Picking up speed with a heavy driver

[Kent Metcalf]

Ok my post on the TD23 clutch went well and a big help. Now I need help on a heavy driver issue. So here it go's:
My driver races the Yamaha Jr class 305 weight
Going over the scales he weighs 358 lb
Now he's every bit 5'6 and weighs 201
My issue is we race with a kid that hits the min weigh of 305 and is a short kid to say the least. This kid is about a second and half faster than us. I know this is an issue that I might not be able to get the answer I'm looking for but it don't hurt to ask. maybe I'm over looking something. air pressure, set up ,ect.
I went down a tooth and it slowed us down and I'm afraid that if I go up a tooth it will slow us down on the straights. We do great in the corners but loose time on the straights. I need more straight away speed. He works on tuning the carb on the straights and seems to do good. I don't know if thats where he needs the help the most?
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St. louis Mo.

[Rob Kozakowski]

[Walt Gifford]

That's a BMI of 32.4

For me kart racing was a strong motivation to overhaul my diet. A few simple changes can really make a big difference in ones health and lap times. I consider it part of driver development.


Gif

[John Wehrheim]

You need to give more details such as what is your Rpm, what track, what rpm does your clutch engage, what is your carb setting. Where do you think you are losing most against your competition?

As a general rule with that weight difference you can expect approx 5/10ths slower. Now you need to find the other 1 second. You will need to add gear to pull out of the corners especially if you have tight corners. Your clutch should engage around 8,800 rpm.

[Kent Metcalf]

Thanks guys. Ya I know and am willing to except the weight challenge due to his weight BUT of course we love to win. Can't wait untill he moves into SR. so the weight will not be a disadvantage like it is now.
John heres a few things I do know:
RPM's: He's turning around 13300 give or take
Stall is set at around 8200 give or take. just put new friction disc and rotor in it and am working on getting that set. Tryed it on the old clutch at 8800 but it seemed not to help. it seemed if I set it more to a rookie clutch around 7900 to 8200 he did better. ???
NO added weight to the kart
The track is TNT in Quincy IL. we are running 11/86 gears some say drop down to a 10 tooth on the front but I really don't understand that because I'm told you need to change the rear gear then. Thinking that will just put me right back where I'm at now? He dose fine and catches other drivers in the corners, it's the straights he looses ground on. went down to a 85 rear gear and it slowed him down. Guessing he was not getting off that last corner good enough to get the straight away speed. Thanks for the help guys keep the ideas coming. like I said as long as I can get though this year I'm happy. we understand our challanges and are willing to except what it means to us. Another reason we can't wait to get into the Sr. class.
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St. louis Mo.

[Kent Metcalf]

Generally when we ran a heavy class, we would add 1-2 teeth in the back. That said, we'd still be a few tenths slower. And this was with 25+ hp and adding 40 lbs.

At 50 lbs over and with an engine restricted to under 15 hp, realistically there's nothing you can do with tuning to be competitive if the competition is decent. 1.5 secs off might not be that bad given your situation.[/quote]

Yes we understand the spot we are in. Heres the kicker (and I know its a big player in all of this)
My driver TALL and built @ 199 plus kart = 385 adult kart
other driver real short @ (guessing) 120 plus added weight =307 cadet kart
Just sucks to see the disadvantage we are in. Bryan really loves the sport and knows when he hits Sr. class he better off. Just see to many people in our sport that have heavy kids walk away and give up. I'm not saying my kids fat just big boned for his height. heck he's 5'7 at 14 years old.
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St. louis Mo.

[John Wehrheim]

[Kent Metcalf]

we run the low side at 1&1/4 to start. normally he comes off the track at 1&1/2 open. The high side just barely open. We try'd to open the high side to 1/4 but no change, maybe a little slower.
So your saying if I stick with a 11 tooth on the front go to a 88 on the rear? OR drop down to a 10 tooth and go to a 82 on the rear?
The motor was built at the end of last season by SLK Motors a man names Charley here in st louis.
I know coming out of the last corner he is usully on the back of another driver and has to try to get around him coming off the turn. Then when he can't he tucks under neith him untill ge gets going ahain. Thinking he's scrubing off speed there and not getting it back on the straight before he hits the 1st turn.
So if I go to a 10/82 vs a 11/89 what is that going to do for me exactly?
Thanks for your time by the way.
Do you think if he backs off before the last turn (lets say 2 kart lengths going into the last turn) he might keep the speed and catch the front driver going down the straight?
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St. louis Mo.

[TJ Koyen]

Like John said, you're WAY low on RPM. Mid 14k where you should be.

And being 50 pounds over minimum weight, he'll never be as competitive as the kids who are at the weight limit. 50 pounds is massive in karting especially. 40 pounds between the Komet Lite and Heavy classes was usually several tenths and the Komet has more power.

Also, not sure how your engine is built, but we usually ran around 2 1/4 on the low around 1/4 on the high for carb settings with the Yamaha, so that's pretty far off what you're running.
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T.J. Koyen
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DB Motorsports
Exprit/Leopard

[Kent Metcalf]

you know I cant get the motor to run with it open to 2 1/2 turns. I am well aware that the weight disadvantage is going to keep us from keeping up with this kid. It's more that I am concerned about getting all I can get out of my drive. Thinking if I can get close to adv. track times with a heavy driver he will be at the top of his game by time he reaches yamaha sr. at the min. 360 weight.
Thank you for all your honesty and it don't hurt my feelings. like Walt says its a part of driver development.
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St. louis Mo.

[JT Miles]

I've ran many laps around TNT... If you are talking about the Monza corner before the longer straight, id try to lift a bit sooner before entering...Trying to go too fast in it will scrub speed down causing catch up on straight...That corner is all about keeping it smooth and momentum up...
TJ is correct, I always ran 2 1/4-2 1/2 on low side depending on weather..For the high side, When adkins built my engines we ran it closed and with swedetech it was 1/8-1/4...
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Miles Racing
2nd Place 2012 Kid Kart Nationals
Energy Kid Kart/ CKS C51
Birel Kid Kart/ LAD C51 #7C
Intrepid/MY09 Comet Leopard #722
Emmick/K78 and TT25

[Kent Metcalf]

That's the spot JT I'm trying to teach him to back off a little and drive though the Monza so he's not riding the guy in front of him bumper. They get loose and he is forced to slow down and I'm thinking he's having trouble getting it wound up again.
So if I go to a 10/82 vs a 11/89 what is that going to do for me exactly?
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St. louis Mo.

[John Wehrheim]

[Kent Metcalf]

Ok so guessing the 10 tooth on the front gives you more revolutions spinning the chain faster and the same on the rear? sorry to sound stupid but I never figure the gearing out right. It seems with a heavy driver I can't do what most do with the little drivers.
On the turning the low side out 2 1/2 I could not get it to run on the stand or start on the grid. So thats why we start at 1 1/4 and by time he comes off the track he has it open to 1/12 or just a little more. I guess we will try to open it up during practice and see what it dose.
Thanks for all the help
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St. louis Mo.

[John Wehrheim]