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.

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  

Canada

USA



Chris, As you know many of our true two strokes are NLA here. We get more and more stuff like Stihl 4 mix engines. For instance we can't get a FS85 here. If it's not one thing, It's an udder.

I never noticed this before but it's pretty strong selling foo foo dust.


http://www.echo-usa.com/300.asp

300 Hour Certification

INDUSTRY FIRSTS | CATALOGS | MANUALS | FAQs |

With a premium brand like Echo, you expect professional-grade performance. And no engines in the industry perform like Echo. Every engine Echo produces is certified with CARB and EPA to its highest useful life* rating – 300 hours. And that’s the highest performance rating there is. Some manufacturers claim professional-grade performance and yet rate their engines at only 50 hours. Be sure to check the label and you’ll find every Echo product will have a 300 hour or “A” category rating. It’s a fact: Echo delivers the highest level of useful life in every product. * EDP is defined by CARB as “Emissions Durability Period”. EPA uses the term “useful life”, which is defined as “…when engine performance deteriorates to the point where usefulness and/or reliability is impacted to a degree sufficient to necessitate overhaul or replacement…” (U.S. Government, Code of Federal Regulations, Vol. 40, Chapter 1, Sec. 90.105, par. 5, §ii)

Rob thanks for the post,  and I am in a little hurry here, so I could come off wrong.    Now I am not kidding when I said thank you.  But I have a disagreement with you saying modern 2 cycle engines have mechanical valves, and we are talking in the internal combustion area, as my original point is they are prone to burn out there on small ope engines, like string trimmers etc. 

The engine you posted and used as an example is not a two cycle engine. It is a hybrid.   It isn't even close to a 2 cycle. it uses a 4 stroke cycle which needs mechanical valves in the combustion area..

Stihl is one of the new kids on the block with it, so I will post their info admitting it is a 4 stroke.

I have never seen any 2 cycle engine with any internal mechanical valve in the combustion area. (maybe that don't mean there are none so feel free to show me, I'm here to learn)) .  The reed valve is a trap door check valve, sometimes called a flapper valve , flow direction valve, whatever. It is normally between the carburetor and the crankcase of the engine,  In short no where near the internal combustion area.  on some two cycles it is actually incorporated in the carborator.  Certainly wouldn't want any combustion or excessive heat in there. 

The engine you are describing and posting a picture of is called a Hybrid 4 mix.  It is not a 2 cycle engine.  It is a 4 cycle engine with oil mixed in with it's gas, as they are trying to duplicate the lubrication system (and only the lubrication system)  of a reliable 2 cycle, because 2 cycles are able to run upside down and still lube themselves. I will see if I can past  in Stihl's  drawings and explanation of it.  They clearly state it is a 4 cycle engine.  That's why it has valves in the internal combustion area.  What the crazy EPA is  having these guys try  to invent  is a  substitute for the mighty and maintenance free 2 cycle, and they have went as far as throwing oil in the gasoline of a 4 cycle "Otto" engine. I only mentioned the inventor cause I wanted to say he gotta be rollin around in his grave over this. 

     All kidding aside,  I like those young engineers experimenting,  because someday they may come up with something better..It is possible.   But if they do it ain't going to be in fine print at the bottom of an advertisement.  It will be on the front page of Fortune Magazine,  and naturally it will also be so complicated and un-affordable the whole article will be, them telling us how not to worry cause we really won't have to pay for it.  etc etc. 

Here's Stihl's explanation   http://www.popsci.com/popsci/bown/2003/article/0,18881,537079,00.html

Illustration by Garry Marshall

Two-stroke engines (1) have two main benefits: They have a high power-to-weight ratio, and they can be run upside down. Yet these perks come at a price: The two-stroke configuration is valveless, and some of its unburnt fuel leaks out as exhaust. Four-stroke engines (2), though not as powerful, have a valve on the exhaust, so they are cleaner. The crankshaft is lubricated with oil in a pan, however, so they cannot be turned upside down. A two-stroke gets around this by using an oil-gas mixture for both fuel and lubrication. (3) The Stihl 4-Mix Engine takes the best parts of both engines. It uses a four-stroke cycle, so exhaust valves prevent the escape of unburnt fuel, yet its gas-oil mixture lubricates the crankshaft the way a two-stroke does, so the engine can be oriented in any direction. As the crankshaft turns, it sucks lubricating fuel into the crankcase. This keeps the entire crankshaft lubricated even when the engine is upside down.   The real problem I have with their advertisment, is how can they claim they can ever hope to get more power in the same size 4-cycle.  When all they are doing is altering the lubrication system,  (sry but getting rid of a conventional splash system just won't even come close)  My guess would be some of the same horsepower lies we have investigated in other threads, as in using horsepower in and over operating range  etc.  Who knows maybe they are talking at idle speed.  It could be true there.  What good it will do there is beyond me.   Anyhow call it up, some interesting pictures of the different styles of engines. And remember their claim of more power in the same size engine is in fine print at the bottom of the article..Sure ain't the new york times. Ben07

 

snowshoveler wrote:

Hey Chris..........................

Please don't think I'm trying to steal any thunder from you, here.   I do bow to you the professional technican!  I have a landscape maintenance company that has been in business since 1988.  I am definately an end user and not a tech., but with countless hours of use "under my belt", I know what works and what doesn't.  I've tried them all.  I can only extend the knowledge that if something stands up to commercial use, then it will likely be a lifetime purchase to homeowner use.  And, that, is money saved in the long run. 

I think that one of the greatest things about this site is the fact that all the knowledge shared results in wiser spending of our hard earned dollars by "crying once" and buying better quality OPE. 

Ken

I think I really only had two points from the beginning.

Two stroke engines have changed a lot in the last couple of years from what most of us are used to, in order to comply to EPA standards here in the US.

Even old time two stroke engines have valves, called reed valves that can fail and cause the machine to run poorly or not at all. And they do fail from time to time.

robmints wrote:

I remember my dad saying that the reed valves would get weak from "flapping" all the time and would usually be the cause of poorly running machines (usually Lawnboys) that would come into the shop.  I've worn out a few myself from back in the day when we ran Lawnboys exclusively.

Ken

Great in-action working model of a 2 cycle
http://www.oldengineshed.com/twocycthry.html