# Build a Go-Kart: Calculations & Planning

• JOHN daruwala
In summary, the person is planning to build a go-kart, and has purchased an engine with specifications of power (8.2 kW, or 11.1 PS) and torque (11 N-m, or 5.9 kg-m). The calculations show that the kart will have a rolling force of 221 N and a drag force of 26 N. The kart's total tractive force will be 221 + 26 = 247 N, and the torque at the wheel will be 247 X 0.1 (20 cm wheels). The person has calculated power (Ft X vmax) and found that the gear ratio is 3.7. The axle teeth are estimated to be 52. The person is at the
JOHN daruwala
so i am planning to build a go kart
i have purchased the engine with following specs:
power =8.2 KW (11.1 Ps) @8000 rpm
torque= 11N-m @5000 rpm
Calculations:
rolling force=221 N
drag force=26 N
total tractive force=221+26=247N
torque at wheel= 247 X 0.1 ( 20 cm wheels)
= 24.7
then i calculated power =Ft X vmax
=247 X 23/1000 =5.68 KW (23m/s is limit at my track)
the i calculated wheel rpm=2100 by power rpm torque relation
found out the gear ratio =engine rpm/wheel rpm
=3.7
14X3.7=axle teeth
52=axle teeth i am at planning stage i want to know if iam right uptill now or wrong
all so want to know how to calculate pitch of teeth if i want to cast the sprocket

Last edited:
good effort and you are on the right track
how much do you weigh?
what is the estimated weight of the kart?
is final drive live axle or dead axle?
i would worry about final sprocket selection at the last. go with number 35 or 41 roller chain.
it would help me if i knew horsepower and torque in ft. lbs

i have taken gokart+my weight as 330 lb (150kg)
i would be using dead axle
Engine- torque 8.79 ft-lbs
power - 11 hp
is there a criteria for selecting roller chain ?

#35 roller chain is typical for your HP application. wheelbase around 41" and 41" track width is good. big sprocket on axle 72 tooth.
the clutch could be 10 tooth or 12 tooth. Kart should weigh 130 to 150 pounds. you need to consider live axle to get max performance.

i would agree with you on live axle,
but increasing tooth on axle sprocket would reduce my top speed

Ranger Mike said:
big sprocket on axle 72 tooth.
the clutch could be 10 tooth or 12 tooth.

If his top speed is 23 m/s (51 mph) and his tire diameter is 20 cm (7.875"), that would give an engine rpm between 13200 & 15800 rpm. I don't think it will work with his 8000 rpm engine.

i was thinking 14 tooth clutch and 56 rear sprocket clutch with 1:4 ratio
what time will my clutch survive if i use this ratio

jack as usual is right.
i did not do the math...from stricktly experience and what common final ratios are around here
i was referring to typical 6:1 or 7:1 final ratio most karts run..5:1 is getting too high and i think 4:1 will be real slow from the start. 7:1 is a stump puller gear and 6:1 is a good happy balance

Last edited:
if i were to cast the sprocket , could you tell me something about the pitch ratio of the teeth ?
TY.

#35 roller chain is fastest but # 40 or 41 is heavy duty for your weight kart..i don't trust cast parts , forged is much stronger for racing

## 1. How do I calculate the speed of my go-kart?

The speed of a go-kart can be calculated by dividing the distance traveled by the time it took to travel that distance. To determine the distance traveled, measure the circumference of the wheels and multiply it by the number of rotations made in a given time. The time can be measured using a stopwatch or a timer. Divide the distance by the time to get the speed in units of distance per time (e.g. miles per hour).

## 2. How do I determine the size of the engine needed for my go-kart?

The size of the engine needed for a go-kart depends on the weight of the go-kart and the desired speed. Generally, a 5-7 horsepower engine is suitable for a lightweight go-kart, while a heavier go-kart may require a larger engine. It is important to also consider the terrain and the rider's experience when determining the size of the engine.

## 3. How do I calculate the weight distribution for my go-kart?

The weight distribution for a go-kart is important for optimal handling and performance. To calculate the weight distribution, first determine the total weight of the go-kart, including the rider. Then, divide the weight by four to get the weight on each wheel. Ideally, the weight should be evenly distributed on all four wheels for balanced handling.

## 4. How do I plan the dimensions of my go-kart?

The dimensions of a go-kart can be planned by first determining the desired size of the go-kart based on the rider's height and weight. Then, consider the space needed for the engine, steering mechanism, and other components. It is important to also consider the weight distribution and center of gravity when planning the dimensions to ensure stability and balance.

## 5. How do I ensure safety when building a go-kart?

Safety is a top priority when building a go-kart. It is important to follow all safety guidelines and regulations, such as wearing proper safety gear and ensuring the go-kart is structurally sound. Additionally, regularly inspect and maintain the go-kart to ensure it is safe to ride. It is also important to never operate the go-kart under the influence of drugs or alcohol.

• Mechanical Engineering
Replies
1
Views
766
• Mechanical Engineering
Replies
20
Views
4K
• Mechanical Engineering
Replies
8
Views
3K
• General Engineering
Replies
2
Views
3K
• Mechanical Engineering
Replies
2
Views
4K
• General Engineering
Replies
3
Views
6K
• Electrical Engineering
Replies
2
Views
1K
• Mechanical Engineering
Replies
7
Views
2K
• Mechanical Engineering
Replies
4
Views
3K
• Electrical Engineering
Replies
15
Views
2K