As people say, stick to what your local track racing options are. Balance how you can get the most racing. If the best racing close to you is Rotax, you might want to run that however. I’ve not seeing any Junior or Senior Roks locally. There is a robust Yamaha Senior field at Etown, so consider that too (Yamaha Junior is almost dead however).
– A used X30 can cost 2x or 3x what a used Leopard costs. If you’re not competing for the lead, the only reason to get an x30 is for the reduced theoretical rebuild frequency.
– With Rotax, you want the EVO kit on your engine, and that upgrade is no longer cheap. A Rotax (20-25 hours for top end) does not need as much rebuilding as a Leopard (6-10 hrs for cylinder, 15-20 hours for bottom end) or X30 (slightly less frequent than Leopard). For some reason, Rotax engines are not equal, and good engines can cost a lot of money too. Rotax also are requiring a newer cylinder next year at a national level, so an older Rotax engine, which will be fine in the local clubs, might get cheaper as a result.
– That being said, this season, we’ve witnessed quite a few stuck X30s, a couple of blown Rotaxes, and I don’t recall seeing any stuck Leopards, although I’m sure there must have been some.
We started this year, and got a Leopard, to race at Englishtown. The Leopard is also great for the Gearup Series. However, depending on the class, you might be able to run Rotax at Gearup, and most clubs will allow Rotax in TAG.
However, once we discovered OVRP, we realized that running a Leopard there meant running in a small mixed (Seniors and Juniors) Leopard class – in order to race in a decent field at OVRP, you need a Rotax, since they wont put the Leopard in with the Rotax racers. So we got Rotax equipment as well. There is no point racing at OVRP in a Leopard. So we now run both Rotax and Leopard in Juniors.
Re Leopard vs X30 – the local clubs make it possible to run Leopards in Juniors, since they allow a 28mm header on the Leopard vs 29mm on X30 – they are compatible and competitive, even though the engine characteristics are different. However, if the local club requires 25mm on the Leopard (per WKA rules), forget it – it will be 2 or more hp down on the X30 with 29mm header, and will never be competitive. Nationals will run WKA rules, eg Daytona Kartweek, so while it might allow a Leopard, it’ll be pointless. I’m shopping around for a cheap X30 as a result, just in case we want to run National events.
The Seniors at Etown do just fine with Leopards vs X30 – I suspect you will be able to compete fine with a Leopard. Their theoretical hp are similar. The track will make a difference – a lot of twisties should favor the X30, or Rotax, a long straight might favor the Leopard.
Re 30mm vs 32mm – especially at Millville, but also OVRP – you need to drive over the kerbs to be fast, so I think you need a 30mm, unless you are heavy. A 32mm will toss you up when you try to drive over the kerbs. At Etown, you can’t drive over the kerbs – many have turtles. And it’s a low grip track, so a 32mm might be better there.
Re Englishtown – even though its a parting lot, spinning out is not costly. You don’t really hit anything. The barriers do move. At Milleville, however, I have bent axles and lost chains from going off the track. Milleville is a nice track. But, my son’s favorite track is Etown.
We only go to Milleville for Gearup, NJSS, or NE Rotax, so I don’t really know what the local club options there are. Check out the number of drivers in each class using Race Monitor results.
In summary, get the engine that will give you the most racing with a minimum of 7 racers consistently at every event.