I started with a slightly used bike and proceeded to custom taylor it for my 71/2yo son.
Things I did: Soften the suspension by adding a Fastace shock with 550lbs/in spring. Up front I completely disassembled the forks that still had the original oil and very little of it. The internals were pretty warn so after a good cleaning I used the heaviest fork oil I could find 20wt. I also removed one of the springs and used a 1"preload spacer on the other. I replaced the bars with a more kid friendly bend Then topped it off with new levers and grips. New tires MX32 rear and MX52 front along with a new chain. I also replaced the flimsy stock foot pegs and mount (TRC pegs don't fit the SSR mount). This was all done after a cleaning, valve adjustment, spark plug, and oil change.