thumpers though, in bikes!

Ben07,
Sorry I was so abrupt. No excuse, but I was in a hurry.

I am not an expert. I think I have owned over a thousand horsepower of two stroke machines in the last 20 years or so. I really like two strokes as a design.
Maybe I haven't been looking as close as I should have been, but in that 20 years I have only seen one two stroke engine that did not have some sort of valve, mostly reed valves.
I think the two stroke we used to think of, for the new purchaser, is gone. Most of the small, newer design two strokes look to have significant design changes to meet emissions standards. Many seem to have what we might consider a four stroke style valve, with a stem and seat. Some look like they differ on how they are actuated, but they do what they do on four stroke. Some engines seem to try to get away with what we used to call "loop charging" where the exhaust is reported to or held in the cylinder. Some seem to use a little "CVCC" thing that opens wth vacuum or pressure and closes with a spring. Others seem to use a cam and spring just like four stroke. But, for the most part, our beloved two stroke is dead. Onward and upward in the fantasy land of the EPA.

One thing with gas trimmers more than one person has indicated that they did not like was something called a split crank. I think they say you can tell by the recoil start being between the engine and the shaft. I have no idea what they are talking about. Hopefully someone that does will have some input.

Like you posted, Ben, electric might be something seezar might really want to consider.  Again, sorry, did not mean to seem like a jerk. Wasn't intentional.

hey guys...

ive been reading this since it started,and have a few things to comment on.

first is 4 strokes...in my professional opinion and im the pro here...they are all crap even the honda or maybe especially the honda cause they know better.

and the shindiawa,which is normally top quality equipment well we sell them and there is 5 pages of service bullitens that have to be done to them...thats crap to me.

as far as power the 2 stroke rules and the 4 stroke isnt going there any yime soon.

now that being said there are some real crappy 2 stroke trimmers out there.best way to tell if its any good is to take a look at where the starter recoil is.

if the starter handle is on the shaft or boom side then its a low buck special...exactly 1/2 crank in there,and also usually made of pressed and pinned sheetmetal.the crank is only supported on one side of the connecting rod.

if the starter is on the top side  away from the shaft then it is a full crank and usually has a real crankshaft 

and it is supported on bothsides of the connecting rod . 

dosent matter what kind of brand it is the one with the good crank is always better than the one without.

i have never seen a poor machine that had the full crank ,they all have good quality product and some of them have not so good product as well.

read what folks have to say here and be advised.

as far as the 2 strokes being non emission friendly,well just do your part use a good quality synthetic mix oil and dont let it go stale.

later chris