The slabs I told about are 53" at the widest and about 40" and the narrow spot by 6' long. (Red oak.) Cut just over 2" thick they are over 400 lbs and it is all I can do to just slide it off the log and rotate it on one corner and then the other corner to get it out of the way some. I think with 2 people, even those big slabs could be moved with a little elbow grease.
I can't see how you get anywhere close to 400 lbs for that size.
If its 53" at one end and 40: at the other that's an average of 46.5" wide
Volume is then 46.5"/12 x 6' x 2"/12 = 3.875 cuft
The density of green red oak is at most about 50 lbs/cuft.
So that makes it about 200 lbs
Even if it was lemon scented gum (density of 71.8 lb/cuft) it would still only weigh 279 lbs.
That was a couple of slabs ago. I've gotten a little deeper in that log since then. It's gotten MUCH wider too. It's right at the max of the mill but the deeper I get, the wider it gets at the small point. The one I did yesterday took a FULL 2 tanks of fuel. It was over 30 minutes of solid cutting"
It sounds like either the wood is dirty or the chain is not set up right?
With a freshly sharpened chain I get about 36 sqft of cut (eg 9 x 4 ft) with one tank of fuel on the 880 in wood that will be as hard or harder than than red oak.
If I do not have a freshly sharpened chain for every cut I will need 1.5 - 2 tanks to cut the same area. Cutting with a less than freshly sharpened chain also places a significantly greater load on the engine, I can see the temperature increase significantly 20 up to 40F over my usual milling temp