I would like to purchase a seva 123 stove on ebay, rather than a 123R because if have heard that it gets hotter and is in general better than the newer 123R
However, I do not know the difference in appearance of the two stoves (I can only rely on sellers pictures)
Could somebody tell me the differce and perhaps give me a picture of each stove?

Thanks alot

I don't think ther's any way to tell the difference from a photo. If you see Optimus written on it anywhere than it's definethy an R.

Appart from that, i think they're identicle.

Ask the seller if it says optimus anywhere, and/or has it got a self jet cleaning device operated by the valve.

if the answer is yes, than it's a 123R

An old 123 is better because it simmers better. Some people clamin it's hotter, but i don't know.

I think the main difference between the 2 is that there is no regulator on the 123. Possibly there is some pressure loss through the regulation mechanism and therefore the 123 is hotter burning (this is just a guess)

I believe that the SVEA 123 is considered to be better made than the more modern Optimus 123R. You'll need to talk to someone who has several variatons they can compare.

Hi!
I got a 123R. But I cant remember I have seen a R of Optimus stamped on it.

The diference however is that the R model has the builtin cleaingneedle. The regulating screw therefore goes into the vaporisertube off center of the tube. On the original the reg. screw goeino the tube in the center of the tube. Making the old burner more elegant like the Primus no 71 burners. Check these two burners on ebay and you will have an idea what i mean.

Good luck!

The 123 has the control valve at a downward angle whereas the 123R is straight. I generally find the non-cleaning needle model(123)to run better.

Indeed Ross the simmering capability of the older 123 is much better. The control on the newer 123R's is limited on its travel distance by the geared tooth clearing needle assy., whereas on the older models the valve will turn several complete revolutions - resulting in as much finer simmer control. In real life terms I can perc a great pot of coffee, forget it on the newer 123R's - just too tricky to reduce the boil.
As for heat output it's probably very similar

Here is a visual comparison showing the 123 and the 123R side by side, with their brass windscreens removed. The 123 on the right can be identified by the downward-angled control key, as well as the open-ended spanner on the end of the key. The later 123R has a horizontal control key as you can see. I have found the earlier 123 to be more adjustable than the later 123R, and maybe a bit hotter (or is it just my imagination:)
Good luck with the Ebay hunt!

Then the question that comes to mind is: What if you removed the cleaning needle and rack, would that allow you to have finer control?

An interesting question - I've run them without the needle, but not without the rack. Might be worth a try, but I think I'd keep a wet towel available just in case.

Judging by the picture posted below, there seems to be a clear difference!

I've always assumed that the 123 runs better than the 123R because of "smoother" (more laminar) flow through its rack-less and needle-less tube. (Also less heat loss due to smaller surface area of the tube.) Taking the rack out leaves a lot of space to fill with fuel... It is an interesting bit of speculation, but I would keep that wet towel handy, and definately perform the experiment outside.
....Arch

For the most part the Svea 123 (old style) and the Optimus 80 seem to be very similar stoves. I think the 80 has a slightly larger fuel tank, but the burners, etc... seem the same. I swear my 80 burns hotter than my 123. Any ideas here?

You're correct Alan, the early 123 shares the same mechanical workings (burner stem, valve, burner) with the Optimus 80 (and Primus 71). There are some slight variances over the years, but they appear on both models (notice the ribbed section below the burner on the No 80). They both have the same fuel capacity, the 80 just has a taller, smaller diameter tank.
I too believe the 80 and old 123's burn hotter than the 'R' model...and I think Arch is on the right track with his 'increased laminar flow' proposal (above message), due to the straighter, smoother valve design. We need a real world test to see what the difference really is! (wet towels in hand)

I have a proper SVEA (the older one), and that has a ribbed section below the burner. Is the top off an Optimus 80 then?

...I've seen the 'ribbed' as well as the smooth burner stems on the 123, 80, and the 71, probably due to Optimus acquiring the Svea and Primus marks during various times.