2 stroke vs 4 stroke

[Tank]

Asking this in General as opposed to scooters to get a wider audience.

Im looking at getting the missus a scooter.

Options engine wise are a 110 2 stroke (the PGO) or a 125 4 stroke (Suki and others).

Now our main problem is that we live on a BIG ASS hill - so the scoots got to have a wee amount of guts - a 50 wont make it (test rode and it was doing a dangerous 15km on the hill flat out).

I know nothing about 2 strokes - will this have more power or less? (I know Big Dog has the PGO 110 2 stroke and he seems to get along OK).

Any help will be awesome.

Tank

[Badjelly]

I know nothing about 2 strokes - will this have more power or less?

Even a notorious 2-stroke hater such as myself has to admit 2-strokes generally have more power for a given capacity (on account of the fact they fire once per revolution rather than once per 2 revolutions). Why do you think they let 250 4-strokes race against 125 2-strokes in MX?

[Devil]

Here's the theoretical side of it.
Using the same capacity, a two stroke produces a similar amount of power per engine cycle (two piston strokes, or four piston strokes). It just does it twice as often (every two strokes instead of four) so, a two stroke generally on paper has almost twice as much power as a similar capacity four stroke.

I'm looking into a 125 4 stroke scooter as well, will have to test it though.

[MisterD]

Also worth bearing in mind that 4-strokes are generally higher compression and therefore give you a bit more torque.

[Flatcap]

Two strokes smell better

[enigma51]

Two strokes are smaller and more compact engines so they tend to be lighter.

4 stroke is easier to maintain as you just fill it up where a 2 stroke you actualy have to check the oil every fill up.

[Tank]

I'm looking into a 125 4 stroke scooter as well, will have to test it though.

Can I ask what ones you are looking at? - Im currently leaning to the AN125 Suki - at least I know I will get parts, and the dealer has been awesome to date and Id like to give him my business if reasonable.

[scracha]

2 strokes belong on chainsaws and race tracks. Too much of a PITA for regular road use IMHO unless you actually like reboring engines, fannying about with 2 stroke pumps/premix and changing spark plugs.

[Devil]

Can I ask what ones you are looking at? - Im currently leaning to the AN125 Suki - at least I know I will get parts, and the dealer has been awesome to date and Id like to give him my business if reasonable.

The AN125 and the UZ125.
Is it the AN that comes with alarm and 12V socket?
Would buy from Holeshot. I'd got the 4 stroke way just for maintenance reasons.
Will go speak to Rob in the service dept first because I know they've had issues with some of the 125's, but I think they have been discontinued (the particular problem model).

[EJK]

The AN125 and the UZ125.
Is it the AN that comes with alarm and 12V socket?
Would buy from Holeshot. I'd got the 4 stroke way just for maintenance reasons.
Will go speak to Rob in the service dept first because I know they've had issues with some of the 125's, but I think they have been discontinued (the particular problem model).

the UZ125 has the alarm and the 12v socket.

I heard (and test rode) a UZ125 and...... it's a good scooter. Maybe the best* in the range. It's fuel injected too.

Well I've got two PMs about 100cc 2 Stroke scooter, I'll forward it to you in a sec

best*: light, quick, and I presume reliable

P.S. How about Italian Piaggio Fly 125? It's in the same price range

[C_A]

2 strokes belong on chainsaws and race tracks. Too much of a PITA for regular road use IMHO unless you actually like reboring engines, fannying about with 2 stroke pumps/premix and changing spark plugs.

they're hardly any worse than any engine if you treat them right. scooters are hardly going to foul plugs if you use decent oil and dont ride everywhere at idle.
plus 4 strokes have all that messy valve gear which you jsut know will fail given the revs scooters pull (who doesn't ride them at the absolute fastest they'll go on the flat, then even faster down hill?)

two stroke all the way.

[quallman1234]

With reference to scooters.

Mainteance will be the same comparing the two scooters.

Fuel consumption will be very similar (110cc 2 stroke vs 125cc 4 stroke), however you will have to add a 1L of oil approxmentally 800 - 1000km (Scooter 2T oil is cheap so not that bad however racing 2T oil used in high reving scooters are not cheap 25 $ + a litre)

The 2 stroke definitely will be quicker.
And none of this bullshit changing sparkplugs crap every now and then, all you need is 2 stroke oil and petrol and she be fine! (maybe an 8$ spark plug once every 2 years might be good tho).

Lots of people think 2 strokes are less reliable than 4 strokes. Yeah correct if we were living in 1960 - 1980's . The fact of the matter is they are just as reliable if not more so these days.

4 Stroke riders just can't hack that we make more power per cc than them

[F5 Dave]

Also worth bearing in mind that 4-strokes are generally higher compression and therefore give you a bit more torque.

Wrong & also incorrect. Their BMEP may be higher but it has little to do with the compression ratio. Dynamically 2 strokes can have a fairly high compression ratio, their static measurement isn't really relevant.

Torque at the rear wheel the higher horsepower unit will have more, but I suspect you are misusing the word talking about power spread. Trials bikes all used to be 2 strokes as they could provide a better spread of power than a 4 stroke, emissions laws changing that. Depends on how any engine is designed/tuned.

2 strokes belong on chainsaws and race tracks. Too much of a PITA for regular road use IMHO unless you actually like reboring engines, fannying about with 2 stroke pumps/premix and changing spark plugs.

Valves belong in toilets, you're living in the dark past. Even 60s Vespas aren't as black as you paint it, modern Jap stuff is as reliable as anything else. Chinese stuff, good luck you'll need it. European, hmm. . .

On the other side of the equation you should also ask yourself how your wife will cope with small scooter wheels over wet manhole covers in the dark. They have their place, but it really depends on what your local roads are like. I would consider a large wheel bike for around my local suburb hilly roads.

Don't skimp on decent gear with armour, she will need to understand she has to wear heavy boots & stuff even for short trips.

How long will it take to pay back the initial investment considering she may not like it & may take the car when it is raining?

[MisterD]

Wrong & also incorrect. Their BMEP may be higher but it has little to do with the compression ratio. Dynamically 2 strokes can have a fairly high compression ratio, their static measurement isn't really relevant.

Torque at the rear wheel the higher horsepower unit will have more, but I suspect you are misusing the word talking about power spread. Trials bikes all used to be 2 strokes as they could provide a better spread of power than a 4 stroke, emissions laws changing that. Depends on how any engine is designed/tuned.

No, I'm not talking about power spread. Put it this way, I have two scooters with similar 187 ish cc rating...the 4s will 'engine brake' far more than the 2s, and that 2-stroke is set up for torque and rideability rather than outright power (no chamber).

[F5 Dave]

. . . . Put it this way, . . .

Why put it that way? it doesn't illustrate anything more than your 4 stroke has more engine braking. My point was that compression ratio isn't the relevant factor.
Comparing 2 engines of similar size is all very interesting but does not a study on the engine genre make. Lets say we use a Italjet Dragstar or whatever they are for the 180 version. That will create more torque than any 4 stroke scooter of similar size I bet, just in the way a peaky R6 can create a lot more torque than a 1340 Harley. Just the word Torque is highly misused.