Why arm pump is stronger in right hand?

I got arm pump on left side cause I didn't use the clutch that much. Once I started using the clutch it got better.

You said brake is soft? Is there alot of pull? i.e. have to pull in front brake really far to get full stopping power? I personally have my brakes at instant engagement so there is very little movement but it seems to be enuff to prevent arm pump.

Whats your riding level? beginner, intermediate, pro?

do have ur hand twisted so the wrist and forearm are at an angle cause u could try to keep your hand and forarm at an almost striaght line... it could be that u hold on to the bar to hard

Not sure if I can give you exact positions for your hands but I'll try. I usually have my levers just below level so I don't have to reach for em. Some people like them turned down to keep them in an agressive stance.

With that being said, I keep my wrist and arm together most of the time. If I hit a section that requires a full throttle angle, I adjust and regrip. As soon as I'm out of the full throttle section I regrip again. If your constantly keeping your hand position ready for full throttle it gets tiring quickly.

Now for braking, I can't say I pay attention to that because i try to stand while braking as much as possible and only sit when I hit the corner then back up again. I have learned that if you concentrate on holding the bike with your knees you don't hold on as tight when accelerating and braking.

So, try and learn to regrip for certain situations so you are minimizing your motions i.e. not twisting more than needed. Less twisting keeps you in the correct position. and takes less effort.

Hope that helps?