As I got it. Changed the filler cap washer and fired it up. Thinking of changing the filler cap to an original Optimus so I can use my mini-pump. Powerful little stove.
I don't know if they have changed since I bought my minipump in the 1970's but the cap is different from the normal cap that comes with Optimus. The nose around the safety release valve is much longer than the standard nose and it is cylindrical, not rectangular, hexagonal etc. Your minipump probably came with the appropriate cap, unless second hand or different model stove. Good Luck, Jim Henderson
Hi guys. It is different, I know. Here is a shot of the stansport cap next to my Optimus 199.  Totallydifferent as you mentioned. But the thread size is the same, so I will try to get hold of one more Optimus cap to use on the Stansport. The kettle is a Norwegian made and from the 60s. The brand is Il-o-van, meaning ild og vann (fire and water)
I had one of them. Here I compare it to a 99. https://classiccampstoves.com/threads/optimus-99-and-taiwanese-clone-comparison.30175/
Nice comparison, Billyboy. I notice two things different between yours and mine. The "made in Taiwan"-stamp is underneath on mine, and the pot support on mine is steel, not aluminum. Without the use of my mini-pump it was a bit slow. But when I gave it a few strokes it produced good heat.
