The short answer
The thing that kills a small 2-stroke over winter is fuel left sitting in the carburetor. It evaporates and leaves a varnish that blocks jets you cannot see. Drain the carb, and you have solved eighty percent of spring starting problems before they happen.
The whole routine takes about half an hour and saves you a carburetor rebuild in March.
The winter storage routine
1. Drain the carburetor
This is the one that actually matters, so do it even if you skip everything else.
Find the fuel petcock on the tank and turn it off. Then start the engine and let it run until it dies on its own. That burns off what is in the float bowl. If there is a drain screw on the bottom of the bowl, back it off as well and let the last of it out into a rag.
Premixed 2-stroke fuel goes off faster than straight gas because the oil separates out. A bowl of it left from October is a gummed jet by April.
2. Deal with the tank
Two valid approaches. Either drain the tank completely and leave it dry, or fill it nearly full with fresh mix and add fuel stabiliser. What you must not do is leave it a quarter full, because the air space condenses moisture and rusts a steel tank from the inside.
For a small bike stored in a garage, draining is simpler and there is less to go wrong.
3. Fog the cylinder
Pull the spark plug, squirt a small amount of 2-stroke oil or fogging oil into the plug hole, then pull the starter slowly two or three times to spread it around the cylinder wall. Put the plug back in loosely.
This leaves a film of oil on the bore so it does not surface-rust over a damp winter.
4. Clean it, actually clean it
Wash off the dirt and dry it properly. Mud left on a frame holds moisture against paint and metal for four months. It is the difference between the bike looking used and looking neglected when you go to sell it.
Clean and re-oil the air filter while you are at it, so it is ready in spring.
5. Chain and cables
Clean the chain and lube it more heavily than usual. Put a little oil at the ends of the brake and throttle cables. See chain maintenance.
6. Get the tyres off the ground
If you can, put the bike on a stand or a crate so the tyres are not carrying weight all winter. If you cannot, inflate them to full pressure and roll the bike a few inches every month or so to change the contact patch.
7. Where you put it
Somewhere dry and out of the sun. UV wrecks plastics and seats faster than anything else. Cover it with a breathable cover or an old sheet rather than a plastic tarp, because a tarp traps condensation underneath and that is worse than no cover at all.
8. If it has a battery
Most kick or pull-start 50cc minis do not. If yours has a battery, or if you are storing an electric bike, disconnect it and store it indoors at room temperature, charged to somewhere around half to sixty percent. Not full, not flat. Top it up every couple of months. There is more on pack care in how to charge an electric dirt bike battery.
Waking it up in spring
- Mix fresh fuel. Do not use last year's. 25 to 1, 5.12 oz per gallon. Full chart here.
- Pull the plug and check it. If you fogged it, it will be oily. Clean or replace it. How to read a plug.
- Turn the engine over a few times with the plug out to clear the fogging oil, then fit the plug.
- Check tyre pressures and chain tension. Both will have changed.
- Squeeze both brakes and confirm they bite before anyone rides.
- Go around every bolt with a wrench. Same as you did on day one.
- Start it with choke on and expect it to take a few more pulls than usual. Let it warm gently before the first ride.
If it won't start in spring
Nine times out of ten it is the carburetor, and it is because fuel was left in it. The jets are blocked with varnish and the bike will pop and die, or run only on choke. The fix is to pull the float bowl and clean the jets with carb cleaner and compressed air. A rebuild kit for these carbs is inexpensive. That exact symptom is covered here: dirt bike starts then dies.
Work through the wont start checklist before assuming the worst, because it is often something simpler like a fouled plug or the tether pin sitting out.
Questions
How long can I leave premix in the bike?
Treat about 30 days as the limit for mixed fuel sitting in a carburetor. Longer than that and you are gambling. Mix only what you will use.
Do I need to do all this in a warm climate?
If the bike is going to sit unused for more than a month, yes, at least drain the carb. In Arizona you can ride most of the year, so this matters more for the mid-summer break than for winter, but the fuel does not care which season it is.
Should I start it once a month over winter?
Only if you run it long enough to fully warm up, ten to fifteen minutes of actual riding. A brief start in the driveway is worse than nothing: it pulls fresh fuel into the carb, coats the cylinder with condensation, and never gets hot enough to burn it off.
Can I store it outside?
You can, but expect faded plastics, a rusty chain, and a rotten seat. If it must live outside, get it off the ground and use a breathable cover.
Maintenance walkthroughs at manual.pluggedby50cc.com, or text 623 320 8984.
Plugged by 50CC is an independent retailer. We do not manufacture, assemble, modify or service the bikes we sell. Every bike ships sealed in its factory crate exactly as it reaches us, about 90% assembled from the factory, and final assembly and setup are completed by the buyer. Off-road use only. Riders under 18 should always be supervised by an adult.