2 strokes; Noisy smelly unreliable things or the very soul of motorcycling?

[Supermofo]

My pal bought a new one in 88 and only kept it a year.

How did he buy one in 88 when they didn't come out until 89?

Folk often got race bikes before road.
I remember the first race day exactly.
He was pissed off that I beat him easily on my YPVS 350.

So it was an early KR1 not a KR1S then.

[Yorick]

How did he buy one in 88 when they didn't come out until 89?

Folk often got race bikes before road.
I remember the first race day exactly.
He was pissed off that I beat him easily on my YPVS 350.

So it was an early KR1 not a KR1S then.

IIRC it was the full fat version. Cost him a fortune.

[mangocrazy]

He was pissed off that I beat him easily on my YPVS 350.

So you should. You had an extra 100cc over him, plus your YPVS was almost certainly tuned.

[Mr. Dazzle]

They're a thing of the past from my POV, never been "current" for me and therefore a bit outdated and shite.

Plus they always look and smell like they're broken

You're around the same age as Bob and I aren't you? Or did you start late?

I passed my test 2 days after my 17th Birthday in 2001. Back then, IIRC, you could just about still buy a Honda NSR125 and also the Aprilias and Cagiva Mito. And obviously a load of "dirt bikes" for want of a better term.

For me it was all about Jap 400s etc.

[KungFooBob]

JDM 400's, now we're talking...

[Supermofo]

Folk often got race bikes before road.
I remember the first race day exactly.
He was pissed off that I beat him easily on my YPVS 350.

So it was an early KR1 not a KR1S then.

IIRC it was the full fat version. Cost him a fortune.

Dunno then, although 88 would definitely not be an S as they weren't out till 1990. Owned all 3 bikes in our family and the KR1S was fucking mentalist. Plus every single bike mag laud it as the fastest 250 ever. Who knows, it's all good.

[Sadlonelygit]

My old PE400......proper man's bike
Twin shocks, drum brakes and indecently quick for an enduro bike of that era.
KTM 250 exc, did everything 10x better than the PE, but nowhere near as 'exhilarating'
NS400R. First bike that actually handled properly.......shame it only had LC power as standard.......that didn't last long though

[The Spin Doctor]

It's easy to forget that development of 2T bikes stopped at least 30 years ago. Had they not been effectively outlawed then, I doubt that 'today's' two strokes would be nasty smelly things - they'd be sophisticated rocket ships. The 2T engine has a number of advantages over a 4T - volumetric efficiency, weight, size and lack of complexity for starters.

There are still a few people developing 2T engines, and they are getting quite staggering outputs from small (c. 350cc) engines. But it's all 'beardy blokes in sheds'. If mainstream time and money had been thrown at their development who knows what we'd have today.

I'd love a truly modern 2T.

I seem to remember that Ford had been developing a lightweight 3 cyl 2T car engine, and had not only been getting great power but also surprisingly good fuel consumption and clean emissions (at least for the time). If my memory's right, it had a 4T bottom end and fuel injection.

[Mr. Dazzle]

If my memory's right, it had a 4T bottom end and fuel injection.

That'd be the biggy, cause it removes the need for the fuel/oil combo which is also the big issue for emissions. No smell though

Loads of these ideas were messed around with in the 1940s at the pointy end of aero engine build, before Jet engines made them moot.

Have a look at the Rolls-Royce Crecy.

[Rockburner]

It's easy to forget that development of 2T bikes stopped at least 30 years ago. Had they not been effectively outlawed then, I doubt that 'today's' two strokes would be nasty smelly things - they'd be sophisticated rocket ships. The 2T engine has a number of advantages over a 4T - volumetric efficiency, weight, size and lack of complexity for starters.

There are still a few people developing 2T engines, and they are getting quite staggering outputs from small (c. 350cc) engines. But it's all 'beardy blokes in sheds'. If mainstream time and money had been thrown at their development who knows what we'd have today.

I'd love a truly modern 2T.

