I imagine installing seat struts would also accomplish this, seeing as there are none on the kart pictured.
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@beherr3 I will ask him how the “Eurolean” affects the kart. It is something he does quite a bit of in certain corners.
@ChrisHoran He has a pretty negative relationship with seat struts. When we start hopping it can get pretty tough to drive and painful, even with the Bengio. We run them in low grip conditions sometimes, but haven’t had much success in the heat at NTK with them. It seems to lift more and release the outside tire and the slam even harder.
I think if I take out even more caster and narrow the front it may be viable to put em back. Right now he is at neutral bottom pill and is forward 1 position on the top sniper pill. Am going to put a couple degree bottom pill in and stand the kingpin up more to take more caster out and see what he thinks and what the stopwatch says.
I don’t think the stock OTK wheels will help at all, those are almost never run and especially not in high-grip conditions. MXC’s or 9F’s would be my recommendation.
As a taller driver, I found removing seat struts tended to help a ton with keeping the kart free, so I wouldn’t worry about putting them back on. I would see how far you can get with removing caster and narrowing the front. I would hazard a guess that the wheels are really hurting you guys though.
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A couple things for sure:
Too wide in the front - that is almost full wide, rain setup width. 2 small spacers is more than enough for a 206 particularly if you are already having mid corner issues.
MXC or even MXL/MXQ wheels. With all due respect Douglas wheels are kinda awful. As noted above the MXJ is too soft for a tall driver, particularly in the heat. If you make no changes or take no other advice, change the wheels as noted multiple times above.
Rear ride height/seat mount position. I have a pretty good driver at my disposal still with great feedback who comes out and runs the 206 for fun here and there. He’s a solid 6’2” 185 pounds now and the only way we could be on pace was to drop the frame to the lowest position. At 6’4”, particularly in the heat, low ride height is non-negotiable. Also I’d probably have the seat 2-3mm below the frame rails. Particularly if you are going to stick with the OTK seat as you’ll probably blow through the bottom but OTK 2 seats are cheap and plentiful.
Me personally I’d also be in a T11t with struts at 2-3mm below the rails. But blowing through the bottom of Tillett seats isn’t an appealing idea financially speaking.
Lastly, saying this in the most polite way possible… How much input a driver gets needs to be moderated. Lol. Sometimes you just need to do what’s right because you have guys like TJ, Evan, etc that have spent 20+ years exhausting the options already.
Ride height
Seat height
Right wheels
Front width
Have any pics of him rolling through the entry of a corner?
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No seat struts is the way to go in 206 with a tall driver. I worked with a taller guy this last year and we struggled until we took the struts off. Kart was always too stiff and hoppy and his ribs were destroyed every session. Took struts off and the kart immediately calmed down and we could start tuning again.
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What seat were you using TJ?
My concern with a bigger guy and no struts is the load on the stays themselves. Have just had so many stay welds break the last few years that I’m probably default going to struts to protect the kart at the driver’s expense. Might need to revisit that.
This is where we have arrived. He hurt ribs last summer, which is what drove us to tune without stays. I have gone back and tried em a few times, but found he could usually find more speed by other tuning options when grip got low. We seem to have lower grip figured pretty well for relative newbs.
Going to order some MXCs before our next NTK weekend. Enough people recommending them.
On the seat struts, they will be last on the list of things we try. It made our already narrow tuning window even smaller last summer.
Trust me I get the point. Working with a 16 year old son can be a challenge. If I had more karting background it would help. Unfortunately I know 13 months worth of tuning, just like he knows 13 months worth behind the wheel. Makes for a lack of confidence in tuner dad. Something we are both working on.
Let me see what he has. Should have some on board stuff? I don’t have much on my phone from the two recent hot races. Was hiding in the shade of the stands instead of hugging the fence like normal. The triple digits were killing me.
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Tips on seat adjustment? I am scratching my head trying to figure out where we find 10 mm back and 20-25mm down given where the seat struts are right now? Further down and back is gonna have the struts bolt on the lip of the seat? 
I have these two handy from my phone. Two weeks ago. We were junk both weekends and the 8/9 flat turn and 3 banked turn both exit onto straights and were killing him on lap time.
Merlin on T11 VG and OTK on T11 VG.
Could just leave the chrome struts sloppy loose so if you bust a chassis strut you at least have those to keep your driver from falling out of the kart.
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Was really interested in tuning the rear ride height after reading some of your comments on it. Would I fall into the tall driver category? I’m around 6ft but not a lot of body weight at around 135-140.
Recently put an angled block on the wheel and seemed to help me “work” the kart a little more, Definitely resonated with your description of the kart being on top of the track. That’s something I seem to say to myself at the track.
(206 engine)
(Also looking for hundredths at this track at this point sometimes so definitely super close already)
At 6ft I wouldn’t think you would need the ride height but you’re light so it could be worth trying to see how you like it.
