There's a beautiful demonstration of how various adjustment of the flame spreader can turn a yellow flame into fierce blue: https://classiccampstoves.com/posts/26645 Philipp: I've been declaring for a long time that my stove hobby is not about cooking. It is for the pleasure of taking a 70 year old crumpy brass "thing" and restoring it to be a perfect stove. Yonadav
More of an observation than a real fix. The (new)Chinese-made Svea 123R seem to be a source of many more problems than used genuine Svea 123 and 123R models. And the problems often seem to be jet related. So my recommendation is to keep an eye out for a real 123R missing some less-critical part (windscreen, key, or even burner plate), because these often go for much less, and using your new stove for parts.
Apologize for bothering the forum with my Optimus 123 R issue. Yesterday, I lit it again and bended the flame-plate even higher until it stood about 3 mm above the rim of the burner bell. The flame still was not perfectly blue. Furthermore, as a disadvantage connected to raising the flame plate, the flame became very "flat" and spread over a wide area. One would need quite a wide pot for not to waste too much heat. Maybe a silent-cap would be the solution ? Regards, Philipp
might end up worse. If its an oversize jet then the reduced vapour speed will be even worse on a silent cap. Better to replace the jet which will be cheaper than a cap. What fuel are you using?
Purified White gas as recommended. Works perfectly in all my other gasoline stoves. Well, I will look for a replacement jet and see if this helps to solve my problem. Regards, Philipp
Hi Pillepalle, in my earlier post I recommended raising the flame-plate to see if the flame became more blue, to confirm that mixture was fuel rich. Yours is very fuel rich if you had to raise the plate so high. At this height it is impractical so you should consider replacing the jet with a new one. Base Camp sells them: Part 2509 Jet for stoves 8R, 11, 111, 123R, 199, 5R Price: £ 4.50GBP Best Regards, Kerophile.
And on it goes again . After I was sent an Optimus 8R I made a comparison between these two stoves. I found out that the burner bell and the flame plate were not completely identical (will provide some pics soon). When I changed the burner bells incl. the flame plates the 8 R burned with reddish flame-tips and the 123 R burned with a nice blue flame. So the reason for my initial complaint is not connected to the jet, but to the configuration of the burner bell and/or flame plate. I will make a test with interchanged bell and flame plate in order to find out which part creates the fuzz, but already now I know that these slight differences between the burner parts are the reason for one burner to burn nicely blue and the other one to burn reddish. Regards, Philipp
Very interesting, Philipp, Can you add some photos? It might help us improve some burner bells. Yonadav
8) Hi Philipp, I made similar observations on several stoves. Despite the right jet-size and flame-plate-height I had slightly red flame tips. So I played around a little bit and found out, that it correlates with the glowing red burner-bell. When your stove is at working condition turn it of for a few seconds until there is no more glowing of the burner-bell left. Then light it up again and I'm sure you will see a nice blue flame. (correct jet-size provided) Of course this only last until the bell starts glowing again Greetings, Fenris
You are right, Fenris, I was too lazy to report this phenomenon which I observed as well, too. After turning out the stove for a moment and lighting it again, the flame is nice and blue, but turns to red again after a short while. BUT: both bells on both stoves glow red, but only one (the original one of the new 123 R) apparently disturbs the burning process. BUT WHY IS THIS SO???
Philipp A picture is worth a thousand words. Please show us both burners. I will then try to replicate the phenomenon on some of my stoves, to find an answer to your question. Yonadav
"BUT: both bells on both stoves glow red, but only one (the original one of the new 123 R) apparently disturbs the burning process." It may not be disturbing the burning process. Is there any evidence of soot or smoke? The color may be due some residual salt on the burner bell/flame plate. Or perhaps something about the composition of the bell or flame plate results in ionization of some contaminating sodium or such.
Here come some - unfortunately rather bad - pics: The burner bells in comparison: The one from my 8 R is a bit more bell-shaped, whereas the one from my 123 R is rather helmet-shaped. Also the slots differ slightly in form and location. The flame plate sits deeper in its bell in the 8-R burner, the flame plate of the 123 R has been raised by me slightly in the (ungrounded) hope to improve the flame pattern. Both stoves burning, lit at the same time - the 8 R to left, the 123 R to the right: It seems as if the 123 R burned more powerful (but since it is higher than the 8 R it is closer to the lens, hence the flame appears bigger). Again the 8 R: a nice blue flame: And the 123 R: powerful, but with way too much red and yellow: The difference in color might also be due diffenrences in materials as pointed out by itchy, but where should all that sodium come from ? "Aren't stoves frustrating?" Regards, Philipp
Hi Phillip, What happens when you put a pot on the 123R? Any difference to the flame then? I have a number of stoves that burn perfectly blue with no sooting when used (as they were meant to be) for cooking with a pot in place. However, remove the pot and then some yellowing to the flame tips is evident. Cheers, Graham.
