[GRBLDeveloped]

That's interesting about the 2 stroke engine being the issue for pollution.

"In 2014 a study published in Nature Communications found that VOC emissions (a variety of carbon gases that can produce smog and harm human beings) were on average 124 times higher from an idling two-stroke scooter than from a truck or a car"

Though this quote does make me wonder, what about when each vehicle are in transit?

[horsawlarway]

2-stroke engines are designed to have the oil mixed with the fuel - they burn it as part of operation. It makes them pretty terrible from an emissions standpoint. See: https://en.wikipedia.org/wiki/Two-stroke_engine#Lubrication

[bradfa]

There is now fuel injected 2-stroke engines which will pass the current Euro4 emissions rules for dirt bikes and motorcycles. There's no reason that a small 2-stroke can't have lower emissions today. It's clearly more expensive to make a fuel and oil injected 2-stroke engine than a simple pre-mix 2-stroke, but it's possible and then you get all the benefits (and even more!) of a traditional 2-stroke in terms of power output, you just have a little computer and some injectors instead of a carburetor.

[luma]

One of the major benefits of a two stroke engine is the simplicity of the design, which lowers cost, reduces size, and increases reliability. Your proposal is a net loss on all these factors.

A far better solution is to replace these sorts of things with battery powered electric solutions.

[bradfa]

2-strokes output more power. This isn't my proposal, this is a thing which exists in the world today, produced by various different engine manufacturers for sale to the public today in motorcycles.

Miniaturizing it to work on a hand-held lawn care device is just an engineering task.

[snovv_crash]

It needs a high pressure rail with fuel pump, electronic injection and ignition control. This adds considerably to the cost, which when you take it into the engineering optimization problem, starts pointing to electric plus batteries for these small sizes. You need about 100cc before it makes sense to start looking for fuel engines, or some application that requires really high energy density for long endurance at light weight (eg. surveillance drones).

[sojournerc]

Intuitively I think an injected engine would be more reliable. Gummed up carburator causes the pull-start blues for me frequently on my chainsaw when I haven't used it for a while. I do get a nice arm workout though.

[tzs]

It was the same with my lawn mower. It only gets used maybe 6-8 times a year. For some recent years here were how many days it had been idle before each use: (245, 22, 14, 15, 14, 33), (258, 24, 12, 13, 17, 11, 38, 71), (167, 21, 21, 20, 15, 61).

Two simple things fixed that:

1. I switched to gasoline that does not have ethanol added.

2. Once every 2 to 4 weeks in the off season I start it and run the engine for a minute.

The container I use to store gas holds about two years worth and the mower runs fine on the the two year old gas. I do add fuel stabilizer. The bottle of that claims it is good for 2 years but my previous bottle was 6 years old when I replaced it and the mower was fine on 2 year old fuel with 6 year old stabilizer.

If you live near any body of water big enough to attract boats you might try at marinas. CENEX also often sells it. Here's a site that can help you find it locally if you are in the US or Canada [1].

I do not do any winterizing procedure for the off season. I asked the repair place I took it too one year when it would not start before I started doing #1 and #2 if winterizing was necessary if you were running it occasionally, and they verified that you only need winterizing if it is going to not be used.

[1] https://www.pure-gas.org/

[mizzack]

100% agree on the ethanol-free gas to reduce carb gumming.

For overwintering, I just detach the hose after the fuel filter and drain the remaining mower fuel back into the can. Or, on small push mowers where this isn't possible, use the fuel shutoff and just leave the gas in the tank.

Then run the mower until it dies. Doesn't take more than a minute.

Finally, unscrew sparkplug(s), pour a teaspoon of motor oil into the cylinder (keeps rings from seizing/rusting).

Leftover gas in the can gets put into vehicles at the end of the season so I'm not storing stale gas.

[feet]

I'm willing to bet that computer controlled fuel injection wouldn't solve the issue. It may lower emissions slightly but two strokes still require lubricant to be mixed with the fuel, I'd bet my hat that's where the high VOC emission is really coming from. They're constantly burning oil, literally.

[bradfa]

The oil is injected separately from the gas. So only as much oil as is needed for the engine load and speed is injected, which allows varying the oil mix as low as even below 100:1 compared to normal pre-mix concentrations of 40:1 or 50:1. So the amount of oil burned is significantly less on the injected 2-strokes as it’s only injecting what the engine needs for lubricity and nothing more.

[feet]

That's interesting, I wasn't aware they get injected separately. While this would decrease VOC emission greatly, I can still see these engine designs being higher emission than a comparable four stroke although I may be wrong. I'm not a mechanical engineer.

