Full Kojin not boiling full Evernew 900ml

Myles21

Ultralighter
After using the Trail Designs Kojin with my Evernew wide 900ml / Sidewinder setup fairly extensively, I've found that it's fairly hit and miss as to whether the full stove will bring a full pot to boil. I've not really measured the quantities of alcohol I'm using, I just fill it up 'til it won't take any more - this has to be done slowly so the wadding can soak up the fuel without overflowing. The 900ml pot is my go-to for most day and overnight/multi-day trips, both solo and with my wife, so I often boil a full pot. Not sure why, but sometimes it'll boil on one fill of alcohol, other times it'll need refilling to complete the boil. I'm guessing that the kojin and similar stoves aren't really designed to bring that volume (750 - 800ml?) of water to a boil on just one fill. and that when people quote boil times for a particular quantity of alcohol they are generally referring to 500ml or less of water. Anyone else using this set up who can comment?
 

mjh

Backpacker
I use a speedster equivalent and 20-30ml of alcohol easily boils 650ml of water with fuel left.
Are you using it with a cone or decent windshield?
 

Mole

Thru Hiker
A full we have used that setup for some years now.

A full Kojin is c30 ml. We get a 750/800ml boil no problems.

Mostly I boil c650 ml of water for a brew as our mugs are 330ish. 20 ml approx fuel usually does it. ( I have a 75ml bottle I keep in the pot and get 3-4 brew boilss from it.
 

Myles21

Ultralighter
Just wondering if the wadding in my kojin has become a bit compressed. It’s certainly a bit grubby now. Yes, I use the Sidewinder cone and ti floor/heat reflector. Not quite sure why it doesn’t always boil the full pot, as sometimes needs refilling on a warm and windless day. I really like this setup as I can make a big drink and rehydrate a meal from one boil.
 

Whiteburn

Thru Hiker
I use the same setup with a MYO stove of similar size (volume) to the Kojin, 55 dia * 25 high with insufrax batting. I just filled an old stove (batting a bit sad) with 35ml no problem which is plenty for 1L, I normally only boil ~650ml (enough for 2 cups of tea) & I always have fuel left. It could be that the batting that TD uses is not as absorbent as the insufrax.
FYI, I haven't tested a Kojin but many other sizes of cosmetic pot type stoves & found the the efficient sweet spot (with 900ml Evernew & sidewinder) is a stove with a throat (internal neck) of ~47mm, the Kojin looks to be larger than this so it may not be the best in terms of fuel efficiency but it should be a faster boil.
 

Jon Fong

Trail Blazer
After using the Trail Designs Kojin with my Evernew wide 900ml / Sidewinder setup fairly extensively, I've found that it's fairly hit and miss as to whether the full stove will bring a full pot to boil. I've not really measured the quantities of alcohol I'm using, I just fill it up 'til it won't take any more - this has to be done slowly so the wadding can soak up the fuel without overflowing. The 900ml pot is my go-to for most day and overnight/multi-day trips, both solo and with my wife, so I often boil a full pot. Not sure why, but sometimes it'll boil on one fill of alcohol, other times it'll need refilling to complete the boil. I'm guessing that the kojin and similar stoves aren't really designed to bring that volume (750 - 800ml?) of water to a boil on just one fill. and that when people quote boil times for a particular quantity of alcohol they are generally referring to 500ml or less of water. Anyone else using this set up who can comment?
i pretty sure that I read somewhere on the Trail Design site that the Kojin was designed to boil 2 -3 cups of water. It was designed to be a more packable stove than the original 10-12 and to be used with the Sidewinder cones (600 & 900 ml pots).

From https://andrewskurka.com/preview-trail-designs-kojin-stove-russ-zandbergen/

The 12-10 will not go away. The 12-10 performs better with large 3- to 5-cup boils. The Kojin seems to have a sweet spot at about 2-cup boils. We will still recommend the 12-10 if the customers plans include boiling 4 cups of water at one time.
 

Robert P

Section Hiker
This is worth a look (Kojin etc with a cone):

The test used 2 cups of water (less than 600ml) - surprising to see how much fuel the Kojin used under some conditions. Looking at this you could see why it might be a bit hit and miss with a full 900ml pot
 

TinTin

Thru Hiker
After using the Trail Designs Kojin with my Evernew wide 900ml / Sidewinder setup fairly extensively, I've found that it's fairly hit and miss as to whether the full stove will bring a full pot to boil. I've not really measured the quantities of alcohol I'm using, I just fill it up 'til it won't take any more - this has to be done slowly so the wadding can soak up the fuel without overflowing. The 900ml pot is my go-to for most day and overnight/multi-day trips, both solo and with my wife, so I often boil a full pot. Not sure why, but sometimes it'll boil on one fill of alcohol, other times it'll need refilling to complete the boil. I'm guessing that the kojin and similar stoves aren't really designed to bring that volume (750 - 800ml?) of water to a boil on just one fill. and that when people quote boil times for a particular quantity of alcohol they are generally referring to 500ml or less of water. Anyone else using this set up who can comment?
Depends on starting temp of water and altitude
 

Myles21

Ultralighter
This is worth a look (Kojin etc with a cone):

The test used 2 cups of water (less than 600ml) - surprising to see how much fuel the Kojin used under some conditions. Looking at this you could see why it might be a bit hit and miss with a full 900ml pot
i pretty sure that I read somewhere on the Trail Design site that the Kojin was designed to boil 2 -3 cups of water. It was designed to be a more packable stove than the original 10-12 and to be used with the Sidewinder cones (600 & 900 ml pots).

