Wade, not sure where the carb regs are at today with the Rotax, but generally speaking it’s pretty much main jet and clip position that you’ll play with. There are various free “cheat sheets” and websites where you input weather conditions, etc. that you can use in order to get started with jetting, but ultimately, the best way is to get a weather station and do your own testing from there because every engine and carb WILL be a bit different.
All the engines have +’s and -‘s.
The good about Rotax:
- Very reliable engine
- It’s a sealed package, so theoretically all engines should be close, and it really comes down to driver, chassis and carb tuning
- It’s easy to be in the “ballpark” with jetting, which means you’re not likely to lean stick the thing
- Rotax isn’t trying to develop the “latest and greatest engine package” to beat the Max, so the engine isn’t going anywhere and the rules aren’t likely to change “too much” over time
The bad about Rotax:
- It’s a sealed engine package so you can’t do your own rebuilds (but seriously, this only affects a VERY SMALL number of people who would tackle this)
- It’s a sealed engine package, so you CAN CHOOSE to spend big money with the builder to have them pick and test for the “best” combo of sealed parts to gain an advantage (but again, anybody can test and match parts on any engine)
- It’s a sealed engine package, so if it is torn apart in tech, you have to pay someone to re-apply a seal (seriously, this might be the only thing about the Rotax that truly sucks compared to any other engine)
- It’s not always easy to maximize your jetting (ballpark is easy, but “dialed in” not so easy)
- Rotax does come out with updates every so often, and they’re generally not cheap (on the other hand, other engines tend to get replaced completely) – generally at the club level, you get a grace period to update to current specs, so this applies most at the higher levels
The other engines are good too. The biggest differences are that they’re not sealed packages (several advantages or disadvantages, depending on your point of view) and you might give up a little in reliability mostly because with a carb that can be tuned on the go, it’s easier to keep pushing the limits and work the engine harder. It can also be harder for an inexperienced driver to be in the “ballpark” on carb tuning. That said, it’s easier for an experienced driver to get “dialed in”. Just like the Rotax with it’s updates, the original Leopard is rarely seen anymore, as it’s MY09 Leopards, with talk that Parilla might be heading towards the X30 in the future. The original ROK was “upgraded” with the ROK TT. Etc.
Karting isn’t always cheap, but none of these engine packages have to be expensive to run.
Pick what has the best numbers and/or support locally and have fun.