OutdoorKing Repair Forum Forums Restoring, Customising and Modifying Tech Talk What is the big deal? 2 stroke vs 4 stroke.

Why do some people swear by 4 stroke and others 2 stroke, In my experience(limited), 2 strokes are
fiddly things to work on where 4 strokes are rather simple. Maybe I just found good 4 strokes.
I have been led to believe 2 strokes are worth more to sell. I don't know???

This is my 2-cents...but I thought this was already well known?
There are advantages and disadvantages with both types of engines. I think two strokes are easier to repair imo. There are no valves to speak of and therefore, no camshaft. So, no hassle with valve clearances or bad sealing, which happens when carbon deposits build up around the valve faces and on the seats, or when the valve guides get sloppy. Because they dont have as many moving parts, this makes them cheaper to maintain and repair. This should translate to a longer lifespan.

A huge advantage is, they're more compact and lightweight than their 4-stroke counterparts. Meaning, they are well suited to handheld power equipment like trimmers, hedgers and chainsaws. Furthermore, they don't have a huge sump just to hold oil for lubricating the internals. You don't ever have to worry about a 2-stroke seizing (when you turn it upside down). A 4-stroke will be damaged from oil starvation if you try this.

Disadvantages are, they burn oil, smoke, run/idle rough and are loud. Especially after the piston and rings are well worn. They are also more difficult to tune. Optimal running can require adjusting the fuel to oil ratio depending on weather conditions. Carby needs similar adjustment for hold vs cold conditions.

Victa lost the argument years ago. I remember part of the counter to the invasion of 4 strokes in the 1970's was an advertisement entitled, "It just doesn't make sense" and it then went on to list the advantages of the 2 stroke engine against the 4's. It wasn't enough and people chose 4 strokes that were quieter and seemingly less troublesome.
I am still a fan of the 2 stroke engine and love repairing old Victa's but I do find them harder to sell and I often get,"I don't want to be mixing fuel ..blah..blah". Then I wonder how they work their trimmers.

G'day Seanw..
Personally I think the 2 stroke engine is the easiest engine to work on out of the two hands down ,being so simple in design and putting out more hp than a 4 stroke of the same cc...
Ultimately I feel it falls more down to pride when someone says give me a Victa 2 stroke any day.. Are Victa 2 strokes better and/or more fuel efficient than a briggs or as refined as a Honda? I don't think so more like cranky loud and blow smoke!... But what they do have going for them is pride!...Pride in an Aussie made product that will still be cutting grass in how many decades later? as long as no one straight gases it that is ,who has time to mix oil in fuel nowadays (apparently being such a big job and all?)...

Of course none of this applies to the new age throw away society, if it needs new blades throw it to the tip and buy a new one to easy!..The future will be old men telling their grandkids about the good old days when we made our own Victa 2 strokes here in Australia of course they will say what's a two stroke? and your crazy grandpa! haha.....

Sparker, You got to remember some these users are the same ones that strike a match to look inside gas tank.

They are just too lazy to use their minds as they think everything should be automated for them.

Each type of engine has it place when it comes to the suitabilities for the job to be done that why diesel are the predominate engine style in large farm equipment and kerosene (Jet Fuel) engines in large aircraft.

Another determining factor is fuel availability, Some areas only have one type of fuel available so equipment chosen to meet this condition.

It is often a question of what you like, what you don't like, and how strongly you dislike it. Two strokes can be quite usable provided you don't mind mixing the fuel, being surrounded by noise emissions rather like an old cab that is way past its use-by date, and getting yourself smoked on the hoof while you are trundling the thing across the grass areas. On the more positive side you can use them on outrageous slopes, though it is dangerous to do so.

I personally find 4 strokes easier to work on, and vastly more prone to staying fixed once you fix them. However if you rather like the idea of keeping a small tool-kit close to hand whenever you run your mower, a two stroke may be just the thing.

So far as durability is concerned, I think a good example of either type can last a very long time if you look after it. You may have to pay quite a bit of attention to the spark plug of a two stroke, but you certainly have to pay attention to keeping the sump full of clean oil with a four stroke. Emissions laws permitting, they both have their place. Personally I'm rather more comfortable with a two stroke engine on line trimmers, because I'm wary of mist-lubricated four strokes. That is just prejudice, though: a long time ago I was wary of fuel injected car engines, because the early examples were so bad.

I can tell one thing though some of the 4 stroke string trimmers are a real pain to work on. I recently worked on a Ryobi RY34442. In order to change the timing belt you need to disassemble the half shaft crankshaft by pressing it apart. It is the same if you need the piston out. I was here lucky as I have a 12T press.

