Smoke out of chimney

I built a rocket mass heater using a metal jtube construction it draws great but im getting more smoke out of it then some people seem to be getting. Im wondering if its just because of its length or if i really need to be concerned with creosote build up. Its not complete and still very wet. I will link pics through imgur below. Any help or criticism  (because it's metal) will be appreciated

My rocket mass heater 2nd update https://imgur.com/gallery/Ik00S

From the pictures, more smoke is not surprising. The feed tube and at least part of the burn tunnel are bare metal, and will cool the fire significantly, preventing the extremely high temperatures that are part of the efficient complete combustion. What kind of insulation do you have on the heat riser?

Also, what size is your system? My impression is 6" diameter, but can't be sure. Do you have just one straight run of duct through the mass? If so, you are missing out on some heat capture, which doesn't affect combustion but does affect the amount of heat you get in the space. A 6" system is typically good for 30-35' of run, counting each 90 degree elbow as 5' (not including the transition from the barrel).

Once the core is properly insulated, you will likely see degradation over time, but you will get experience with use of it and be able to replace the metal parts with refractory at your leisure.

I used clay and perlite in the riser and its just the straight run of 15ish feet, its also only 5" pipe the jtube is 5" square stock (which actually turned out to be more money then the firebrick would of been) and before I found permies. I did understand that I would loose a bit of heat retained in the mass and it is still very wet and in MN atm very cold in the garage so may not even dry all the way this winter but between the blue flame propane heater and the rmh i can get it over 70 and the insulation I did this summer keeps it above 60 for hours after everything is shut off I also did the straight run for both space saving and I wanted the chimney at the back part of the roof, it's only a 2 and a 1/2 car garage and wanted a cheaper way to help heat it and plenty of junk pallets at work

Insulated heat riser was actually my first problem I didn't let it dry for more then a week and didn't realize perlite would expand that much. It completely chocked off the fire when it rose to the top of the barrel, but after cutting the excess off I haven't had one problem

5" is pretty small, so 15' is reasonable. It could probably handle 20-25' of straight run but not much more.

Your riser looks well insulated, so some cob around the exposed burn tunnel would be my main recommendation. If the cob is still drying, you are probably getting some extra cooling from that and lower performance... I expect it will dry out if you have regular fires in it and have the garage usually above freezing.