"Too bad its not a 2-stroke"

Something I have wondered about for some time. So I’ll ask and see what the response is.
I see a lot of desire for 2-stroke motorcycles, and some scooters, on this forum. I am from the USA, but have owned and rode motorcycles in a number of countries. Always 4-strokes - except for a '72 Kawasaki but that was a fluke…a very very fast fluke.

Is this 2-stroke preference a European thing?
Is it because most of the folks on here are younger and into the “sport-bike” racer style?
Is it that you like the sound of a 2-stroke rather than a 4-stroke?

This time I’m being serious, not judgmental.
You like 'em…thats fine. I’m just curious why?


I prefer 4 strokes as a rule, but I have a soft spot for 2 strokes… As a teenager I rode a lot of 2 stroke 125 and 250 off road bikes all over farm tracks and dirt roads etc. in Africa and so for a while 2 strokes were all I ever knew… I think if you ask most petrol heads what they like about 2 strokes it’ll all boil down to two words, power band… that glorious slice of rev range where everything sings and goes like hell… apart from that it’s the “no valve” simplicity of 2 stroke engines, the sound, the comparative lightness, the “tunability” for gear heads, power to weight ratio and for me anyway the smell, “the smell of victory” to quote someone or other…

the reason boy racers like 'em is easy, they’re making power on every down stroke meaning they roughly work out to a shade under twice the power output of a 4 stroke of the same capacity which is why a lot of enduro race series race 250 2strokes against 400cc 4strokes for example… In Taiwan 135cc or 125cc two strokes if well tuned and maintained effectively fill the non existant “250cc class” gap that lies between dull 125 4strokes and 400cc “big bikes” and they do it on the cheap since the 2 strokes are all way long in the tooth in Taiwan…

for encyclopedic 2 stroke knowledge though you should really ask redwagon… what he doesn’t know about building and tuning 2 strokes is, well, non existant…

You had a '72 Kwaker 2-stroke – I’m guessing an H1 500 triple or the whatever-it-was 750 version – and you’re asking why people want strokers, even if they are tiny? :laughing:

To me the 2-stroke is the perfect choice for taiwan. Especially since theres a huge barrier between most of us and getting a “real” bike, a small 2-stroke gives you the option of being able to ride relatively cheaply and still having decent performance. For me the disadvantages of 2 strokes are far outweighed by the advantages, even though they are a huge pain to maintain and fix. I heard somewhere that new 2 stroke technology could produce more reliable, cleaner engines. Mabye in the future 2 strokes will be revived. Just have to get more people to accept the “overgrown lawnmower” noise :wink:

Yep…a MACH 3 or 5 or something like that. 500cc triple. Like I said, it was fast. I had too many 4-stroke habits and just never got comfortable with it.
I hated that darn front wheel floating up when accelerating hard…in 1st…in 2nd…in 3rd…sometimes in 4th and that meant it was clocking over 110mph or so…not a good thing to experience for me. When it hits its torque…up she’d float.

Just too used to a lower torque range. At that time I was riding a 450 Honda and a '68 650 BSA Thunderbolt (the 1 carb model).

Like I said…just curious as to the reasons. Some god ones coming out.

Here’s an advert for the very bike. I loved that starburst emblem on the tanks.

I was going to say power to weight ratio, which in a small-bore bike is all-important. Once you start getting up over 400cc a 4-stroke starts to gain in terms of output for weight or volume (by this I mean the external volume of the whole engine/transmission package, not the cylinder volume). Under 400cc no 4-stroke will match a 2-stroke in either department. It’s also very difficult for a small displacement 4-stroke to match the 2-stroke’s torque output except in a very high-revving design, something anyone who’s ridden a 250 Ninja or Hornet will understand immediately.
OTOH, once the capacity gets up the 400cc range a 2-stroke loses some of it’s competitive edge wrt to power/displacement because the ratio of port area to cylinder displacement falls as they get larger. The only way to combat that is more cylinders of smaller displacement. Not that I would mind owning a 500cc 2-stroke triple or four of course, but I’d like someone else to pay for the gas!

BTW, a 2-stroke does not get quite double the output per unit displacement as a 4-stroke because the compression ratios possible are much lower, and a fairly significant portion of the intake charge goes out the exhaust port unburned. Also it’s not possible to rev a 2-stroke of similar displacement to similar revs as a 4-stroke because the time during which it’s possible for it to breathe is significantly shorter for a given rpm level. This last limitation has been reduced with innovations like uniflow scavenging, but they sadly never caught on, at least in gasoline engines.

Thanks for the kudos Plasmatron, but I’m a mere dabbler in these things. Without the work of Gordon Jennings we’d all still be groping around in the dark. :notworthy:

I grew up on 4 strokes, never in my life have I had the opportunity to play around with 2 strokes in the AZ desert except for dirt bikes, but you can’t run those on the street. So when I came to Taiwan, the first thing I wanted to buy was a 2 stroke motorcycle. 2 strokes can’t be found back home anymore. I remember watching GP Moto back when they were riding the 500cc 2 strokes. I thought they were amazing. Yes they were, and so are the bikes now. 4 strokes have always been the future, but since 2 strokes are still legal here in Taiwan, I wanted to get one, and play with it, and see what they are all about. They are fun, and easy to work on, but on the other hand they are not as reliable as 4 strokes, and they pollute. When my NSR is running just right (which is rare he he) it just sings to me, with a beautiful drum beat, it’s awesome, and the power band is always there. In the small cc motorcycle class, under 250cc, 4 strokes have nothing on 2 strokes.