Hey y’all! Am new to the forum(and frankly, to the sport), so I hope I don’t come across as being too ignorant about certain things here and there. Have been karting on and off for a year now, screwing around with a bunch of stuff, from Honda 270cc rentals, till ROKs or Rotax Jnr race karts just for fun. Each of them had their own challenges, and honestly have been enjoying my time at the wheel more often than not. But I digress.
I am aware that most of karting is typically split into race karts and rentals that use 2 strokes and 4 strokes respectively, which from what I understand has a general trend for things like power curves, to how the engine responds to certain throttle inputs. There are always going to be exceptions, and what I am curious about are how these exceptions stack against each other, being a 4 stroke race kart and 2 stroke rental (the former consisting of stuff like Tillotson T4s and LO206, the latter like DMAX). There are definitely going to be certain difference in terms of aspects such as the cost of ownership of such a 4 stroke Vs renting a 2 stroke, etc, but I am more interested in how exactly they differ in approach at the wheel. I don’t expect it to be the same at least, but any sort of insight would be much appreciated.
Anyways, I hope to get to learn more about the sport with y’all, and that I’ll make some friends along the way
4 strokes has usually less power and harder tyres (Intentionally excluding SA250 engine). Because of this, the package is a lot more forgiving and allows for more ways to be fast on the track.
That means you are not forced to trail brake or tone down the oversteer, as long as you have 100% of grip when going back on the power.
Because of the harder tyres, the falloff of the grip curve beyond the limit is not as punishing.
You also get a lot of torque at the bottom end of the powerband, which helps a lot the beginners
2 strokes
Well, softer tyres, less torque, higher peak power due to higher revs
That means you have to be a lot cleaner at all points of a corner. Trailbraking is mandatory, early throttle as well.
Throttle management is key to make the best use of the engine power, especially in Rotax/OK/Rok engines. X30 is a bit more forgiving.
I’ve driven the DMAX at Sandown. While it’s a 2-stroke, it is noticeably slower than a Rotax/X30/etc – perhaps 20hp vs. 30hp. And it didn’t feel geared optimally, which also made it feel underpowered coming out of corners. Finally, you’ve got an extra 100lbs or so compared to an owner kart as well as hard rental tires. So there’s a significant gap from a DMAX 2-stroke rental to a proper 2-stroke race kart.
I’d guess a T4 race kart would beat the DMAX lap time.
So the general gist is that a 2 stroke would likely need more careful throttle management because of the narrower powerband(being more focused to higher RPMs), while in the case of a 4 stroke race kart, due to the softer compounds, keeping the tyres at their limit without overdriving/overheating would be needed to ensure lap times, especially over a longer period of time?
That’s good to know, thanks y’all. Have only had a few runs in a Tillotson, but not something like a DMAX, so I had no idea how they’d stack. Appreciate the replies @tankyx@gxbry!
So there are also Electric rentals at K1 Speed and others. A lot heavier but alot more torque and a lot quicker than gas rental karts. There is also Blue Shock Racing Electric Kart Series with full on Race Karts as fast as gas Race karts.. Also K1 Speed has electric full race rental karts in California..
Just switched over from ROK GP (Rotax SR Before that) to LO206… Throttle management and using throttle to steer/balance the Kart is skill you’ll need in the 2 Stroke. At high end of the rev band, engine is responsive enough to change cart attitude. In the LO206, its more about not lifting and if you do, getting back on it as quickly as possible. Throttle response is dull, no real impact on kart attitude. There is no use of throttle to balance the kart when cornering.
That’s why I like Tillotson T4s more H.P. 15 H.P. compared to L206 9 H.P. Tillotson has more than L206 which has no torque too small displacement in my opinion for Karting. Wish Briggs and other Engine manufacturers would come up with bigger H. P. motors be more like the karts in the 70s. Like the twin 2 cycle motors. I use to run. And the 20 H.P. Deco Grand 4 Cycle Sprint Motors..
Higher HP four strokes exist, they just never really took off the way the lower power ones have. This is an older topic, but it covers some of the four stroke options up to 28HP.
