On a simulator, they both seem ok.

In reality however, I am having hard time steering the plane doing the right harrier roll (rolling clockwise).

The plane is a Pilot yak 55 100cc with a dle111

Could this be related to the engine torque?

TIA

When rolling to the right you have a bit of torque counteraction, especially when slow/high-alpha.

Another thing you should note, is that learning the rolling harrier maneuver to one side is one thing. Learning it to the other side is another. You basically start over. You have to learn the timing both ways, and it is not easy. Takes years to get this maneuver down right (at least it did for me, no good sims back then)

Keep at it, it's a doozy but rewarding once you get it down!

Vic

What he said. The torque from the prop assists in left hand rolls, but slows down right hand rillers. Imagine you are actually making the prop spin faster in a right roll.

It's all in your thumbs and requires lots of practice. I learned how to roll right to start. Then rolling left was hard for me and still is. Going straight and turning is nothing but stick timing. You can theorize about the torque characteristics but all that can be compensated for with practice. I still struggle with left rollers.

I learned rolling to the right so left is hard for me. Its weird, all I could do when first learning to the right was roll in a circle and then I was able to start steering any way I wanted to and then I was able get it down to where I could go straight. Now I'm learning left and can only go straight but can't turn to save my life. I can also only do rolling loops and riffle's when rolling right. So I'm in the same boat but I'm sure it will come with more practice.