Scooters?

[bio-smear]

You need this. Look at the pipe on that thing.

Wait, hold on. Talk to Sam:

[f2f]

Is there really that much of an environmental difference between the two stroke and four stroke. I heard that the most recent two stroke engines are not really that much more worse for the environment as compard to a four stroke. One of the reasons, I got my scooter was to help the enviroment. The four stroke just sucks up hill.

the problem of the 2-stroke is that it burns lubricant as well as fuel (4-strokes do too, but to a much lesser extent). i don't know about recent innovations, but where i grew up, the east german 2-stroke cars (trabant and wartburg) were definitely the dirtiest cars on the road:



also, from driving two-stroke karts, i can tell you my clothes are consistently dirty from all the oil that gets spewed from the exhaust.

it's definitely not a clean system, but if you know a development of cleaner burning 2-stroke let us know, i'd like to read about it.

[encore]

but if you know a development of cleaner burning 2-stroke let us know, i'd like to read about it.

I haven't seen an article. Just things I've heard from others. Maybe some it was bullshit.

This one is pretty cool:

[bio-smear]

2-strokes get a bad rap for pollution, because many of them aren't tuned properly for clean combustion. There's no getting around the fact that the fuel they used must be mixed with specialized oil, whether it's premixed or injected during induction. The crankshaft and main bearing are lubricated by the atomized fuel being inducted through the crankcase and then into the cylinder. It's rather clever and bombproof compared to using valves.

There's really no comparison between a Trabie/Wartburg and modern 2-strokes as far as pollutiveness. Those things were shit, burning shitty oil. Today's 2-strokes use synthetic oils and the newest ones are even fuel injected, making for the perfect mixture setting for the atmospheric conditions. A properly leaned mixture on a 2-stroke makes for a super power-to-weight ratio, and they are not messy.

We run a Rotax 503 on one of our planes and it is an exceptional engine.

[counterfeitfake]

I might be new to civilisation.

But ride that thing through our village and me and the guys are going to throw spears at your faggoty ass.

Yeah, my main thought on the huge scooters is you should get them if a real motorcycle would be too straight for you.

[f2f]

i like the rattler. doesn't seem to be sold in canada...

as for 4-stroke being low on power, i'm pretty sure sooner or later somebody will figure out how to use more, smaller cylinders for the same displacement and increase the rpm.

[Tippster]

... if you know a development of cleaner burning 2-stroke let us know, i'd like to read about it.

http://www.greencarcongress.com/2006...l_piston_.html
http://www.greencarcongress.com/2005...veloping_.html

http://www.autobloggreen.com/2008/05...stroke-engine/


Nothing for bikes, though.

[encore]

For the under $3000 club, this one is pretty slick looking:

2008 Aprilia SR 50 R Factory

[encore]

i like the rattler. doesn't seem to be sold in canada...

I test drove one last Saturday. It was great, but seemed noticably louder than the KYMCO People 50 and the Genuine Buddy 50.

[El Chupacabra]

For the under $3000 club, this one is pretty slick looking:

2008 Aprilia SR 50 R Factory

That's the one I'm googling up on now. Friend has one here in Reno; I'm going to go check it out.

Also found a possible source for new leftover ones for ~$2200.

[f2f]

thanks, Tippster. off to read.

since we've digressed into 2-stroke territory, listen to a single cylinder 125cc honda 2-stroke in all its glory at 14000rpm max (noise warning, turn speakers down):

[counterfeitfake]

as for 4-stroke being low on power, i'm pretty sure sooner or later somebody will figure out how to use more, smaller cylinders for the same displacement and increase the rpm.

Um. Do you know what you're talking about or are you just making shit up? Honestly, not meaning to offend.

[f2f]

not meaning to offend.

but you did anyway

edit: you didn't ask me to explain myself, so i won't. i'll let you figure out on your own why more cylinders per the same displacement equals more torque.

[Tippster]

Ummm... I thought it meant less torque but more HP....? Kinda like a 1000 V-Twin has more torque than an inline 4, but less ponies and lower redline?

Pretty sure they both have something to do with mass and inertia, but I'm a natural blonde.

