Martyn said: Thing is John, I've tried 2 different jets and I get the same forward bias off both of them. Fair point Martyn. I hadn't realised you'd got the same effect with both. If you could post some photos of the burner we could discuss whether that tilt of the burner mixing chamber is severe enough to make a difference. Burner tubes are quite bendable, up to a point, and realignement is usually easy enough, especially for someone with fettling skills like it sounds you have. Go easy though, the No.12 burners don't seem so robust as the Swedish (Primus, Optimus etc.) types, though on this one I had it was the fuel pipe that had gone Busted No.12 burner Others have been known to spring a leak at a burner tube joint. John
Hi Martyn, I look forward to seeing the result of a run of your No.12 with the cleaning needle removed. Your runs with 2 different jets were carried out with the cleaning needle in place weren't they? Remember that with all experiments it is a good idea not to change too many variables at once! Best Regards, Kerophile.
This is the latest video.... Original jet, lapped to remove any burr, reinstalled with original pricker, needle now straightened... [media=youtube]YfrmU8gMEZU[/media] (sudden changes in volume are because I had my finger over the mic ) I'm stumped!
Interesting vid Martyn, because comparing it with the other one you posted on Youtube there's been a shift in the arc of the flame showing reduced output. I wonder if that's due to the same jet nipple being tightened down in between test firings. I know what you've said about two jet nipples producing the same effect but it does suggest the problem's with the jet nevertheless. I'd be inclined to remove the burner, extract the jet, pricker rack, control spindle and give it a good blast through with compressed air. John
Martyn, can you meassure and compare the distance from the burner plate to the outer wall? And another one tot try, loose a little pressure when it's running, and see how the flame pattern change. I did with mine, also without the cleaning needle, and it was a lot better, maybe i pressured it to much (if that's possible).
I agree with Presscall. I think you need to try a new nipple/jet before you do anything else. Get a new jet or is there anyone near you who has got a similar stove? if so arrange to swap jets to test the theory. Steve.
Well spotted. Yes it does look that way doesnt it? I hadnt noticed but looking at the vid again, I'd agree. That means the problem must be down to the jet. I'll try and get a replacement.
Go easy with the pump on these as the little silver 'locking hoop' which locks the pump plunger in the down position is only soldered in place and can easily be knocked off.
Trojandog, will do - thanks for the tip. I've been looking at new jets for the No12 and I see some have fitted the 111/123R jet, which I think is designated the "M" jet (#2509). I think that jet is supposed to be 0.32mm dia. The thing is, when I tried the jet from a brand new 123R, the pricker needle from the No12 was too big for the hole and bent over in the cone on the underside of the jet (I should have tested it before fitting to the stove but hey ho). Today I grabbed an old 123R and tried the needle through it. It was a tight fit, but it did pass though with a squeeze. However, the needle passes very easily through the genuine No12 jet. This makes me thing that the genuine No12 jet is bigger than 0.32mm. I'm wondering if I should go for jet #2510, which is 0.37mm and designated a petrol jet. Will this work, or should I stick with the M jet?
Martyn, I've had a re-think and another look at your Youtube clips. Evidently you've had the Svea 123R jet and the No.12 jet installed and get the same effect of a lop-sided flame pattern, so your comment about it ruling out a jet problem is reasonable. Check the seating of the jet in the burner orifice. A nick in the rim of the jet orifice on the burner could be creating a fuel leak at the jet and the small flame that would produce down at the jet/burner joint would disrupt the main flame pattern - something I've seen happen on a number of stoves. Tightening the jet a bit more short of stripping the threads always does the trick once I've ruled out any obvious damage to the burner jet seating. It would explain why a change of jet doesn't improve matters and could still result in the radial shift of the those Youtube vids because of the variation in the mating of jet/burner between one jet and the other. Look for a small flame erupting from the joint when the stove's fired up. That'll confirm if that's the problem. If there is a fuel leak there, dress the jet seat and try tightening the jet a little more - easy does it though to avoid stripping the threads. John
Thanks for the suggestion, I'll check it out. Bit of a development today. I took the jet off again and gave it another lap with W&D. Then I sharpened a few matchsticks to a fine point and used them to polish out the inside of the jet. I figured a bit of matchstick wouldn't harm the inside of the jet, but might move a micro-burr or move a bit of crud. I fired the stove up again and the area of poor flame had much reduced. I ran out of paraffin at that point, so didnt get chance to video it. It might be a combination of things, but it looks like a bad or cruddy jet might be the major culprit.
Sounds promising Martyn. I didn't offer a comment on your question about jet hole sizes, but if the pricker rack needle is a tight fit in the 123R jet I'd stick with the original jet, especially since it seems to be responding to treatment. John
OK latest development, I had a brainwave last night, I did the sharpened match trick again, but this time dipped the tip in flitz metal polish. The result is the flame pattern is almost a complete circle now, however, I now get a yellow flame about 4" long above the burner. It looks to me like it';s burning way too fuel rich, which I'm guessing means that my polishing of the jet hole, which seems to have almost sorted the flame pattern, has also opened up the jet too much.
