Can't change the orientation of a welded part?

I've been trying for hours to rotate a part to 0,0,90, however it is welded to the humanoidrootpart, making it not rotate. I can't understand why, and how would i rotate it while it is welded? Code: (Although not all of it is needed)

game.Players.PlayerAdded:Connect(function(plr)

--Wait for the character
	repeat wait() until workspace:FindFirstChild(plr.Name)
	
	wait(1)
	
--Variables
	local char = plr.Character
	local rootpart = char:WaitForChild("HumanoidRootPart")
	local humanoid = char:WaitForChild("Humanoid")
	local HighTorso = char:WaitForChild("UpperTorso")
	local LowTorso = char:WaitForChild("LowerTorso")
--Code
	humanoid.WalkSpeed = 0
	char:MoveTo(workspace.SpawnLocation.Position + Vector3.new(0,3,0))
	
	rootpart.Orientation = Vector3.new(0,90,0)
	wait()
--Legs
	local RUPPERLEG = char:WaitForChild("RightUpperLeg")
	local RLOWERLEG = char:WaitForChild("RightLowerLeg")
	local RFOOT = char:WaitForChild("RightFoot")
	local LUPPERLEG = char:WaitForChild("LeftUpperLeg")
	local LLOWERLEG = char:WaitForChild("LeftLowerLeg")
	local LFOOT = char:WaitForChild("LeftFoot")
	
	RUPPERLEG.Transparency = 1
	RLOWERLEG.Transparency = 1
	RFOOT.Transparency = 1
	LUPPERLEG.Transparency = 1
	LLOWERLEG.Transparency = 1
	LFOOT.Transparency = 1
	
	rootpart.Anchored = true
	local pogo = script.Pogo:Clone()
	
	pogo.Anchored = true
	pogo.CanCollide = false
	pogo.Orientation = Vector3.new(0,0,90)
	pogo.Parent = char
	pogo.Position = rootpart.Position - Vector3.new(0,2.7,.3)
	
	wait(5)
	
	local weldPogoTorso = Instance.new("WeldConstraint", pogo)
	
	weldPogoTorso.Part0 = char.LowerTorso
	weldPogoTorso.Part1 = pogo
	
	rootpart.Anchored = false
	pogo.Anchored = false 
	humanoid.WalkSpeed = 16
end)

Yeah, that's what happen with weldconstraints. Try using Weld and setting their properties C0 and C1 (CFrame values).