From https://andrewskurka.com/preview-trail-designs-kojin-stove-russ-zandbergen/

Really interesting to read these. I just heard back from Rand at TD and he said pretty much the same, that the Kojin is really designed to bring 2 cups of water to a boil. I do have a couple of Starlite stoves and a 12-10 knocking about somewhere. May give them another go for larger boils.
 

Mole

Thru Hiker
Well, I'm surprised by the claims of only suitable for 2 cup (485ml) boils. That's not my experience.

To confirm, I just did a test with our Evernew 900/Sidewinder/well used Kojin.
I filled the Kojin,
Filled the pot to the lip the lid sits on.

Set it going outside. ( 35m a.s.l.)

Got a rolling boil 13'10" and it carried on burning n boiling away until 18mins 50sec.

You can see how full the pot is in this photo:

IMG20210925184953.jpg
 

Myles21

Ultralighter
Well, I'm surprised by the claims of only suitable for 2 cup (485ml) boils. That's not my experience.

To confirm, I just did a test with our Evernew 900/Sidewinder/well used Kojin.
I filled the Kojin,
Filled the pot to the lip the lid sits on.

Set it going outside. ( 35m a.s.l.)

Got a rolling boil 13'10" and it carried on burning n boiling away until 18mins 50sec.

You can see how full the pot is in this photo:

View attachment 35025
I know, it’s not my experience all of the time either, just that I can’t rely on it to come to a boil every time.
 

Paiolo

Backpacker
Perhaps the distance between the top of the stove and the bottom of the pot is not optimal?
Do you have a photo of your system at work?
 

Paiolo

Backpacker
Even if it is too far the efficiency can decrease. There is a precise range in the stove-pot distance to get the best performances/efficiency from the stove.
A second question is which type of alcohol are you using
 

Mole

Thru Hiker
🙄

It'll be exactly the same setup as mine if it's a TD cone/Kojin and Evernew 900.
Which works fine.

I suppose if the cone is on springy vegetation and the pot full, it will sit low, while stove sits higher than normal as it is light, then the flame gap will be reduced.
But a marginally reduced flame gap usually just means a longer boil time and sooting.


I'm guessing wind or possibly poor fuel may also be a factor
 

TinTin

Thru Hiker
I wonder if it isn't taking in 20-30ml for some reason. I measure my fuel in a 20ml syringe barrel and use my finger as a stop. 20ml in a small speedster with windshield/pot stand usually boils 600ml water to a rolling boil (not timed it but its not long enough to bore me). If it has been wet and windy an exposed water bottle can get to be a few degrees cooler than the ambient if it is exposed, like hanging on your shoulder straps for example.

I agree with @Mole (not something you say every day :cool: ) re poor fuel.
 

Myles21

Ultralighter
Yes, I think these must be a number of factors, like people are discussing above. I’ll try to be more observant of the conditions I’m using the stove in and will measure the quantities a bit more closely. I’m invariably using EcoFuel at the moment.
 

Myles21

Ultralighter
Left the lid off my Kojin overnight to make sure it was completely empty, then filled it with 30ml EcoFuel and set it going under the Evernew 900ml pot filled with 800ml cold water. I didn’t time it but it did reach a boil, just as the stove was sputtering and about to go out. There was a breeze which was blowing the flame about a bit, so I turned the cone so that the bottom vents were away from the wind. This could well be a reason for the success/failure of reaching a boil - the side of the cone opposite the joint doesn’t have vents along the bottom, so if this side faces the wind there is less disruption of the flame. If the joint/pan handle opening and bottom vents are facing the wind then this could well prevent a boil when it’s a bit breezy, even when the Kojin is filled to the brim.
Anyone else find EcoFuel pretty sooty?
 

Mole

Thru Hiker
Left the lid off my Kojin overnight to make sure it was completely empty, then filled it with 30ml EcoFuel and set it going under the Evernew 900ml pot filled with 800ml cold water. I didn’t time it but it did reach a boil, just as the stove was sputtering and about to go out. There was a breeze which was blowing the flame about a bit, so I turned the cone so that the bottom vents were away from the wind. This could well be a reason for the success/failure of reaching a boil - the side of the cone opposite the joint doesn’t have vents along the bottom, so if this side faces the wind there is less disruption of the flame. If the joint/pan handle opening and bottom vents are facing the wind then this could well prevent a boil when it’s a bit breezy, even when the Kojin is filled to the brim.
Anyone else find EcoFuel pretty sooty?
Yes. I do find it sooty with this setup.
 

mjh

Backpacker
If it is sooty then it sounds like something in your setup is stopping it from burning properly (soot is a sign of incomplete combustion).
Is enough oxygen getting to the burner or is the burner design the problem?
 
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