Short answer. Our 50cc tops out at 32 mph on flat ground with a light rider. Most 50cc mini dirt bikes land somewhere between 20 and 40 mph, and the spread comes down to two stroke against four stroke, gearing, and whether the bike has a working governor.
The more useful answer is that on any bike with a governor screw, the top speed is a number you set. Ours will do a walking jog if you want it to. Here is how all of that works.
Why 50cc bikes vary so much
Engine size on its own tells you almost nothing. Two bikes can both say 50cc and be 15 mph apart. Three things decide it:
Two stroke or four stroke. A two stroke fires every revolution instead of every other one, so for the same 50cc it makes more power and revs higher. Ours is a two stroke. A 50cc four stroke of the same size is usually the slower and gentler of the two, which some parents prefer and some kids find boring.
Gearing. The sprocket sizes decide whether the engine's power goes into pull or into speed. A bike geared for a steep yard will top out lower than the same engine geared for a flat field. This is also why a seller's number and your number can differ on the identical bike.
The governor. Most mini bikes have a screw on the carburetor that physically limits how far the throttle opens. If a seller quotes a low number, sometimes that is the bike, and sometimes it is just the screw turned in. Worth asking which.
What actually changes your bike's speed day to day
32 mph is with a light rider, on flat, hard ground, with the bike set up right. Real riding is rarely all three. In rough order of how much they matter:
- Rider weight. The single biggest one. A 60 lb kid and a 160 lb adult will see a real difference on the same bike.
- Ground. Loose sand, deep dirt and grass all eat speed. Hard pack is where you see the top number.
- Slope. Obvious, but worth saying. Nobody hits top speed going uphill.
- Chain tension. Too tight drags, too loose slaps and robs power. Set it properly and you get free speed back.
- Air filter. A filter clogged with dust chokes the engine. Out here that happens fast. Clean it.
- Fuel mix and the spark plug. Stale or badly mixed fuel, or a fouled plug, and the bike feels gutless. 25 to 1 and a clean plug.
- Tire pressure. Soft tires drag. A gauge costs almost nothing.
If your bike used to feel quicker and now does not, go down that list in order. It is almost always the filter or the fuel, not the engine.
How to make it slower, which is the question most parents are really asking
You do not have to accept 32 mph. There is a governor screw on the carburetor that caps how far the throttle will open. Turn it in and the bike will barely outrun a jog. Open it a quarter turn at a time over the first few weeks as your kid earns it.
This is the most important thing on the whole page, so to be plain: a 32 mph bike with the screw turned down is a 5 mph bike. Buying a slower bike to be safe usually means buying a bike your kid outgrows in a season, when you could have bought this one and opened it up as they got better.
Which screw and which way it turns is in how to adjust the speed limiter. It takes about two minutes and a flathead.
What speed is right for a new rider
We are not going to pretend there is an official chart, because there is not. What we tell people who text us:
- First session: walking pace. Fast enough to balance, slow enough that stepping off is nothing. They should be learning the brakes, not the throttle.
- Once they can stop on purpose, every time: open it up a little. Still slower than they can run.
- Once they can turn both ways without looking at the bars: a bit more again.
- Wide open: when they ask for it and you have watched them handle the step before it.
Nobody regrets going up slowly. Plenty of people regret the opposite. The full first ride plan is in how to teach a kid to ride.
How our bikes compare
| Bike | Top speed | Who it fits | Price |
|---|---|---|---|
| 50cc gas mini | 32 mph | About 5 to 13, up to 170 lbs | $300 |
| 60cc double exhaust | 35 mph | About 9 and up, up to 220 lbs | $380 |
| Sykeruns X5 electric | 50 mph | About 4 ft to 5 ft 11 in, up to 265 lbs | $975 |
| Sykeruns X7 electric | 56 mph | Up to about 6 ft 3 in and 330 lbs | $1,350 |
Note the gap between the 50cc and the 60cc is only 3 mph. If you are choosing between those two, speed is the wrong thing to choose on. Size is, and we laid that out in 50cc vs 60cc.
The electrics work differently: instead of a governor screw they have three selectable gears, so you lock a new rider in first and leave it there.
Questions
Can I make a 50cc faster?
You can open the governor fully, clean the filter, fix the chain and run fresh correctly mixed fuel. That gets you to what the bike was built to do. Beyond that people fit bigger carbs, different pipes and different sprockets, and that is where you start trading reliability and warranty for a few mph. We do not recommend it on a kid's bike.
Is 32 mph too fast for a child?
Wide open, for a beginner, yes. That is exactly what the governor screw is for. Set it low and raise it as they earn it.
Why does the seller's number not match what I see?
Rider weight and ground, nearly always. Quoted top speeds are measured with a light rider on flat hard ground. Also check that the governor is fully open before you decide the bike is slow.
Does a bigger engine always mean faster?
No. Our 60cc is 3 mph faster than our 50cc, not 20. What the bigger engine really buys you is pull off the bottom and the ability to carry a heavier rider.
How fast is 32 mph really?
About the speed of a car in a quiet residential street. On a bike with no doors, on dirt, it feels much faster than it sounds on paper. Helmet and gear every ride, no exceptions.
If you are shopping
Every bike we sell has an adjustable governor or selectable gears, so you control the top speed from day one.
Still picking? Our buying guide for parents walks through the whole choice, and the size guide settles which bike fits by height and age.
- 50cc gas minis in five colours, $300 shipped free
- 60cc double exhaust, $380 shipped free
- Electric for teens and adults, from $975
Not sure which one fits, text us at 623 320 8984 with the rider's height and weight. We answer the same day, and we will tell you to buy the cheaper bike when that is the right answer.
Off road use only. Not street legal and does not come with a title. Speeds are on flat ground with a light rider and will vary with weight, terrain and setup.