[f2f]

meh. torque, power, it's all the same

/in the blonde club now too.

[Rideski]

Thanks for the speaker warning f2f, that would have blown me right out of my chair...You never passed him?


This has been on my wish list for a while now as a first bike/city commuter.
But I have a rather long wish list...

[bio-smear]

Power is nothing without torque
The inline 4 has plenty of torque, it just occurs at 11,000 rpm or whatever the peak of the powerband is for that engine, which means it feels kinda sluggish off the line and in the lower rpm range of each gear, unlike a V-twin or a thumper. Remember that torque is a rotational force applied at a distance...if I remember correctly they used a strange way to determine this for autos and motorcycles, like horsepower delivered over so many feet. There is a standard I think.

The biggest factor in in torque is the stroke of the piston. Twins and thumbers tend to have longer strokes for a given bore, meaning the reciprocating mass gains more interia.

[Tippster]

Ummm...Rideski, that bike's not street legal, at least not in any jurisdiction I know. Needs headlights, taillights, a mirror, and turn signals.

http://powersports.honda.com/motorcy...delId=CRF230L8

[counterfeitfake]

It's just that it's so hard to tell on the internet...

There are a lot of variables and so I'm not sure what you're getting at. There must be some point at which you get diminishing returns out of adding more cylinders. It's common that at the same dispacement, a 2-cylinder engine produces more torque lower in the rpm range than a 4-cylinder, but the 4-cylinder can rev higher and so can usually produce more power. I am not totally sure why this is- I guess that it has to do with piston mass? But the more cylinders you add, the more frictional surface area you have to deal with, I suppose.

Anyway, you just do not see 5-cylinder motorcycle engines, so there's got to be some reason for that.

What this all has to do with 2-stroke vs 4-stroke, I am not sure.

Unrelatedly, I thought that the biggest factor in an engine's redline was the strength of the internals, including the valve springs.

[Rideski]

You're right, I thought it was the same as this one but just less cc and money but it's not.

[f2f]

Thanks for the speaker warning f2f, that would have blown me right out of my chair...You never passed him?

that's not me: i can't fit in that kart, which is made for small people. my wife fits in it.


the particular track is too turny for TaG karts to pass each other easily.
http://maps.google.com/?ie=UTF8&ll=3...05236&t=h&z=18

[f2f]

Anyway, you just do not see 5-cylinder motorcycle engines, so there's got to be some reason for that.

long time ago i was reading about a small-displacement 8-cylinder engine from a japanese motorcycle manufacturer that was supposed to deliver fantastic results. i was young and impressionable

i am easily impressed by small things, 1.5 litre 1000+bhp formula 1 turbo engines are another example. so if someone wants to build a 4-cylinder 50cc engine in a manner not dissimilar to a swiss watch, i would love to see whether the results are sufficiently impressive.

the argument behind smaller cylinders is the same as the one for multiple spark plugs per cylinder (alfa romeo twin spark, for example): better burning of the available fuel. the argument for more cylinders is a better power curve for the entire rpm range.

edit: that said, lots and lots of (very small) moving parts may indeed negate the diminishing returns, as you said.

[Rideski]

Originally posted by Roo:

[Badger]

I just replaced my 1967 Honda CT90 4-stroke, 90cc trail bike with a 1975 Kawasaki F7 2-stroke, 175cc enduro.

I never bothered to figure out the mpg for the Honda. It was a lot. The F7? Also seems to be a lot. Can't imagine it will be any less reliable - the whole engine appears to have like six parts. It's loud, but not totally obnoxious if I keep the rpm's down. It does smoke, so I try to keep it moving - but the 40-year-old Honda burned its share of oil, too. Top speed seems to be about 55-60 mph (the CT topped out at 40ish).

Bottom line: $500 will get you a decent bike. And, old bikes are way cooler.

[SuperGaper]

Honda dominated Moto GP when they went to four strokes with a 990cc V-5, 3 forward, 2 rearward. Put a little more mass toward the front tire.

http://www.motorcyclistonline.com/fe..._gp/index.html

220 hp at 14,000 rpm, 345 pounds!