Hi Gail, I'm involved in a team and also some of the race organisation but I'll try and be unbiased as possible. Some of the others can correct any mistake / biases I put in:
Tracks: There's 3 tracks in KL - Shah Alam, Elite Speedway Plus and Sepang. Shah Alam is used mainly for fun kart events, the other two are certified for sanctioned events.
Series. There's 4 series worth knowing about:
my-Kart. This is an "amateur" group of enthusiastic drivers that organise events about once a month, normally using rental karts in Shah Alam. This is very much the best 1st step for a complete novice and a pretty good way to learn. They do allow kids to race but I'm not sure what the minimum age is. See
www.my-kart.org or their section in the forum.
Yamaha SL Cup. This series uses Yamaha KT100 SEC (electric start) engines. This year, the 5 race series was all at Sepang but there are plans to change it to more track in 2010. For this (and the other series below) you'll need to buy your own chassis (used = RM4000+, new = RM11,000 or so). New engines are RM6500, good used ones RM4000. The same engine is used in cadet, junior and senior with a very simple restrictor to change between them.
KKS Malaysian Championship. This was a 4 race series split between Elite and Sepang this year. For cadets, you can use the same chassis/engine as the SL Cup
Rotax Max Challenge. This uses Rotax Micro-Max engines for cadets. A new one will cost around RM10,000 with the special restrictor, exhaust and radiator needed for the Micro-Max class but the engine can later be used as a Junior when your son reaches 12/13. This is also a 5 race series and 4 of these races also form an "Asian" challenge. One round of the Asian challenge has been held in Indonesia but the announced plans for 2010 show only rounds in Malaysia.
In general terms, the best series for the younger and less experience kids is the SL Cup with the option of using the same equipment in KKS. For the 15/16 year old bracket, RMC offers a higher standard and challenge.
Of course, the cost of buying the karts is only the start of the expenses. For SL Cup/KKS, you need to budget between RM2500 and RM3500 per race for services, tyres etc. For RMC you need to budget more because it's a 3 day programme rather than the 2 days of the other 2 and the engines are more costly to maintain.
You probably need to get someone to store, maintain and run the kart for you. There's a number of teams/mechanics who will do this for you, all charging similar amounts although how it's packaged can be very different and some of the bigger teams are restrictive on what series they support.
I'm based at Elite SPC which is just off the Elite Highway leading to KLIA at USJ and there pretty much every day unless we're practicing/racing somewhere. If you want to meet up sometime, drop me a PM and I'll arrange a meeting with you