Recently I got an already polished Burmos 21, I think it was, or was destined to be an ornament. The 21 seems to be in good condition and doesn't appear to have seen much use, the flame spreader and uprights are especially clean. It's nice having no polishing to do for a change. The only thing that needed fixing with it was that the pump washer was dried up hard. I soaked it in kero for a week, it softened a bit but was too loose in the tube to make pressure. Being a bit of an O-ring convert I worked out that a 9/16" OD x 3/32" section O-ring was just right for the pump tube. On my trusty Unimat 3 lathe, I turned a brass piston to suit the O-ring, keeping the same outside diameter and bore of the original brass support piece (leather). The new piston is held on with the original nut with no modification required to the pump rod. This idea was copied from my Optimus 5/1 which uses an O-ring instead of a leather - must be a late model. I flushed out the tank and put the caps on the tank. I'm pleased to say that the pump valve is sound and holds pressure well, the washers on the caps aren't too bad either. The stove fired up easily and I put on the kettle - what a little beauty! I'm very pleased with it. Dave.
Hello, The stove looks nice but, what I am interested in is the fettle you did to fit the o-ring. Could you please post a photo of what the finished product looks like? Chuck
Gotta admit, I'm curious as well. Any one out there happen to have the piston/valve measurements for Opti 00s and primus 96? I like the idea of at least LESS kero spilling out via leather pumps.
If the one-way valve at the bottom of the pump tube is working properly you shouldn't get any kero leaking
I don't have a digital camera so I did two skeches and scanned and coloured them. The first sketch shows the original pump leather set-up. Light blue - pump shaft. Red - Brass support piece (leather). Brown - leather. Yellow - Nut. The second sketch shows the new O-ring piston set-up. The thickness of the brass piston is just about the same as that of the original Brass support piece (leather). Light blue - pump shaft. Red - Brass piston. Black - O-ring. Yellow - Nut. The sketches don't show the slack needed to allow the air in when the pump shaft is pulled. The pump tube's one-way valve is thankfully working fine. Dave.
