Another class option to look into is the rapidly growing DD2 (Direct Drive 2-speed) class. The engine is a Rotax DD2. What this motor is, is a high power version of the Rotax TaG engine with a 2 speed gear box added and also a direct drive system which uses no chain. They are competitive with the TaG 4-cycle engines, however the only on-track test against these karts was when the DD2s ran hard tires, they most likely will be quite a bit faster when on the same tire.
Rotax engine are the ONLY engine in karting that come with a warranty. The warranty is for one year.
These engines get very similar life to a TaG motor, which is 40-45 on a top end, 50-55 on a bottom.
No chain means a lot less maintenance. The biggest consumable on a kart is the chain, TaGs go through one every 3-4 days at the track, shifters every 5-6.
They run within 0.5-1 second of a stock moto shifter on the track, they are fast.
You have more options for racing around the country in a DD2 then you do in a stock moto, however both have more options than any normal karter will ever use.
In state they race in club, RMAX (Rotax Max Challenge), and CSC
They are a sealed engine package, only certified service centers around the country can work on the engines, this keeps competition very close as engines are all equal.
The class in Colorado is new to the CSC this year, so number of competitors is up in the air, however we have sold a good number of them this year.
Rotax parts are expensive, you have to replace them a lot less then other engines, but the parts are expensive when you do have to replace something.
They are a sealed engine package, some guys like to do the maintenance themselves.
Like Jeff said, call us at the shop with any questions.