Two Stroke Spotting-Cars (and the odd bike)

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 07:58

Here's a little selection, always sound better giving the revs a decent boot. The 2 Stroke Car is a bit of a museum piece these days, but a quirky and interesting crop to consider.

Here's a selection, also containing trucks and bikes.

And here's one from SAAB, niceish but well behind the most beautiful 2-stroke car ever made....which is

REgards Neil

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 08:27

So why do 2-stroke engines sound like.....well 2-stroke engines, and at idle sound ,(awful yes!), and like they are just about to stall. Well I found this explanation which sounded reasonable to me.....

Spoiler: show: "The biggest difference is the way the exhaust works. On a four-stroke engine, the exhaust valve is a "poppet valve", i.e. the familiar mushroom-shaped plug. This is pushed open by a cam, possibly indirectly, and for reasons of component longevity this is done fairly gradually. On a two-stroke engine, the exhaust port is a square-topped hole in the side of the cylinder, uncovered by the piston when it is travelling at near maximum speed.

The exhaust pipe on a two-stroke is used to super-charge the combustion chamber. The pressure wave from the opening exhaust port is passed through a divergent conical section of the pipe, reflecting back an inverted (i.e. -ve pressure) wave, which sucks burnt gas out of the cylinder. This burnt gas is then followed by fresh fuel-air mix, but before the port closes the original +ve pressure wave hits a converging cone, and reflects back as a +ve wave. This pushes the unburnt mixture back into the cylinder just before the port closes, giving the supercharging effect. The arrangement is called an "expansion chamber", and is notoriously noisy. It's difficult to silence well, partly because almost all of the exhaust length has to remain empty for the convergent/divergent parts to work, and often only a small "stinger" silencer is fitted on the tail of the exhaust pipe.

Four-stroke engines have made limited use of the divergent cone, known as a "megaphone" exhaust, particularly in the 30's-50's of the last century. However the fluffy opening pulse from the poppet valve does not work as well for this. In addition, four-stroke engines are generally expected to have a reasonably wide rev range, while two-stroke engines have been more associated with peaky race-based tuning. The megaphone approach tended to give too peaky an engine for road-based use (particularly given the three or four speed gearboxes of the time), while the similar peaky power delivery of a two-stroke (coupled with the 6-18 speed gearboxes which came in at the same time as expansion chamber technology) was accepted by the target market of riders.

Thats me confirmed as a member of the Dull Men's Club! as I already suspected on POTD

Regards Neil

white exec · Unread post by **white exec** » 18 Apr 2019, 08:43

Good grief, Neil. Never has the Hide button been more welcome!

Half way through, had almost given up the will to live.

Really looking forward to the total outlawing and demise of two-stroke bikes etc - fed up with their noise, smell and fumes, even on new ones. How come they've survived so long?

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 08:48

I can't be entertaining all the time Chris!

REgards Neil

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 09:29

I'll dig this out from the FCF archives. A two stroke kettle from the 1970's.

NewcastleFalcon wrote: 17 Oct 2018, 15:54 side by side a 68 reg strange looking machine with double front wheels, and a motorbike

DSC00500.JPG

Regards Neil

REgards Neil

white exec · Unread post by **white exec** » 18 Apr 2019, 09:35

No, no, Neil . . . Always entertaining!

Back with that 2-stroke article, if ever there was a need for a diagram, this was it.
Found this, which explains a lot:
Click on link to animate
https://cdn.instructables.com/FCP/APL1/ ... .LARGE.gif $\:D/$

Pug_XUD_KeenAmateur · 18 Apr 2019, 09:50

Even back in my school days the 2 Stroke was a rarity, Wartburg Knights and Saab 99's mostly.

Also remember seeing the Rootes TS3 in a 60's Commer Tractor unit at the Great Dorset back in 2013.
Quite a little curiosity.

One of these days I'll fix up my 2 Stroke Genny to run properly, suspect blocked Jets in the Carb; but for the moment its largely redundant anyway, having been bought primarily for cutting repair panels out of scrap 405's where no mains power is available.

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 10:31

NewcastleFalcon wrote: 18 Apr 2019, 07:58
And here's one from SAAB, niceish but well behind the most beautiful 2-stroke car ever made....which is

Anyone care to offer up any candidates! and off topic planes/trains/boats/submarines/hovercraft/model aeroplanes/standing engines......generators all welcome!

Regards Neil

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 14:28

Pug_XUD_KeenAmateur wrote: 18 Apr 2019, 09:50 One of these days I'll fix up my 2 Stroke Genny to run properly,

Have a pop over to the interesting/unusual engines thread Puxa......Toyota R&D working on a crankshaftless "2-stroke" genny as a "range extender".
link
viewtopic.php?f=2&t=61099&start=105#p606129

Regards Neil

white exec · Unread post by **white exec** » 18 Apr 2019, 16:54

Anything to keep the oil companies in the game! Toyota are fighting hard to prolong ICE product.

Joseph Swan . . . Now there's one for you, Neil.

Edison did his best to steal the limelight (no pun intended), as was his wont.

Gibbo2286 · Unread post by **Gibbo2286** » 18 Apr 2019, 17:39

One of my customers, a bike enthusiast, ran one of these as his favourite from his collection. He had a Mk 2 Jag but rarely used it

I wonder what happened to his collection when he died but I'd guess his son, who's mother described as a 'perpetual student' flogged them off.

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 18:52

white exec wrote: 18 Apr 2019, 16:54 Joseph Swan . . . Now there's one for you, Neil.

Did you forget to post the video up Chris? Newcastle Uni. Who knew?

Regards Neil

Unread post by **myglaren** » 18 Apr 2019, 19:04

First I have seen of it Neil.
Looks interesting,I may have the T-shirt but never attended Newcastle Uni other than for a graduation ceremony

NewcastleFalcon · Unread post by **NewcastleFalcon** » 18 Apr 2019, 20:42

myglaren wrote: 18 Apr 2019, 19:04 First I have seen of it Neil.

Yes my apologies Steve I mistakenly used your name when I was replying to a post by Chris...have since edited in Chris' name.

So with no contenders so far I will reveal the most beautiful 2-stroke car ever built

regards Neil

Unread post by **myglaren** » 18 Apr 2019, 20:58

I'm afraid I have to be a curmudgeon here and declare a long lasting dislike for two-strokes.
They sound awful and stink - much worse than the usual diesel pong.

On the other side I drove several SAAB 96s in Sweden and they are great from the inside

Loved the free-wheel, insane

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Two Stroke Spotting-Cars (and the odd bike)

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