The engine ran very strong after the repair to only it come back a week later with a severe lost of power. It had blown an oil seal and had destroyed camshaft bearing surface. The only way to fix it to short block which cost nearly 2/3 of the retail price of the whole trimmer not counting labor. They even sell the need engine internal parts individually here.

Here in the US the four stroke trimmers just don't seem to hold up to the demand users put on them. Some user have great results but most users have nothing but nightmares.

As well as a possible durability issue there is a weight issue with the 4 stroke line trimmers, AVB. A reasonable number of contractors use the Honda trimmers here, and seem to be quite happy with them. Others complain about the weight and price, but I haven't yet heard any reports of unreliability, with the Honda.

From this long, long distance I think perhaps the lousy performance of many 4 stroke trimmers and catalyst-equipped 2 stroke trimmers reflects the relatively short time since low emissions became mandatory. I seem to recall something similar happened when outboard motors were forced to have oil-free exhaust and low emissions, but with the outboards, the problems were overcome fairly quickly. My guess is that the same will happen with the trimmers. Meanwhile we in Australia will sit back and watch you guys suffer the pain so that we can share the gain once the new technology is properly developed.

Interesting input. Thanks. I recon I will keep 2 of each.

Hello ALL Contributors,

For me, this topic started by beloved Sean is a vexed one.
The context is not really about seeking a right or wrong answer -
it's really about whatever floats your goat.



However, I would like to say that for lawnmowers, the verdict is
now in favour of the 4-cycle - for environmental reasons.

However, the internal combustion engine has been so clever at re-inventing
itself, it's not a clear case at all. Will there be a 2-stroke renaissance?

Here is a great historical piece on Victa's 1970's claim that the
two-cycle is the best thing since the power mower was invented:-

https://www.outdoorking-forum.com.au/forum/ubbthreads.php?ubb=showflat&Number=66878

All very stroke of luck.
----------------------------
JACK

hard to see a two stroke revival CJack as it wont meet the next round of regulations, so as far as Victa is concerned, the mighty 2/- is finished , within a year or so the axe will fall and the blue haze will clear from our yards once and for all

theres still nothing like the smell on a sunday though , 2stroke smoke everywhere ........ now where my castrol R

2 stroke, Man
4 stroke, woman

I've just heard word that Briggs & Stratton have said that
they intend to phase out the Victa 2-stroke over the next few years.
The two-stroke lawnmower is dead in the water on the grass.

Woman are superior then ...
--------------------------------
Jack

Wow, end of an era. What 2 stroke mowers are on the market at present ?

Hi Paul

Thanks for recognizing the significance of the announcement.
It is the end of an era isn't it, and, not unexpected.

I think Victa is the last 2-stroke lawnmower manufacturer.
There is only one 2-stroke - a 'Corvette' shown on the Victa AUS site.
I don't think any 2-strokes are exported.

A slow, painful end.
------------------------
Jack

Funnily enough, I was looking at the Victa website yesterday just to see what 2-stroke mowers were still available.

The only 'domestic' rated one I can find is a '18" Commando Mulch & Catch'.

However each of the mower models available in the 'Professional Products' range seems to have a 2-stroke option.

None in the Bunnings-based 'Victa pro' range.

The last in Oz, but not the last in the world. Most of the South African manufacturers mentioned in THIS past thread offer at least one model with a 2-stroke engine option, usually a 106cc Yamaha MT110. Edit: But some further research reveals that Yamaha has now discontinued that engine, so it looks like the writing is on the wall in ZA too.
New Zealand seems to be the last remaining Victa 2-stroke export market, and the Kiwis do get the commercial Mastercut 460 MXP462, as well as the Commando 550 and Mustang MMX482 domestic 2-stroke models. See http://www.victa.com/nz , and I could find these models on NZ dealer websites too.

Victa has exported to South Africa in the past, but doesn't seem to now.

Hi Gadge

thanks for clearing that up.

When I looked at their international dealers, I have found it difficult
finding Victas. Example: the UK. Perhaps their list is out of date.

http://www.victa.com/au/where-to-buy/international-dealers

Cheers
-----------------
Jack

thanks all, what an amount of great info.
will a 4 stroke last if i constantly mow a lawn that is on a 45 dergree angle. wont the oil sit on one side and the other side heat up?.
Another question, if 2 strokes are being fazed out, i have a backyard with 53 2 strokes am i sitting on a gold mine.
if so i will try not to break anymore.
sean