Hi Jan, i’ve only have the cloth filter, ofcourse there are a water-“bubbler” after the filter, to collect condensate from cooler, this collects some of the worst soot if filter brokes during drive. Like a safety feature, when draining, and condensate are black, there is a leak in cloth.
As for cleaning, im very happy with this filter, have never cleaned the cloth, just emptying the soot collecting hopper in the bottom once a week.
This is calculated from a formula that Max Gasman posted long time ago, at old Swedish forum: GENGASDRIFT. Using the formula i came up with around 7m2 filter area for my engine, to be on the safe side i built it 13m2.
This formula was to calculate how much area needed for a filter to become self-cleaning.
I havent found the formula for now, but i will post it if i find it.
Yes! Please do.
S.U.
Do you possibly have a link to the welding cloths you used? What did you sew the cloths together with, or did you staple them together?
The welding blankets was the old type that Jula sold, white color, with eyelets along one side, dont know if they still have them.
Had to visit 3 different warehouses and bought everyone they got on the shelf, 
Eight ones if I remember correctly.
I sewed them together, had luck when asking at a upholsterer shop, she used to repair overalls for local firefighters, and gave me half a spool for free. 
Spun glass-fibre thread, resistant up to 1200°c
What do you think about this?
I saw in the new book that they had no more than between 4 and 7m3, even in large engines.
https://www.globaltools.se/maskiner/svetsutrustning/svetsskydd-och-svetshjalm/svetsfilt-550c-light-duty-af-obelagd-glasfiber-1-x-2-m-ljusbrun?gclid=EAIaIQobChMI5tba58jc9gIVIWAAAA7
Hi Jan, that looks much like the welding blankets i used, one of the reasons i bought mine at Jula warehouse was i could “inspect” them before i bought some. When pulling the fabric side-side and diagonally the mesh should not “open up” to much, and not be to tight either, if you pull it hard you should be able to se some daylight shining through, i even tested to breath through it, should go pretty easy.
Maybe you should buy one and do some testing before you buy more?
As for the surface area it should probably work with much smaller only thing is one may have to brush or blow the filter regularly.
I use a very big filter because i read alot about the builds in Finland, they had a calculation about when filters become self-cleaning (very low velocity per square) a big filter also becomes less sensitive to moisture and small amounts of tar, this seems to just stay in the soot-cake and fell off.
Edit: sorry, i have not found the “filter-formula” yet.
Yesterday i’ve had some time to spend on the moped build. Air/gas mixer prototype are in place, it’s a plastic tube (ptfe) inside the iron pipe, inner pipe is turning, controlled with throttle handle, the two holes lining up more or less.
Interesting to see if this will work.
There is also a butterfly valve to “choke” the air.
So the inner pipe works like how a round slide carburetor opens, except with rotation?
Haven’t really seen this round slide carbs, i got this idea from a very old chainsaw carb, but i suppose it’s like it, this inner pipe rotates, controlled by throttle handle, as i think of it now it maybe had been better to make it sliding?
Just think of them as a gate valve. Personally I think either way will work just fine. Round slide carbs are just a cheaper alternative to a flat slide carburetor.
Good point Cody. I think those sliding throttles were mainly used on English made bikes or at least that was my experience with them but I can see how a tubular throttle could be made to rotate in a home build WG carb to allow more precise control.
I have no experience with carburators but I would suggest two things. Stay with the rotating the sleave— make the hole in the sleave “egg shaped” instead of round. That way you will have more control of the air flow, a round hole will open fast and almost all at once. The other suggestion is–grind a ridge or ring around the plastic tube and put an “O” ring in to seal the air for more control. TomC
Hi Tom, i really like your suggestions, i already had o-ring’s, one between air and gas hole and one at the “open” end of the pipe, id just forgot to mention it.
As for the shape of the holes i think you’re totally right, they should be “drop” shaped for best control.
Im going to test and see with it this way, and improve it later on.
Mixer in place.
I mounted this luggage carrier to bring charcoal on, and attach gasifier to.
Feels like i building this backwards, should be the normal way to start with gasifier, and “build your way” to the engine?
Those are my thoughts exactly Goran.
Sorry guys for not commenting much, truth is l cant even read all the replys with you guys building and posting like mad 
but thats good.
Goran, l have found building it backwards works for me. Usualy when l build a gasifier l get all excited to try it out and take shortcuts with instalation. Wich can be equaly important as the gasifier it self!
Thanks Kristijan, that comment was what i was hoping for, it proofs i was thinking right about building this route, a nice flaring gasifier can get you so exited to test it out that everything else get neglected, semi-permanent solutions.
Trying this way because this is my first charcoal build (and two wheeled also)
Goran, what kind of a gasifier will you be building?
I have built a chargas moped before, great fun. A two stroker 50cc wich was not ideal thugh…
Two stroke, 50cc are the moped-“standard” (legal) here in Sweden, so i “cheat” a little with this 125cc four stroke, it’s a cheap engine.
As for the gasifier i havent decided fully yet, but it leans to something like the old Mako S, (charcoal downdraft with 4 nozzles placed like in an Imbert) i’ve also had thoughts about a downdraft with water-cooled central nozzle.
As you see i really need to over-complicate stuff
Filter going to be some type of sock, and a little cooler after it.
I wounder if you can find a large SS coffee type fine mesh filter . maybe they sell that mesh by the sheet ??? maybe not. Maybe that would be too fine for wood gas filter, Hope im not too far off coarse in my questains.
Seems like one of Matt’s sawdust filters made from a small fire extinguisher would be good. Now the mind of Mr Wacko takes over but if you were to lay that extinguisher inside a small ammo can filled with Ice you would have a very dense gas for that little engine. Now I’m going to have to make something like that and the list grows.