The short answer is yes. However, adding yk11 to your LGD shouldn't make the effects of LGD less pronounced. If anything, it should enhance it. Where did you order the yk11 from? There are a lot of fake SARMS floating around.
I really like the stack of LGD + Cardarine. Cardarine is probably the best supplement on the market today for increasing fat loss and endurance. LGD will cause a nice increase in strength while cardarine will greatly enhance endurance and fat loss. Cardarine (GW-501516) - the best GW-50 - Evolutionary.org
Sarms1.com carries a great product. Thats the source I recommend for SARMS.