I have a Primus No. 5 that doesn’t burn evenly. There is a consistent arc of about 120 degrees which burns orange every time I light it. I have tried the top caps on another stove without the same problem. I have cleaned and reseated the jet but the problem persists. Any tips on what to try next? -R
Hi @IRM your burner is receiving more fuel on one side. This results in a fuel-rich mixture and orange flame pattern on one side. There are a number of possible reasons for the uneven fuel feed, including: 1) It is possible that the jet aperture is partially blocked and feeds one direction more than the other. 2). You might have a hole/leak on one side the fuel feed tubes or dough-nut shaped vaporiser of the burner. This enriches the fuel feed on one side of the burner producing the resulting uneven flame pattern. Check and prick the jet. If that doesn’t work clean and inspect the burner vaporisation tubes and dough-nut for possible leaks. Tell us what you find. Best Regards, Kerophile.
Here’s what lunchtime produced: No sure what to make of the seam, I don’t see it on my other 2 silent burners. There’s a slight unevenness in the height of (what I’m assuming is) the vaporiser bowl: But the circumference is almost true, perhaps slightly off around 4 o’clock: (I’ve not had cause to bisect a line like that in a _long_ time) Enough for a prognosis? -R
Your stove was manufactured by AB Optimus (later 1960s-early 1970s), and the burner is therefore an Optimus no. 205 (though Primus Trading AB/Optimus sold them under the Primus name as no. 4138 for a few years). These burners featured a seam in the rising tube and holes in the tube below the inner hood, as well as three sets of three holes punched into the top of the inner hood. It is not the same burner as the older Primus no. 4138 (or 4139, with Primus metal outer hood). Make sure that your kerosene is first quality and that you have flushed out the tank thoroughly before attempting to light the stove. Sometimes these dirty orange flames can be eliminated in this way. In any case, I would check that before replacing the burner jet or taking more drastic action. Often owners, noting unclean flames, use the pricker to try to clear the jet, thereby enlarging the hole. Try to get your fuel and tank completely clean first, then see where you are at. Peter
Thanks to both of you. Replacing the jet did the trick - I was probably a bit overeager with the pricker when I first got the stove. Live and learn! Thanks also for the potted history Peter, the stove is a few years older than I thought. -R
Here it is… to be fair to the previous owner, it was in great condition, all I did was give it a clean, stuff up the jet and have to replace it… -R
Thanks for posting the images. You could try a bit more tank pressure. We like to see blue flamelets and outer caps heated clean. Best Regards, Kerophile.