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When trying to make good set up for different track conditions
The slower one drives in the corners - more rear lift is needed as theres no g forces helping with the lift. For example racing in the rain. Or if the driver isnt up to pace
As the lap times improve, speed increases at the corners, the g forces increase. G forces are a lift multiplier - so much that if not compensated by reducing caster, front width, at some point the kart frame over twists from combining mechanical lift + g forces. Gets loaded like a spring. This spring load/unload cycling makes the kart hop
After making set up changes that reduce rear lift - its important to keep good attack/speed on the corners. The g forces are now that lift the inside rear and if set up is good - it does it just barely. Caveat is that one must now have the stamina to keep this fast pace through out the race distance. Slowing down with this setup is a no no. Reduced g forces dont have enough force to lift inside rear, front has little mechanical jacking = makes the kart handle bad at the corners
If one can find a set up that the kart stops hopping - adding seat struts give faster pressure input. The g forces can do the lifting in a timely manner early enough
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You are definitely bound by the stays to a degree. You can go back until you stop a few mm from burying the tip of the stay inside the rolled edge. If it is difficult to get hardware on with it that far back, you can use a 2” flap wheel to create a crescent shaped cut in to the lip so you can get a nut on. Just don’t want the seat hitting the secondary support on the right side stay. That’ll end up being your stop.
2-3 mm below to be sure though - 20-25mm will put his butt on the ground. 
As much as I’m a Tillett fan, the shallowness of the OTK probably lets you get a little further back in comparison.
Some updated information that was incorrect or incomplete:
We were at 5mm of camber last weekend! 
Front/Rear weight is spot on at 42.5%
Lead us currently located 10 up front, 5 under left front of seat, 5 on left side of seat, 5 on back left at about break caliper height.
Asked him about leaning and got really muddled feedback. He said it helped when it was cooler earlier in the year. He said wasn’t leaning much in the heat now, but didn’t get a clear answer as to why.
After more discussion with him, I am convinced he is overdriving entry and not carrying enough speed mid corner resulting in inconsistent rear tire lift and early/inconsistent set down. If he drives corner correctly in the heat it beats him to death hopping. The heat amplifies the negative impact. No way to tune for that and driver is hard headed when I offer feedback as a non driver. He is gonna have to hear from someone that isn’t dad.
So off to Amarillo with no clear path forward for us this weekend! At least it isn’t known for grip!
Is coaching in the cards?
Yes. We worked with a coach last summer when my son plateaued some and made more gains. Unfortunately that coach has moved on to be the lead driver coach and race engineer on a full size sports car program. Working on lining up someone we can meet up with.
I’ve had good results doing video coaching with TJ and Warren. I would send a race and TJ would deconstruct where I was a moron, for example.
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You son and I share a lot in common. I am 6’9", 210 lbs (what is your son’s weight?) and also run an OTK at my home track, NTK. Summer there is a tough. Turn 7 is the worst for Hopping, 8 & 9 aren’t too bad.
I run the large Tillet T11 vg. OTK seats don’t get large enough for my hips. You have to mount them from axle to seat back to get the dimensions right and slightly offset a/b measures like OTK prescribes.
Depending on your son’s weight the camber will change when he is sitting in the kart versus on the stand. Running 3 degrees of negative front camber can take front grip out of the kart. Too negative and the tire cannot make full contact with the road. Its hard to measure, but will be evident by the wear pattern on the front tires. Too negative and the outside edge of the tire will have little to no wear and the inside will be blistered. Take out camber until you get good contact on the outside edge of the tire.
When the grip comes up at NTK you have to take caster out and narrow the front. I wouldn’t mess with the tire pressures too much, just adjust them for your target hot pressure when you come off track. You can also try a harder axle, but that’s a big change. MXC wheels can help with stabilizing tire temps over the course of a run. I have used both the OTK wheels and Douglas. The OTK wheels are more consistent. Lowering the rear ride height will help bring down his COG. I am too heavy and my frame has a little sag, so I cannot drop my rear ride height. Instead I recline my seat more instead. It means the front edge of my seat is at or near the top of the frame rails, while the back is at or just below the frame rails. This helps get my shoulders down and lowers my COG. When you start jumping curbs at NTK you will destroy your seat if its too low. Moving the seat slightly forward will also take some weight off the rear axle, but it sounds like your balance is on point already. When I first started racing, I struggled with an extreme hop in turn 7. After sharing my issues with fellow racers on and off this forum, I made the the following adjustments.
Took Caster out.
Narrowed front track.
Moved my seat forward and leaned it back more.
Changed to an H axle.
No addition seat struts.
Widened rear track to max limit.
Slowed down my corner entry, got the kart rotated earlier and tried to be as straight as possible at apex. (the straighter you are, the sooner you can get back to throttle without inducing a hop!)
Try to stay under the rubber (see Ryan Norberg’s video for explanation).
By doing all of this, I have given myself a larger tuning window and maximized the tire side bite while reducing or eliminating the hop. Last summer I had so much grip, I would often bicycle at the apex of T7. The first time it happened I nearly flipped the kart over. Luckily I caught it by decreasing throttle input and opening up the steering wheel. I lost more time than if I had just slowed my corner entry a little more. Now I can just barely feel the inside wheels leave the ground, if at all. If he starts to bicycle, tell him to try leaning into the corner or slow his entry slightly.
For turns 8 & 9, you need to turn in later so that you late apex climbing the curb of 7 and set up for another late apex (straightening the corner) kissing/bouncing off the curb of 8 and fading out to the edge of the track. That should give him a nice exit onto the back straight that he can carry more speed to turn 1.
Sometimes slowing your entry can make your exit faster. Over do it and you put the kart in a bind and kill your exit momentum or you ask too much from the tires and you end up with a severe hop also killing you exit momentum.
P.S. Good luck in Amarillo! Maybe I will see you at NTK Summer 3.
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