My reasoning is that oil still gets burned, likely at a higher rate than any oil that gets through on the four stroke. It would be interesting to see if two strokes could be redesigned to place the oil outside of the combustion chamber, I think that would be a serious game changer for ICEs.

That being said, I'm definitely an advocate for moving away from combustion altogether.

[horsawlarway]

Interesting - At least in my area most of the gas weed eaters available for sale are now 4-stroke. Wonder which will end up being more prevalent.

[bradfa]

For a homeowner, a 2 or 4 stroke gas engine has no compelling benefit these days over a cordless electric string trimmer. The price of the electrics seems to be low enough now and carry enough energy to handle pretty much any single family home. But for a lawn care crew who may cut 20+ lawns a day, they will need a heck of a battery solution for string trimmers or leaf blowers, either in terms of battery capacity or in mobile recharging ability (which surely would end up being a gasoline or propane generator on the trailer with the lawn equipment).

[horsawlarway]

Personally - I think electric is still a fews years off being usable for yard equipment.

I live in a metro, but my property is about an acre. I bought an electric lawnmower/weed eater when I bought the house. I used them for a year, then donated them and bought gas (4 stroke for both).

The problems I encountered: Batteries are expensive and they just don't last nearly long enough (both charge and life). To do a real pass on my yard without waiting for a charge cycle, I would have needed about 4 batteries for the trimmer, and 8 for the mower. I do live in a heavily wooded area with a large number of vines (and kudzu...) but still - that's nearly 1000 dollars in batteries alone. I opted to wait, and stick with 4, but it means what was previously 4 hours in the yard is now 4 hours split into several sections - an all day affair.

Even with the above, I would have probably stuck with the trimmer (the mower was just garbage), except I had two batteries fail in the first year. That's just an unacceptable extra cost for yard work, and FAR eclipses the entire amount I've spent on gas for the mower/trimmer combined over the last 3 years I've had them.

So... No. Frankly I don't think they're there yet. It's very close, but it's slower, and frankly - outrageously more expensive.

So I'm going to wait for cost to come down, and regulation to address battery interoperability in this equipment (hah... as if our government would actually do something useful).

[throwaway0a5e]

>For a homeowner, a 2 or 4 stroke gas engine has no compelling benefit these days over a cordless electric string trimmer

Cost.

I would have gone electric if I could but seeing as I don't obsess over my lawn (i.e. I let it grow out enough before cutting it back that most HNers would be hand wringing if I were their neighbor) there's no amount of mental gymnastics that makes it a sane tradeoff. I'm not gonna double the cost on something I run maybe 20min/mo. If I were one of those people who bought overpriced premium equipment I didn't need then it might make sense.

[michaelt]

Do y'all not have corded electric mowers in America?

Here in the UK, an entry-level petrol mower is £150+ while an entry-level corded electric mower is only £50. They're also much lighter, which is great for ladies and kids. And they start really reliably, even if they've sat in a shed all winter.

[Unklejoe]

Corded electric mowers are very rare in the USA. I live in a suburban neighborhood in the North East and have never seen one in my life. I see some battery powered ones though.

I wonder if it’s due to our outlets being 120V? We’d be limited to less than 2.5 HP with a normal outlet, whereas gas push mowers typically have engines in the 5-7 HP range.

[richiebful1]

We certainly have corded electric mowers. I cut about half an acre with one and it's great. I find it performs better than a gas mower in higher grass (I generally cut once every two weeks).

[soco]

If you have it already, I understand. But if you started from scratch, or if your existing mower died? It might be a slightly different decision. Electric costs more indeed but your own ears, nose and lungs are important as well.

[throwaway0a5e]

I was starting from scratch at one point. Cheapo mower was $115 and weed whacker was $100. The greenworks combo that would have done the equivalent job was $~200 more for a smaller mower. This is comparing new vs new. I would up watching the internet classifieds and getting a free gas push mower making the cost discrepancy even more. I have yet to have starting issues with any of it and I don't do anything special other than do my last mow in October and first in April/May

I could do without the noise but I own fancy Bluetooth hearing protection for other reasons so that's really a non-issue. A little bit of exhaust every 3-5 weeks in the summer is just a non-issue in practice. I'm sure if I had some ideological reason to care a lot I'd find it more annoying but I don't so...

I have a friend who has the whole 40v kit. In retrospect I definitely made the right decision because his stuff doesn't have the requisite power/duty cycle for my "it's been a month and I have company this weekend, time to mow the lawn" use case and the noise of the gas stuff is less of an issue when it's a monthly thing and not a weekly thing.

[rascul]

I have two trimmers, one is a four stroke and the other is battery electric. The gasoline trimmer is generally a rarely used pole saw now because I can trim the whole yard without killing the small battery. It's easier, lighter, and quieter.