All 2st CR50 Swingarm

Hi there, just bought my 7 year old lad a CR50 and I'm looking to make it a bit calmer. i have fitted a 12" rear and 14" front so it suits his size too. Can anyone tell where to get the swingarm extend or buy replacement and also can you help with the clutch re making bike less agressive to start with! Don't want to frighten him before he gets going!

What wheels 14/12 did you take to yours cr 50