Yoder Smokers Community Forum

Hi all,
To start off… I am not complaining just bonding with my grill and thought you may be interested in some of my findings.
Here are some pictures I took of my ys640 with an infrared camera right after installing a new deflector plate with door. The images have a lot of information on the varying temps in the unit while operating at 300deg. The camera is an extremley accurate piece of test equipment used to trouble shooting all kinds of stuff, it can see the temp difference of studs in walls through drywall, jet engine accessory temperatures, HVAC etc...
Some of the really high temps in the pictures are being picked up from under the grate so not really accurate cooking temp. Interesting to see the deflector plate temp profile from the fans and the burn box. Also interesting to see how mid damper evens out the lower grate but throws off the upper (not a bad thing with thick point brisket).
The pictures are in sequential order for three damper positions: open, closed, mid. Shot: front, side, back... then door open: upper grate, lower grate.
The door was closed for 30 min between each series to let the unit settle in. I was finding it hard to figure out what was going on with some of the temperature differences so I put my aviation background to good use!

look at how even the lower and upper grates can be. Remember this is an empty grill so i think this is as bad as it gets. I have cooked bacon, cookies, potato wedges with little variation across the grates so I know the temperatures seem to even out with the cooker loaded up. The upper and lower grates seem to follow the probe results from yoder.

adjusted all the way out...

Adjusted all the way in...

Adjusted middle...

I haven't found a way to even out the left/right variance of both grates at the same time but I do most of the sensitive cooking on one or the other. This grill offers a lot of control for all the different things we do!



In conclusion, test seems to say ...
* deflector damper open for even upper grate temp (wings and things?)
* deflector damper mid position for even lower grate temp (butts bottom briskets top?)
* damper all the way in for grill grates?

Was running out of pellets so I stopped playing and started cooking:) Has anyone else found similar results?

Thanks for the awesome information. You should check this out:

To make a long story short, when I bought my first Yoder YS640, I spent a month "testing", with 12 probes in the cooker, 6 on top and 6 on the bottom. I was mapping the cooker in somewhat the same manner as you have. I burned through hundreds of pounds of pellets doing this testing.
My personal conclusion? It was a waste of my time and pellets. I should have been cooking and eating.

The sliding damper on the YS640 is pulled all the way out and back in just a few inches, and stays there. It hasn't moved from this placement since the beginning of 2012, and I fill the cooker, do smaller cooks and do grilling.

that's like having a double heat deflector! I wouldn't want to clean that every time...lol I did bacon the other day at 250...over all pretty even but matched what the images show.

Herb i know this may not be the right area to ask but it falls in the temp profile category.
I have a request for brisket and turkey! two completely different philosophy cooks. Was going to start the briskets (2@12 lbs) at 2am at 225 on the top rack, Then paper wrap after barked (6hrs or so) and continue for another 3-4 then crank it up to 325 put both turkeys on the lower racks and cook till done. brisket will hopefully be done before turkeys to rest...dinner at 5. any advice?

damper set for even bottom...

Your plan is sound, but you need to be flexible, as every piece of meat cooks differently, and the cook time is dependent on how you trim the meat. The minimum I rest brisket before slicing is 2 hours, but have held for up to 6 in a cambro. A rough estimate for turkey at that temperature is 20 minutes to the pound, but this depends on if the turkeys are whole, spatchcocked or parted out. When you are cooking at higher temperatures you must be more in tune with what is going on in the cooker, as meat can easily get overdone.

BTW - I believe they had the heat diffuser plate out of the cooker when they did the test with the flir in the video.

Thanks Herb! more questions

Does the 640 put out more smoke at lower temps or is that a myth? seems like it is always putting out nice blue smoke no matter what temp I set. have always been of the mindset "more smoke in meat came from longer time on the grill" which leads to the next question...
Have you ever done a low and slow turkey? I have always done them at 300 plus using other methods... my fear would be drying it out.

I know the 640 cooks from the bottom up but it also has some convection with the fans and all so more efficient?

Thanks again!

The smoke is the same across all temperatures. Yes, at lower temperatures, the meat does sit in the smoke longer. Personally, I have never seen this as a benefit, so I cook hotter, almost never below 250 degrees.

Yes, I have done poultry at 225. The skin is a throwaway cooking at that temp. Yes they turn out a little drier if you don't inject. With the higher temperatures I have found that I don't need to inject like I do at the lower temperatures.

There is air movement in the cooker, and there is a positive air pressure inside the chamber as well, but, the convection effect is minimal, as the air flow is directed specifically to push heat across the bottom of the diffuser plate and out the chimney. So there isn't any directed air "mixing" as with convection ovens.