Lighting SVEA 123r (without starting a wildfire)

I have a SVEA 123r that I purchased, new, 25+ years ago. Used it alot. A few years ago, I rebuilt it - no real reason as to why - just thought it was time. Purchased the kit from....Katadyne(?) and also put a new wick in. Stove performs a little better, but was fine before as well.
The one issue I've *always* had with it - even pre-rebuild - is during initial lighting, enough fuel comes out that it turns into a Moldoff Cocktail for about 30 seconds or so before settling down and hissing nicely. I've seen this whether I pressurize with fuel in the cup or use the pump. I'm guessing that the tank is getting overpressurized. I've watched lots of videos on it, but haven't been able to completely solve the problem. Any ideas? (FWIW, I love the stove and don't want to purchase anything else. Just sayin')

Thanks

 

Preheat longer. Try a wick in the priming dish.
Open valve slower.

 

Welcome to CCS

 

Sounds like you are opening the valve too much after or during preheat. Wait for preheat fuel to almost burn off before opening valve, not too much or it will do what you say. Light out of wind and be sure burner head (bell) is screwed onto the burner.
Duane

 

Having owned the 123 and 123R this appears to be a “feature” generally of the 123R as the spindle assembly or the needle & seat specifically, the mating surfaces simply lack the precision of the 123, it is very noticeable. It may be due to production tolerances some stoves would be worse than others. The “self cleaning” feature is a bit of kluge, it also destroyed any effective flame control. They have 2 settings compared to the 123 - high, and sorta kinda low.

You could try inspecting the needle and seat surfaces and dressing for a gas proof seal. The taper isn’t quite right. Or chuck it on eBay and get a 123

 

How much of a fireball are we talking?

Assuming you have a fully functional burner:
When bleeding preheating fuel from the nipple you get an inevitable bit of fireball. The fuel sitting above the valve will spurt out when the burner heats up.
To avoid this, don't bleed from the nipple. Instead use a second fuel like alcohol for preheating, or transfer some fuel with an eye dropper pipette from the tank to the preheat cup.

The internal cavities otherwise containing "fireball fuel" will be dry and preheat calmer.

 

I’ve not found that to be the case and experience as much facility to control the flame from as low to as high a setting on an ‘R’ as a 123. The wrong pricker rack setting could explain both symptoms.

 

My experience as well.

 

These are as simple as it gets.

i know exactly the symptoms he describes. If the pricker is out of rack alignment, it will be really bad. This was my first inclination, too - but as he explains it, this is a problem encountered prior to any disassembly and reassembly. It may yet be the case, but he would also likely have noted raw fuel leakage when stove is shut down, as well as difficulty when turning the valve shut.

This mechanism is as simple as it gets. It can’t be anything other than a bit of raw fuel spitting past the needle & seat during preheat at an excessive rate, thus causing the flames rising. You can hear it as well as see it. I thought this was “normal” as well, till I used the 123. There is no leakage past the needle and seat during preheat whatsoever.

As far as flame control, it isn’t even close. I would say the quality and usability of the stove took a bit of a nosedive when Optimus took over. I use these stoves a lot, if someone actually wants to use them as designed the 123 is a lot better, and it won’t scare the womenfolk and horses. As much.

 

I own a couple of 123's, an Optimus 80, and an 8r. I always squirt denatured alcohol into the priming pan, wait till all priming fuel is burned then slowly open the fuel valve. I never put a match to the burner until I hear the hiss of vaporized fuel. I must confess I don't have any experience with the 123r however. Jim

 

8R is the same principle, as a 123R, we are discussing.

 

One of the 123 family I have is a well used R given to me, no issues, maybe the newer versions are unable to be regulated very well, or issues with the pricker mech. Part of our fun is a flare up now and then on whatever.
Duane

 

Rereading this.
What parts did you replace?

Also curious about the wick placement.

 

Hey Everyone -

Thought I'd get an email every time there was a reply to my post, so haven't checked this in a few weeks.... To answer everyones' questions:

When I rebuilt it, two or three years ago, I purchased the kit from Katadyn.....this one looks like it: Svea Spare Parts Kit

For the wick replacement; I used a 100% cotton mop strands. I cut it and bound it to match the original. (FWIW, I believe the original was probably just fine....everything I've read says as long as you keep fuel in the tank; they're keep just fine.) After the rebuild the only thing I've really noticed is a little less yellow on the flame tips.

The rebuild instructions were compiled from threads on this forum. I seem to recall a procedure for setting the needle valve that I had to follow.....

The stove is used for backpacking and also for car camping. Its well-used. I do have a priming pump and associated fuel tank cap, for it, which I haven't used in years.

For priming, I generally use a needle dropper to put a little fuel in the priming cup. Just from what everyone is saying; **it sounds** as if - when I 'crack' the valve open; I get a bit more fuel spurting out then is desired.... Is that what I'm hearing?

I do recall one or two light offs that were more reasonable. Seems like I may have not used any preheat fuel and just warmed the tank with my hands.

The other thing that complicated all of this was the fuel key....its pretty soft with blades bent out of shape to where it wouldn't reliably turn the fuel valve. I've since replaced it with a clock key.

I've used it a few times since the rebuild. Once lit, it functions just fine. I can even turn down the flame somewhat.

 

Reading your first post "enough fuel comes out that it turns into a Moldoff Cocktail". Assuming you are not opening key too early or at all during pre-heat your spindle assembly is leaking and allowing raw fuel out during pre-heat. Rather simple tapered mating surfaces are used and can be damaged from over tightening or just worn from a lot of use. Could try to dress angle on spindle to reduce leakage. During normal preheat you may get a bit of a flair up when residual raw fuel in burner lights but no "Moldoff Cocktail" type flame. I fill the pre-heat reservoirs as full as I can to ensure proper pre-heat and this usually eliminates need for second per-heat which is a pain on Svea with its wind screen. The use of DNA will eliminate the soot you get using Coleman fuel for pre-heat. Enjoy your great little stove you dug out that has passed the test of time.

 

DNA = Denatured alcohol.
Duane

 

I think the biologists have already cornered that acronym...

 

I hope you’re not opening the fuel valve during the priming.

 

Why would he do that?

 

Just reiterating Daryl’s comment, “Assuming you are not opening key too early or at all during pre-heat….”