as wangcc61 said run the copper one, earlier instructions said to remove the silver shim and thats what I did (though I got here in my notes its .2mm ?)

TOEBSTER2, D5 is shimmed for 30% nitro, you must do the above if running on 16%. Also my Sirio .12 trp pro (acc) had that same carb feeling when new. I think its when the needle is not perfect aligned, after some normal use it became smooth. Just went and checked a brand new Novarossi carb, its not silky smooth either though im sure with some use it would be

The sirio said hello to a fence so I got the D5, I have no negitive comments on this engine ATM It goes a lot better then the sirio ever did.