I’ve been struggling keeping the kart free during the last heat of the day on corner exit. About halfway through the final, the engine won’t pull out of the corners like it does all day long due to, what I’m assuming is the kart being stuck corner exit. I’m about 4 tenths off the leaders early in the day and no matter what I do, that gap usually grows to about 8 tenths from there.
I kind of think my kart is old and worn out causing me to be slow, but I’d like to keep that 4 tenth gap rather than let it grow. I only have one more race to figure it out before the seasons over and I look for a newer kart. I think it’s worn out because everytime I make a change, the kart will handle different but its more often than not neither faster nor slower. It’s easy to say its the driver but I’m able to keep pace and pass a few known good drivers early in the race, and they pass me back halfway through the race.
The kart generally handles pretty good besides feeling sluggish off some corners, usually any corner sharper than 100 degrees. In the second heat of the day I ended up going on two wheels in a corner which I’ve never had happen before. For the final I ran 1 lb less air pressure in the tires and widened the rear about 10mm total, reduced caster from full to neutral, and it handled great until the last half of the race when the track was at it’s stickiest.
So regardless what are some ways to keep the kart free off corner exit when the track is grippy? The only think I think I could have done is lower the rear ride height. Here is how it was setup.
Driver is 5’10" 196lbs
2016 or 2017 Top Kart Twister
LO206
Front ride height: stock according to Top Kart
Front track: pretty narrow, 5mm spacer on each side, kart seems to oversteer with it any wider, but I’ve only tested this when the track grip is low, so 5mm seemed to work best for me.
Front torsion bar in at soft setting
Caster: neutral
Camber: -3 degrees
Toe: 1.5 degree toe out
Neutral Ackerman
Seat: A few mm further back than what Top Kart recommends, if its any further forward, it looks like I’m leaning forward and I’m only 5’10".
Weight distribution is 39/61
Front of seat is even with bottom of the frame rails, rear of seat is about 8mm below the frame rails.
One seat strut on the left side
Rear ride height all the way raised (axle down, Top Kart’s recommended neutral starting point “good for 90% of the time”)
Medium Axle 1040mm
Rear track width: I’d start with the hubs all the way in in the morning and widen them out a little each heat. By the last heat they would be about 10mm out on each side
Tire: Hoosier R60b 7.1 rears
Wheel: Douglass low volume mag rears
Freeline fronts, not sure the size the stretch sidewalls out a little (all I can afford at the moment)
Im running 15 psi cold (14 psi on the right side) they end up about 17 psi hot. I’m at the minimum weight for senior with no lead, maybe 5lbs up front would help.
I’m not opposed to moving it up a bit, only that my driving posture looks goofy and the seat is swiss cheese already. Forgot to mention it is a flat bottom.
Besides that, should I have widened rear track more or would lowering rear ride height help?
Not a big deal I supposed, I’m about to give up on this kart and keep it for a spare.
Both of these are likely to exasperate the bind you’re experiencing because they will reduce load transfer…
But, you might be better off running close to max rear width anyway and tuning the front width to balance it. This will help with some of the hop you’re experiencing.
Seat stays and camber can have a big effect of how long the inside when stays unloaded, so you can also experiment with those.
I usually run positive 2.5 degrees camber just because I don’t know any better, which is 0 degrees sitting in the kart. The last race I went from positive 2.5 degrees in practice to -3 for the final heat, I was experimenting and had nothing to lose really. It wasn’t any faster or slower and it got tight 6 laps in.
As far as the seat position goes. Top kart recommends 625mm and I’m at 630mm, although my seat is mounted lower than what they recommend. I definitely don’t think I need any more mechanical jacking.
So general consensus is move the seat forward and possibly run lower pressures for the final?
Am I cynical in thinking that some chassis are just not as fast as others especially in 206? Especially older ones, mine was welded before I even bought it, now the rear bar going to the bumper is bent from a racing incident a few races ago lol. But I’ve been about 4 tenths off the leaders all year regardless.
You might know that already, but these seat measurement are only a very, very general starting point. More often that not, some deviation will be required.
Oh I forgot to mention, I’m not really experiencing a hop any more like I was previously, the kart lifts the tire how I think I want it to, sometimes it feels like its lifting too high but it stays up, until the end of the last heat and I’m stuck on corner exit.
Are you judging by lap times or looking at sectors too? I find laptimes can deceive me a little and sector analysis can give more details on if the change was a good way to go or not.
Gotta get the weight distribution in the ballpark before making any adjustments.
Seat placement and weight distribution is step one and the basis of all your tuning going forward. The kart will never react correctly to adjustments if the weight distribution is off.
I’ve got a 2009 Firstkart that I’m dying to put a 206 on. Maybe next season. The thing was amazing in Rotax in 2009 and it’s still super fast on practice days with an x30 or a Ka on it.
Right