Hi all, I was given an Optimus 8R which was in a very much used and abused condition. It had a couple of nasty dents in the tank and the case had been daubed with a dark blue ‘hammerite’ paint (which is not petrol resistant) - I stripped this off and gave the case a quick re-spray. Repainted case – not the original colour but the stove will be a ‘user’. However, the condition of the case was the least of the problems with the stove when I received it. For some reason the previous owner had decided to remove the vaporiser/valve assembly and, having struggled unsuccessfully to unscrew it, took a hacksaw to it! This is what the remains of the old vaporiser looks like !! How he removed the remaining threaded section from the tank I have no idea but, in doing so he must have partly destroyed the middle section of the female thread in the tank as, when he tried to fit the new vaporiser which he had bought, he destroyed the same section of the male thread on that. So, both parts were lacking the middle section of the thread and could not be screwed together. I had a rummage through my taps and dies and found a 1/8” BSP tap and die which looked like a close match to what threads remained and a trial on a piece of scrap bar showed that the die did indeed cut a tapered thread which matched the taper on the tap. Luckily, the die had enough depth to reach the remaining threads at the end of the vaporiser so the resulting threaded section would have a continuous taper along its length. I carefully re-cut the thread in the tank, going in with the tap only deep enough to produce a clean, continuous thread and re-cut the thread on the vaporiser. The two parts screwed together perfectly but, as the female thread diameter is now larger and the male thread diameter smaller than the original, the vaporiser now is slightly closer to the tank as can be seen in the photograph. The reassembled tank/vaporiser. With everything back together, I tentatively fired it up and was very pleased when it roared into life. No leaks - no explosions. The stove re-assembled and ready to go. Hard at work. Cherry red burner. This is the first 8R I have seen and I have a few questions that you may be able to help me with :- 1/ Even with the valve fully closed, a very small yellow flame appears at the burner jet during pre-heating which suggests an imperfect fit of the valve mating surfaces. Is this to be expected with a new valve? I thought this might be caused by an incorrectly set cleaning needle assembly but, having played around with the number of ‘clicks’, this does not seem to be the cause. 2/ When first lit the stove sounds like a V1 rocket but this tends to smooth out as the burner warms up – is this normal? 3/ There is a tendency to occasional, slight, flaring – the flame tips briefly turn yellow. This only happens very, very occasionally and does not appear to happen as often when there is a pot on the stove – again, is this normal? Dave.
Hi Dave a very nice stove and fettle there is a good chance that valve mating surface is not a perfect fit the inner mating surface may have a bit of wear the new spindle may bed in to fit pefectly all depends on how much wear carbon build up could prvent a good fit the second question itrs possible to sound like a V1 when first lit as the fuel may not be fully vapourised but all stoves sound and behave slightly different but once warmed up it sounds normal sounds ok to me there the third question could be a very slight enlargement of the jet or a bit of contaminent in the tank like moisture . what is a bit of a concern is the burner too close to the tank and causing it to over heat but if its only slightly it should be ok but best to keep a eye on it
Thanks, Brian. The vaporiser/valve assembly is a brand new unit (although the threads were mangled as described in my post) which the previous owner had bought to replace the one he had hacksawed off so both the valve face and the needle are new (as is the jet and cleaning needle) and, prior to me firing up the stove, have not previously seen service. Initially, I too was concerned by the fact that the burner is closer to the tank but this is only a matter of
Hi Dave even though you have set the needle to the right amount of clicks usualy 5 does it it may need 4 or visa versa even though i dont own a 8r at the moment all my 111s have worked pefect with 5 clicks you could try 1 extra or less and see how you get on. regarsing the tank i would think 1/4" is fine
Dave, you can take the cleaning needle out. The stove will work without it, this way you can see if it's the setting of the needle that's giving you the problem. Nice job with re cutting that tapered thread.
Gordon, I had been thinking of trying that. I have tried different settings of the cleaning needle between 2 clicks and 5 clicks with the same result but I will certainly give your suggestion a go - it should prove it one way or the other. Dave.
Oops !! Just checked and the tap and die I used was actually a 1/8" NTP (American Standard Taper Pipe Threads for General Use) and not BSP. I will amend my initial post. Dave.
Hmmm ..... maybe I won't as I cannot see an edit facility on that post! Is there a time limit for editing posts on these forums? Dave.
Thanks, HJ. Another question for anyone - will these stoves run on any other fuels other than unleaded or 'white gas'? Just interested. Dave.
Hi Dave, I would not use unleaded in any stove, these run fine on Aspen4 and Coleman fuel, and if need be also on panel wipe (it looks as pw has a higher boiling point, runs fine in my Coleman lantern & stoves, all are pressurised with a pump, but not so good in the Primus 71L and russian Tourist that have no pump. Burns rather yellow in the Borde) Regards, Wim
I wouldn't use unleaded in a stove -- even if the stove says you can do it. Unleaded automotive gasoline fouls stoves quickly. HJ
I understand the hazards of using an internal combustion engine fuel but I am quite happy to use unleaded in mine and this for two reasons - 1/ because I will only ever be using it in the open air, never in a confined space and 2/ I don't believe the tiny amount of fuel I will be using poses a significant risk. When you consider the amount of petrol consumed by vehicles, and the subsequent volume of exhaust toxins that you encounter walking down the street in any town or city nowadays, the tiny amount (mostly blown away on the wind in my case) generated by the five to fifteen minutes use of a small stove becomes virtually insignificant ... IMO !! Anyway, back to my 8R and a final question (possibly ). Having had a good play with it over the week-end, I have noticed that when turned down to a very low simmer the flames are very yellow. I assume this is because the vapour velocity at the jet drops to a point where it is too low to suck in sufficient oxygen to maintain a correct fuel air mixture. Is this typical of the 8R when operated at low fuel flows? Dave.
Great work on this stove. I often read statements like this on this site and also in stove intructions but in my experience it is not true. Back when I had only one stove, coleman apex 11, I used it for years on unleaded petrol. In fact when I went on a year long overseas cragging and hitch hiking trip I used it 2-3 times a day for about 7 months and it never had a problem. True most of that was in Australia and Europe with good quality petrol but I also used it in the Philippines, Romania, Bulgaria, Morocco and a few other places where I can only guess, and apologise if I am wrong, that the fuel quality may be lower. I don't use unleaded petrol any more but only for health and safety reasons, I have no concerns about petrols effect on the stoves. The only exception to that is the new stoves coming out of Asia (and the go-sytem flexi-fuel) that have those mico filters in the jets. You can clog those up just by looking at them. I am not saying that people should use petrol in stoves. I think petrol should be avoided. (I actually think anything but meths and kero should be avoided but thats just me. I just don't think I will really hurt the stove much. Dan
It is not pretty to look at, and sorry if this is taking this thread of track, but behold the glory of a stove that has never tasted coleman fuel... No flame shot as the pump is cracked. This is my favourite stove, the stories it could tell!
Just to wrap up this thread ...... After finishing the repair/refurbish - I replaced the pip in the pressure relief valve and polished the heat shield - I did a 'tea test'. The test conditions were - Two brimful mugs (20Fl. oz. = 568ml) of cold water (12.5*c). Dome style stainless steel whistling kettle (whistle on) having a base dia. of 8". Test conducted outside in mildly breezy conditions without any additional wind shielding. (altitude of site approx. 1,000Ft. ASL) The 8R was primed with meths and allowed 30 seconds warm up before the kettle was put on. Fuel was unleaded petrol. Result - Full whistling boil in 4 minutes 20 seconds. I think that is bloody impressive for such a small stove, what say you. Dave.