I seem to remember that Ford had been developing a lightweight 3 cyl 2T car engine, and had not only been getting great power but also surprisingly good fuel consumption and clean emissions (at least for the time). If my memory's right, it had a 4T bottom end and fuel injection.

Direct Injection (injecting straight into the cylinder head volume) can do wonderful things to the efficiency and emissions on 2-strokes (one of my Uni lecturers was working on it in the mid-90s), I'm not exactly sure why it never became more popular: possibly at the time the very high-pressure injectors (ie, they have to resist the very high pressure within the cylinder head) were an issue? Or could be that the mileage gains weren't as high as hoped (obviously if you're providing twice as much fuel per rpm speed compared to a 4-stroke, (a power pulse every revolution, instead of a power pulse every 2 revolutions) then each pulse of fuel needs to be half as much in order to maintain fuel-usage parity: that's running extremely lean).

[KungFooBob]

I think the modern two smoke dirt bikes like yozza's are direct injection.

Aprillia had a small capacity scooter that was direct injection too.

[Mr. Dazzle]

Loads and loads of cars, both petrol and diesel, are direct injection now. Wouldn't have thought it's a major blocker any more.

[Yorick]

I think the modern two smoke dirt bikes like yozza's are direct injection.

Aprillia had a small capacity scooter that was direct injection too.

Yip. All the KTM stable are fuel injection.
My pals had the carb KTMs and they all say the EFI jobs run better with better fuel injection.
And now they all run the oil fuel pump rather than premix.

[KungFooBob]

Had a Google, the Katooms are just fuel injected (rather than carbed) not direct injection (in to the cylinder head).

[Ian]

I love my 2 strokes but they were a dead end when we got 600 sports bikes reving to double the revs a 2T would do.

While 4T only revved to 9k a 2T offered twice as many power strokes for the same revs but even my lowly 93 ZZR would rev to 14k so that advantage was lost long ago

Maybe modern ones with direct injection and bottom end lubricated like a 4T could be a winner but development is all going into electrics and hydrogen now.

Sigh

[Cousin Jack]

Loads and loads of cars, both petrol and diesel, are direct injection now. Wouldn't have thought it's a major blocker any more.

IIRC direct injection in it's early days ran into significant problems. As you say, now solved and commonplace today, but all today's development is going into electric or hydrogen.

[cheb]

I'm a relative latecomers to 2Ts, all the bikes I had for practical reasons were 4T. My first proper 2T was a KX250 in 1989, my first road legal was a CRM250AR in the early 2000s I think. I've sold both the TDR and the DTR because I wasn't riding them enough to keep my hand in. I'll miss the noise and smell. If I was to buy another one it'd be a single cylinder air cooled job, maybe a DT100.

The last book I bought, delivered today, is Jan Leek's MZ, The Racers.

[Bustaspoke]

Like most of my mates I had 2 strokes,FS1E/GT250/250X7/RD250/250LC but it's the mid 80's since I last rode one.About 8 years ago I was thinking about buying one again but I got a shock at the prices people were asking.Maybe it's a nostalgia/rose tinted glass's thing but when my mates & me talk about the old 2 strokes from our formative years it's usually positive memories. Ironically I was talking to one of my mates this morning & he's thinking of selling his 350YPVS,I had a think about it & decided to stick with my old SV650.

[Skub]

They are shite,slow,evil handling,thirsty,often fragile and smelly.

I love them.

[Mr. Dazzle]

Loads and loads of cars, both petrol and diesel, are direct injection now. Wouldn't have thought it's a major blocker any more.

IIRC direct injection in it's early days ran into significant problems. As you say, now solved and commonplace today, but all today's development is going into electric or hydrogen.

Thing is, systems like direct injection or the Ford type 3 cyl engines are much more like 4Ts in terms of mechanical complexity. Loads of companies have made announcements about, or patented, new 2Ts which pass emissions regs, but they typically use 4T style bottom ends, forced induction (necessitated by the former) and often some sort of valves/cams. Therefore they end up being just as heavy, complex and expensive as 4Ts and the 'classic two strokeness' people seek isn't there. Nor is the motivation for OEMs to develop them.