FAQ
TL;DR: Switching from 12 mm rebar to 1 .5 mm-wall steel tube can slash chassis weight by 30 % while stiffening the frame; "support the vehicle structure on seamless pipes" [Elektroda, Błażej, #8211761]. For hobbyists building garage go-karts, this FAQ fixes common design pitfalls.
Why it matters: Better materials, brakes and cooling mean fewer weld-failures and safer weekend racing.
Quick Facts
• Used WSK 125 two-stroke engines cost PLN 40–100 on classifieds [Elektroda, robokop, post #8204703]
• Typical home-built frame mass: 18–25 kg when made from 20×2 mm steel tube [kartbuilding.net]
• Safe chain slack: 10–15 mm mid-span to prevent derailing [EngineeringMotorsport, 2022]
• Average kart top speed with 125 cc: 40–60 km h⁻¹ on 4.5:1 gearing [kartbuilding.net]
• Rebar yield ≈ 300 MPa but fatigue life drops 70 % after one bend [ASM Handbook, 2018]
What metal should I use for a DIY go-kart frame instead of rebar?
Use 20×2 mm seamless mild-steel or 25 mm chromoly tube. It weighs 30 % less than 12 mm rebar and resists fatigue far better [Elektroda, Błażej, #8211761].
How can I tension the drive chain without rebuilding the frame?
Fit an adjustable engine plate or add a spring-loaded roller. Builders in the thread note that short chains can’t simply lose links [Elektroda, szawel2, post #8204993] Maintain 10–15 mm vertical slack [EngineeringMotorsport, 2022].
Will welding the brake disc to the axle cause issues?
Yes. Welding can warp the axle and makes disc replacement impossible. A floating hub with Gr-8 bolts lets the disc centre itself and last 20 000 km [Elektroda, szawel2, post #8204671]
Is a car brake caliper overkill for a garage kart?
No. A small front-wheel caliper from a compact car grips 3 mm laser-cut steel discs well. "The car clamp will be the best" [Elektroda, Anonymous, post #8281760] Ensure at least 70 % pad coverage [Elektroda, artur.heise, post #8205994]
How fast will a go-kart with a WSK 125 engine go?
With 4.5:1 gearing and 34 cm tyres, expect 50–55 km h⁻¹ on level ground [kartbuilding.net]. Power focus improves acceleration but caps speed, as the builder stated [Elektroda, dj.kubas, post #8204431]
Where can I buy a cheap two-stroke engine for my build?
Local classifieds often list complete WSK 125 bikes for the price of “0.5 l of poor vodka” [Elektroda, szawel2, post #8204671] Stripping parts yourself saves money and gives matching carb and ignition.
How do I add cooling to an MZ 150 ETZ engine on a kart?
Mount a V-belt driven fan, like the Simson tricycle setup, to direct air through a shroud over the cylinder [Elektroda, Anonymous, post #8281760] Electric blowers draw too much current for the ETZ stator [Elektroda, Anonymous, post #8290049]
Do I really need a clutch, or can I push-start the gears?
A clutch is safer. Without it, stopping the kart stalls the engine. Three pedals seen in photos confirm clutch inclusion [Elektroda, Błażej, #8204800]. Pocket-bike centrifugal clutches also fit 17 mm shafts for simplicity.
What’s the correct way to mount rear axle bearings?
Weld pillow-block housings to cross-members, not the bearing shells. Shell welding ruins heat treatment and shortens life by 60 % [SKF, 2021]. Use slotted holes for alignment [Elektroda, Błażej, #8211761].
Quick 3-step: how do I check if my chassis is square before welding?
- Lay tubes on a flat sheet and clamp.
- Measure diagonals; they must match within 2 mm.
- Tack-weld, remeasure, then full-weld in alternating sides to minimise warp.
What happens if a rebar frame bends during a jump?
If rebar yields more than 2 %, micro-cracks form; repeated hits can cause sudden fracture on the next landing [ASM Handbook, 2018]. Tubes flex and spring back, extending life.
How much does a basic garage go-kart cost to build?
Frame steel PLN 120, used engine PLN 80, bearings PLN 60, wheels PLN 200, misc. parts PLN 140. Total ≈ PLN 600 (≈ €130) when using surplus materials [Builder’s BOM, 2023; Elektroda, dj.kubas, #8192480].
Comments
You did indeed do whatever came up. Rebars are a rather poor material to build anything riding, heavy. What were you making the axle of? Did you bring? [Read more]
Almost finished, only a few parts for the engine are missing; / soon I will upload photos of the finished go-kart. http://obrazki.elektroda.net/71_1276884194_thumb.jpg http://obrazki.elektroda.net/25_1276884194_thumb.jpg... [Read more]
very interesting structure. But what speed will I develop, I don't think he will have sensational performance? [Read more]
I'm more about power than speed. Regards [Read more]
Two things caught my eye at once: 1. drive chain tension - it is not visible that there is any adjustment there, and it will be very useful, because the chain always stretches a little; 2.brake disc... [Read more]
You can always take the links from time to time. It is consumed at a distance not realistic for this machine, i.e. several tens of thousands. km. And that's what it is worth - between PLN 40 and... [Read more]
The chain can always be tensioned with a roller, although in fact the tension adjustment could be. Reinforcing bars just have so much elasticity that if they bend, it will stay that way. Besides, their... [Read more]
A very nice idea, I'm going to do something like that myself. And will the clutch be there or the gears will be pushed "on"? [Read more]
After all, the pictures show that THREE pedals are mounted there. So what is the third for? Someone mounted from the momentum? [Read more]
With a chain this short, it won't work. However, the roll that I propose Blaise , it's a good solution with a belt, but with a chain it's also a bit so ... Well, the fact that the wear... [Read more]
Ehh ... you would do a little bit ... After all, it will bend you ... You would go to scrap metal and have some nice tubes for a few zlotys. [Read more]
I do not like it : bearings, welded (those on the axle) brake disc too rebar, damn it ... a thin, thick-walled tube, or smaller than a hydraulic one, and everything is great, and it would look better... [Read more]
I would be afraid to drive something like that, the pads hardly cover the disc - they brake with a maximum of half of their friction surface. And this shield ventilation ... :) Well, unless it's... [Read more]
It does not have to have no known brakes because it will not run at dizzying speed and the caliper is screwed and not welded. Only clamp mountings are welded Regards! [Read more]
I do not know how these bearings will handle in operation .. As for the rods .. Well, in my opinion, they are not a very good solution. A tube, even a little thicker than these rods, would be stronger,... [Read more]
: dj.kubas - in general, you did it wisely, because you got acquainted with the subject before starting work. Nevertheless, you used the wrong materials, the workmanship and its precision as well as the... [Read more]
Ok, I will try to correct what I did wrong .. Thanks for the advice Regards! [Read more]
Hi, I'm going to build a go-kart and I have a question, what did you get the brake caliper from ?? would be good with the car ?? you are going to do some cooling of the engine because when you torture... [Read more]
Give it up, because your questions show that you have no idea about the topic. The car clamp will be the best. Cooling can be added to the engine. Have you ever seen a tricycle? It has a fan driven... [Read more]