The 2 stroke Engine

[Grant]

If anyone (Like Me) is fascinated by the 2 stroke engine then this must be watched, included is the 2 stoke diesel V8's etc.. brilliant, the best sounding engines are 2 stroke in my opinion, have a look and post your thoughts and comments >> https://www.youtube.com/watch?v=JlVNHqLxBnk" onclick="window.open(this.href);return false;
Grant

[Steve Payne]

Agreed on the sound, I used to have a Kawakami KH400 a few years ago. I would sometimes go out to the garage and just fire it up and run it to here the noise and smell the fumes.

Some aircraft engines used to be diesel two stroke.

Steve

[Kevin Birch]

Fantastic, but they have missed out one incredible 2 stroke, the18 cylinder , 36 piston, triple crank Napier deltic engine, which also has a great sound track.
The Deltic loco had 2 of them for good measure, and remember them coming screaming down the line with both engines on full throttle.

https://en.wikipedia.org/wiki/Napier_De ... mation.gif

[Dion]

Pity they did not include the Commer TS3. Amazing engine, opposed cylinders, two stroke diesel with blower.
https://www.youtube.com/watch?v=p8k35_153Vw

[aslef]

Seeing a Deltic fire up from cold is an impressive sight Kev,2 enormous plumes of exhaust which if no wind was around formed a V over the loco.As I remember each loco carried a nameplate with the northern based ones named after regiments while the Kings Cross ones were named after racehorses.
Magnificent machines with,as you say,an incredible exhaust note.
They don't make em like they used to!!

[Barrie]

Why haven't two-strokes been more popular?
I seem to remember something about lack of lubrication on a trailing throttle.

[Grant]

Thank you for the all the replies

[Grant]

I seem to remember something about lack of lubrication on a trailing throttle.

Correct Barrie
It's on the over run, like coming down a hill with the throttle closed and the engine revving more than should be in relation to the throttle position, therefor not supplying enough 2 stroke oil to lubricate the cylinders, but I've never had issue's but I do have a lot of mechanical sympathy ... but this is not the reason they were not more popular.. as usual the tree huggers and the USA have gotten them outlawed due to the emmisions

[Steve Payne]

Yes as Grant said Emissions are there problem, on some of the performance two stroke motorbikes of the 60s and 70s apparently 30% of the fuel went straight out of the exhaust. Not a problem when petrol was pence per gallon but that with increasing worries about the environment has meant that apart from garden machinery and some mopeds the engine is now out of favour.

Steve

[johnw]

I've always fancied a Trabant with expansion chambers!
https://youtu.be/qeDWemILPKs?t=110" onclick="window.open(this.href);return false;
Everyone looks expecting to see a bike go past!

[Grant]

I've always fancied a Trabant with expansion chambers!
https://youtu.be/qeDWemILPKs?t=110" onclick="window.open(this.href);return false;
Everyone looks expecting to see a bike go past!

Yes wicked John.. the noise is so good isn't it
Every 2 stroke should have expansion chambers or "spannies" as they call them.. As Stevey Payne mentioned his 400 triple.. the best sounding 2 stroke is the triple, this is because the firing is all offset, it gives the smoothest most beautiful sound, I have a drag bike (that most would have seen before), it was built for the drag strip and is 140bhp from old 70's 800cc triple cylinder Stroker (like Steve's one but bigger displacement), I bought it to take the engine out and mount it in a road bike, but as we know, I never got around to it so left it as was, this footage was taken back about 10years ago now, but I still have the bike >>>
>> https://www.youtube.com/watch?v=449Oh0flYtE" onclick="window.open(this.href);return false;

[johnw]

Very nice. Always good to hear the doppler effect though as it screams past, always a bit more dramatic with a 2 stroke. Would be a good idea to get a road bike chassis for it. Wouldn't take long to swap it in. Amazing how much a set of (Micron) expansion chambers could transform the bikes back then. The Silk bikes were interesting 2 strokes. Nice and light. I'm surprised 2 strokes aren't competitive in trials these days.

[Martin R]

Some garden machinery now use a 2-stroke engine but with valves, which give it a rather odd, almost miss-firing sound compared to the ported designs of old

[johnw]

That is interesting about the valves Martin. Was that a reed valve in the inlet tract, or a rotary valve on the inlet? I have had both of those on bikes from the 1970s. Both these bikes had an oil pump that metered the 2 stroke oil, which worked well and got rid of excessive smoking, and also delivered oil irrespective of throttle opening. Another interesting thing is that very early 4 strokes had a vacuum operated poppet valve on the inlet side. It is amazing how cheap engines have become recently, with a 4 stroke mower with electronic ignition now costing from £100 up. I recently bought a 2 stroke chainsaw from Aldi, £50 or so. It has got electronic ignition, but it is refreshingly noisy and crisp, decent amount of blue smoke, and a really nice rasp to it that has all the Tree Huggers twitching their curtains.

[Martin R]

That is interesting about the valves Martin. Was that a reed valve in the inlet tract, or a rotary valve on the inlet?

To be honest, I'm not sure. My old Yamaha 2-Stroke had a rotary valve (if I remember correctly) but when the garden equipment salesman described it to me, I felt he was describing 4-stroke type valves, possibly poppet valves.
A quick goggle has found this, complete with a diagram/video showing actuated valves: https://www.stihl.com/4-mix-engine-ligh ... power.aspx
Edit: To me it looks more like a 4-stroke engine taking its lubrication through a fuel-oil mix