The chain is the part nobody thinks about until it slaps a guard, jumps a sprocket, or snaps coming off the cushion and hands the win to the guy behind you. It's also one of the cheapest things on the kart. A little attention on the trailer beats a DNF every single time, so let's walk through sizing, tension, and the between-heat care that keeps your outlaw kart driving off the corner the same in the last main as it did in hot laps.
#35 is the standard — know what you're running
Just about every outlaw and flat kart on dirt runs #35 chain. That number isn't marketing — it describes the chain's dimensions. The "35" means a 3/8" pitch (the distance from one pin to the next) and a 3/16" roller width. Match that to #35 sprockets and a #35 clutch driver and everything meshes the way it should. Mix pitches and you'll chew teeth in a night.
Chains come in a set number of links, and you size them to your setup by adding or removing links with a chain breaker. A quality racing chain like the RLV Xtreme runs lighter than a hardware-store chain, and less rotating weight means quicker acceleration off the corner — exactly where dirt karts live.
Master link vs. riveted
Most of us run a master link (the clip-style connector) because it lets you pull the chain in seconds to swap gears or clean it. One rule that saves chains: the closed end of the master link clip faces the direction of travel, so the spinning chain never catches the open end and pops it off. Check that clip every time you install a chain. If you're chasing every ounce and never breaking the chain trackside, a riveted link is an option — but for how often outlaw guys change gearing, the master link wins.
Setting chain tension: the 1/2" to 3/4" rule
This is where most drivetrain problems start. Too tight and you bind the chain, rob horsepower, and grind sprocket teeth down in record time. Too loose and it slaps the guard, climbs the sprocket, and eventually throws itself into the dirt. The window you're shooting for is about 1/2" to 3/4" of free play at the middle of the bottom run.
Press the midpoint of the chain up and down with a finger. You want it to move that half-inch to three-quarter-inch and no more. It should feel snug but never guitar-string tight.
How to adjust it on the kart
On an outlaw kart, chain tension is set by moving the engine, not the axle. Break the motor-mount adjuster loose, slightly loosen the engine clamps, and slide the motor forward to tighten or back to loosen. Snug the clamps up gradually and re-check the play as you go. When it's in the window, torque the clamps and adjuster and re-check one more time — clamps love to pull the motor a hair as they tighten. If your mount setup is fighting you, our American vs. International rail guide breaks down how the two mount standards move the engine.
Find the tight spot first
Chains and sprockets are never perfectly concentric. Before you set final tension, roll the rear tire slowly through a full revolution and watch the bottom run — you'll find a tight spot and a loose spot. Set your 1/2"–3/4" of play at the tightest point of that rotation. If you set it loose there, the loose spot elsewhere will be flopping around. A worn chain or sprocket makes that tight/loose swing bigger, which is a clue it's time for fresh parts.
Cleaning and lubing between heats
Dirt racing is brutal on a chain. Clay, dust, and grit turn chain lube into grinding paste, so a race chain isn't a "set it and forget it" deal. Between heats, knock the packed dirt off, wipe the chain down, and hit it with a light chain lube that penetrates the rollers without staying tacky enough to grab more dirt. A thin penetrating lube like Tri-Flow gets into the pins and rollers where wear actually happens.
Two things to avoid: don't drown it in heavy, sticky oil that turns into a dirt magnet, and don't run it bone dry "because it just picks up dust anyway." A lightly lubed chain wears far slower than a dry one — the goal is lubrication inside the roller, not a coating on the outside.
When to replace it: chain stretch and the ruler test
Chains don't actually stretch — the pins and rollers wear, and all that slop adds up so the chain rides higher on the sprocket teeth. Run it too far and it starts hooking the teeth and wearing your sprockets and driver right along with it, which turns a cheap fix into an expensive one.
Quick trackside check: pull the chain back off the rear sprocket with your fingers. If you can lift a link far enough to see a lot of daylight over the tooth, it's stretched. For a real measurement, lay a chain out and measure across a run of links — on a fresh #35 chain each pin is 3/8" apart, so a section that measures noticeably long is worn out. Other tells: a growing tight/loose spot when you roll the axle, teeth that are starting to look like shark fins, or a chain that won't hold tension for a full night. When in doubt, a fresh #35 racing chain is one of the cheapest pieces of insurance you can buy.
Your quick pre-race chain checklist
Before you roll off the trailer, run through this:
- Play: 1/2" to 3/4" at the tight spot on the bottom run.
- Master link: clip closed-end facing the direction of travel, fully seated.
- Alignment: clutch driver and axle sprocket in the same plane so the chain runs straight.
- Lube: light, penetrating, wiped of packed dirt.
- Guard: chain guard bolts tight so nothing walks loose mid-main.
Since gearing changes with the track, your chain length and tension will shift right along with your sprocket choices — if you're dialing in ratios, pair this with our outlaw kart gearing guide, and if the slop is coming from the back of the kart, the rear axle & hub guide covers where else that play hides.
Ready to freshen up the drivetrain?
Keep a spare chain in the trailer — you'll use it. Grab a fresh #35 racing chain, a chain breaker and the right tools, and chain lube to keep it living. Need help matching chain, sprockets, and a clutch driver to your class and track? Give the shop a call — we race this stuff too, and we'll get you sorted.