Optimus 8

Discussion in 'Optimus No:8 (version prior to the 8R)' started by Jimg, Dec 30, 2025.

  1. Jimg Canada

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    Hey I am new to the group and have a couple questions. I have an Optimus 8 that was my father's. Just got it going but couple things...don't know if ime missing parts and the flame starts fluttering after it runs for a bit and " spits" fuel straight up in air?.

    I will attach photos and short video thank you

    20251230_164238.jpg 20251230_164228.jpg 20251230_164325.jpg 20251230_164242.jpg
     
    Last edited by a moderator: Dec 31, 2025
  2. hikerduane

    hikerduane Subscriber

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    Are you using kerosene instead of Coleman/campfuel?
    Duane
     
  3. Jimg Canada

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    Hey....

    Just bought a new can of camp fuel . Tank was dry and wick looked like it had not been used.
     
  4. snwcmpr

    snwcmpr SotM Winner Subscriber

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    How long was fuel in the tank before priming.
    How long was it run before it spit?
    How long has it run totally?

    Probably not relevant, but, are the seals, and pip, soft?
     
  5. Jimg Canada

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    Hello...

    Tank was dry, looked brand new don't know if father ever used it. I put new fuel in and perhaps minute or so later used hand warmth to prime.
    It ran for about a minute or so and then started to spit fuel ( burning) straight up.

    I ran it for about 5 minutes total.

    The seal on fuel tank cap looks and feels ok. I don't know what a pip is as I don't have any instruction booklet.

    Thank you
     
  6. hikerduane

    hikerduane Subscriber

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    What fuel did you use, not sure you did try gas? If stove got over pressurized, it would have possibly spewed fuel out of the SRV in the fuel cap where a pip is that makes a seal. I can’t see where the stove would have reached that point, but you never know. I think it is more likely that kerosene was used and the stove failed to vaporize it, resulting in raw fuel exiting once parts cooled after priming.
    Burner head (bell) screwed onto the burner snuggly? Stove needs thermal feedback to maintain fuel being vaporized.
    Many stoves listed for sale advertised as using kerosene when actually it is white gas sold as Coleman Fuel or camp fuel.
    Duane
     
  7. Jimg Canada

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    Duane

    I am using Coleman fuel..have not tried gas as of yet. The bell is on there very tight. Going to try again this afternoon and I will put the diffuser on top this time I did not when I initially tried it.

    Have a good video but can't upload....to big...

    Thanks

    Jim
     
  8. hikerduane

    hikerduane Subscriber

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    The flame plate is part of the stove, no wonder it did what it did. My reference to gas is not referring to auto gas but to Coleman Fuel, white gas, campfuel. The flame plate spreads the flame and directly provides thermal feedback to the rest of the burner. You need to turn raw fuel into a vapor.
    Duane
     
  9. snwcmpr

    snwcmpr SotM Winner Subscriber

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    I suspect that the wick ..
    Was not fully wetted. Try the stove again. It takes time for wick to absorb fuel.
    Or
    The wick was replaced by one not properly sized. Too small.
     
  10. hikerduane

    hikerduane Subscriber

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    If parts are not in place, also, a missing wick would allow a straight shot from the tank, with nothing slowing raw fuel down.
    Duane
     
  11. Jimg Canada

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    Duane

    Got it sorted out...works fine...burnt it first time without diffuser plate as I have no instruction manual as I mentioned before. The stove in general required cleaning which I did...just boiled a pot of water.

    Thanks

    Jim
     
  12. hikerduane

    hikerduane Subscriber

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    Very good.
    Duane
     
  13. Ed Winskill

    Ed Winskill United States Subscriber

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    That explains 'spitting fuel straight up', which I couldn't figure myself, because your photos show the flame plate in place.

    Just curious why you removed it. Anyway, good outcome!
     
  14. Jeopardy

    Jeopardy Subscriber

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    @Jimg The flame spreader plate is an essential part of the thermal feedback loop that maintains sufficient heat around the jet / control valve to vaporize the fuel so that it will burn efficiently.
    Even with it in place you might get a flare up when you open the valve, especially on a cold day. If that happens, close the valve, let the conflagration die out and do a second prime.
    Regards
    John
     
  15. Jimg Canada

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    Hey anybody know where I can get a repair kit for the Optimus 8...think I need new o rings and such

    Thanks

    Jim
     
  16. Tony Press

    Tony Press Japan Subscriber

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    @Jimg

    Try Fogas.se

    Cheers

    Tony