Weighing your Kart on Raceday

@Eric_Gunderson took some time last weekend to make this video for newcomers to the sport.
Classic case of a topic that seems simple to those of us racing for years, but is not always well understood by someone who’s just getting started in competition karting.

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Cool. For us noobs, what do you want to do before you weigh in? What amount of fuel in the tank etc?
Do you scale yourself before each race to make sure you haven’t lost a few pounds from week to week?

@Bimodal_Rocket I’d recommend (especially for a new driver that isn’t on the knife edge) to always scale with an empty tank. Make min weight with the tank empty, and then ballast with fuel in the tank. You can of course do this different ways, but it’s just an easy way to ensure that you’ll be good on race day.

The other thing I tell people is do your best to be at least 5 lbs over. I know, I know, I know…“but muh speed.” Man, unless you’re 10 lbs or more over, you’re not going to notice much difference. The reason I say this is because no matter the scale set or weather etc the scales can ‘swing’ from one part of the day to another in terms of what they will read in terms of weight. The load cells are sensitive to moisture and temperature, so it’s not super uncommon for them to go +/- 10 lbs in a race day if it’s a cold morning and a hot afternoon. For this reason, I recommend always having a small cushion.

When I was racing, we always weighed the kart first thing in the morning on race day, and of course would scale in the shop before ever testing with a new kart. Almost always we were good…but that one time you don’t check…

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Thank you! Useful to know.

While we are on it, should I be scaling the cart across the 4 corners? I’ll likely be attaching 15-20 lbs of lead to the seat.
The idea is to have the weight the same on the 4 corners? Or at least the same across fronts and backs (assuming you can’t make the front weigh the same as back).

IE:

1lb. 1lb.

2lb. 2lb.

Here’s a couple resources for scaling:
AlignYourKart04-08.pdf (425.1 KB)


If you don’t have access to scales, put your weight on the left side of the seat and under the left front “wing” of the seat. That will get you in the ball park.

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Awesome. Thank you. :+1::+1::+1:

@Bimodal_Rocket most karting manufacturers and dealers will have a basic front to rear ratio for you. A common ratio I’ve seen is 52 rear 48% front weight percentage. Almost all digital scale systems (or simple math) can tell you this.

From left to right or corner wheel weights is trickier. This will depend on the engine, kart, setup, etc.

Thanks. We slapped on 25 lbs of lead on the back of the seat so I am guessing my weight distribution is weird.

Hate to be “that guy”, but 48% front seems super high, I’ve never seen any manufacturer recommend that. Every range I’ve seen is between 41-44% front depending on driver size. I know I’ve always been around 42-43% front using manufacturer recommended seat placement. I couldn’t get to 48% front if I wanted to. There would be like 40 pounds of lead in front of the gas tank.

@tjkoyen thank you for catching my mistake! Wrote that comment at 4 am…must have been thinking about legends cars! Those numbers are pretty typical for a legend, although reversed…

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