Brunton/Optimus Nova MSR frankenstove

Discussion in 'Fettling Forum' started by erice, Oct 12, 2024.

  1. erice New Zealand

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    hi all, recently bought a 2003? Brunton/Optimus Nova stove that came without the all-silver alloy pump.
    a.jpg

    as per reading in this forum, these early Novas need the all silver alloy pumps with the CEJN connector that mates up with the CEJN quick-connect on the end of the braided fuel-line.
    P1.JPG

    unfortunately these pumps are no longer available new and are pretty rare down here in the deep pacific
    pac.jpg

    so rather than wait a year? for a used pump to turn up locally or pay triple? what the burner cost for a used pump from overseas

    the decision was made to see what could be done today with spares parts on hand.....a similarly sized MSR Simmerlite fuel-line, which would connect to the many MSR pumps and bottle available
    1.jpg

    first up was dremelling off the brass crimp joining the simmerlite braided hose to the generator
    2.jpg 3.jpg 4.jpg 5.jpg
    the inner of MSR fuel line seems to be a very soft and flexible black NBR rubber

    the thicker alloy crimp holding the threaded brass end of the Optimus fuel-line needed a slightly different technique, groove with fibre-wheel, finish with diamond bit, and it was quickly off too
    6.jpg
    the inner of the Optimus fuel-line is a much stiffer clear plastic

    the brass fitting went into the softer rubber well
    7.jpg 7a.jpg

    then the MOST IMPORTANT part, how to safely attach and seal the join

    LEAKING PRESSURISED GASOLENE NEAR A STOVE MUST BE AVOIDED

    ideally a new crimp would be used, but a search showed this would be difficult, slow and expensive

    so as 'perfection is the enemy of good'

    decided to press-on with available parts

    as the rubber inner of the MSR is quite soft it was decided to repeat a repair technique that had worked for fixing split alloy tent pole ends, ie tightly binding with stainless lockwire and then encapsulating with epoxy, to cover the sharp cut end of the twisted lockwire from snagging things
    8.jpg
    9.jpg

    note, this technique would probably not have been sufficient to hold the brass end fitting in the much harder clear plastic inner of the Optimus fuel-line....however you can see the lockwire has successfully constricted the softer MSR black rubber over the brass barbs of the fitting end.

    once the epoxy was set the franken fuel-line was screwed to the Nova spindle and everything went outside in the large stainless dish for MSR pump and bottle connection and pressure testing........pumping up the bottle to see if any air or liquid escaped
     
    Last edited: Oct 12, 2024
  2. erice New Zealand

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    1st burn test was White Gasolene, Durapump, small new Sigg bottle
    WG 20241012_125348.jpg
    full flame looked good but simmer flame tended to chuff...

    next was unleaded, Durapump, big, old Sigg bottle, much the same flame characteristics
    UL2.jpg UL3.jpg

    next was the surprise

    kerosene, old yellow MSR pump, new optimus bottle

    priming took longer, but full power appeared much hotter AND lower power could be taken right down to a dirty candle flame with none of the chuffing seen with the gasolenes
    k1.jpg
    k2.jpg

    k3.jpg k6.jpg

    at all times a careful watch was kept on the new join as well as the bottle seals etc

    will have to do some more testing as well as keeping an eye on the new join but it seems the single jet on this Nova is optimized for heavier fuels like Kerosene and Diesel than lighter ones like gasolene

    as for the magnetic jet cleaner...i can't see why just shaking the stove wouldn't do the same thing and then i could leave the heavy tool behind
    for motorcycle touring as the bike tools should cover the sizes used
    jet.jpg

    all in all a successful day's fettling

    might be time to sell the slightly heavier dragonfly
     
  3. erice New Zealand

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    sorry mods, 'fettling' is probably the wrong forum, please feel free to move to appropriate 'frankies' forum
     
  4. hikerduane

    hikerduane Subscriber

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    Would a hose clamp work better, although the extra end would hang out? Nice work.
    Duane
     
  5. William Ritchie

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    Brass hose crimp ferrules are available in a small size IE 1/4 inch ID . That and a set of coaxial cable crimpers has tightened and replaced a few hose terminations on my MSR stoves . Looks Factory when completed . Just a thought .
     
  6. ROBBO55

    ROBBO55 Subscriber

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    Congratulations erice on a successful modification :thumbup:
     
  7. erice New Zealand

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    thanks guys, great ideas on the hose clamp and coaxial crimpers

    i may use them as a way to put an msr fuel-line and pump on to my orphan sigg firejet stove......after i over-pressured an old o-ring, resulting in a small fire that melted the pump and fuel-line...see "sigg fireball"

    Sigg Fireball


    meanwhile the nova isn't looking like it will replace the dragonfly as my motorcycle touring stove

    unfortunately it clogs pretty quickly on unleaded gasolene and doesn't burn particularly well on white spirits

    where it really shines is an alcohol start kerosene stove...and i don't see the need to carry 3 fuels when the DF allows me to get away with just 1

    the soto muka had a good couple of trips as a bike touring stove....before it started frequently clogging and needing o-ring replacements on the banjo bolt

     

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