Hi Philipp, Thanks for the photos. I will compare yours with some of my stoves. The yellow flame looks like burning with insufficient oxygen. It looks somewhat wider than the 8R flame. I do not think there's sodium or any other material causing the color. Some steps that are worth taking: 1. Cross the top plates between the burners. See if the problem stays with the bell or the plate. 2. Make the 123R plate a bit more concave. Place it on a hollow item of proper size, and carefully tap with the round end of a hammer. (I place the hammer on the plate, and tap it with another hammer.) 3. Unscrew the 123R bell 1 or 2 turns to raise it a bit more above the jet. Aren't stoves interesting? Yonadav BTW - look at my avatar. I was able to obtain a perfect blue flame using a brass coin (I made it concave) held in place with some wire, as temporary replacement for the flame plate. This is on a Radius 42.
Good Morning, Philipp, and All, Hummmm.... Definitely a perplexing problem, and its solution seems to continue to elude you. Hard for the rest of us to say, for sure, as your stove is not "here", in each of our hands, to inspect and test ourselves. Looking at your two bells, the one from the 8R looks like a very proper Swedish burner bell, whilst the one for the Chinese-made 123 looks totally odd to me, without the proper "belling" at the top, and strangely shaped and located air vents in the side. To my eyes, your 123 bell looks far too "straight-sided" to work as it should. Of course, I could be absolutely wrong, as I seem to recall you've done a bit of parts swapping between these two stoves. Did your 123 bell fit and work on your 8r, and allow for a proper burn? If not, then I'd buy a new bell and flame plate from Basecamp, making sure they are NOS, and not of Chinese manufacture, and I'd bet that will cure your illusive problem. Just my two cents, and as written, I could definitely be off base. Good luck, and at least for me, I'd suggest sticking to the old, used, or NOS Swedish parts and stoves, if possible, as the Chinese ones most definitely seem to cause more trouble than they should, and on a regular basis. Take care, and God Bless! Every Good Wish, Doc
Pillepalle said, Then Yonadav said, There's the reason, Yonadav. Pillepalle had already said, That experiment tells me there's no issue about contaminants in the 123R's fuel tank (or the fuel) and that it's a fuel/air mixture issue as most have said. Primus introduced some No.71's with a variable air aperture in the burner bell to adjust fuel/air mixture. An unnecessary refinement in the Primus and most No.71's don't have it but it shows that the burner bell isn't just a shapely support for the burner plate, but a fuel/air mixing chamber too and that altering the air aperture size can influence the fuel mixture. I've done a lot of experimentation installing larger jets in butane stoves to get more power and opening up the air aperture holes to get the mixture right - otherwise yellow flames (or at best yellow tipped flames) result. Applying that principle to this 123R, I would expect that enlarging the air apertures in the burner bell would bring about the right fuel/air mixture and proper combustion with a wholly blue flame. Manufacturing fault - but surely there'd be more users who'd bought the same stove complaining of those symptoms? Could be a 'rogue' burner bell that got into the parts bin with more machining to be done? John
My opinion, too. So think I as well. Somewhen in the past I asked if it made sense to drill more holes in the burner bell, but was suggested not to do so. Now I am considering to grab a file and open up the air holes in the burner bell a tiny bit. When usind the forum search I found some other posts dealing with this problem with this stove, so I am not alone. Before I start filing I will make a test with only the flame plates swapped between the two stoves which hopefully will show whether the bell or the plate is to blame. Regards, Philipp Aren't stoves complicated?
I did a lot of experimenting with my different 123s when making a couple of home constructed burner plates. What impressed me was that a tiny amount of adjustment (less than 1mm) would significantly affect the burning characteristics. I eventually hit upon the "perfect" flame and was able to replicate it on all 4 of my 123s. It had 2 very distinct characteristics. The first is a slightly "ragged" blue section just as the flame comes out from underneath the burner plate, the second was that the burner plate didn't glow red, even after prolonged burning. I came to the conclusion that a red glowing burner plate indicated underburn. I may be wrong but I decided that the flame shouldn't be actually burning under the plate. Awaiting more experienced members opinion on this. Stan
I tend to view the burner bell on the Svea 123/Primus 71 style stoves as a replaceable part. They are fairly exposed when out of their cases and the thin metal makes them prone to damage. The thread size is pretty standard so they are an easy swap. I'm pretty sure that many of the bells that are on our stoves are not the originals. When spares suppliers state "for Svea 123" do they genuinely mean it is the the exact type or are they actually saying "will fit Svea 123"? I've just had a look at the bells on my Svea 123, Primus 71, Radius 42, Optimus 8R, Optimus 99, JS&S Lamb and was quite surprised at the variations. I wonder how many are original? I have 2 x Radius 42 and the bells are quite different. Although the main vents are similar in size, they are positioned slightly differently. Also, the bell on the left has a single small hole whilst the one on the right has four larger holes. The one on the right is from, I believe, the older stove and never runs as well as the other bell when I swap them over: Regards, Terry
