A choke, sometimes called a choke valve or choke cable is intended to constrict airflow in the carburetor of an engine – in this case, a motorcycle engine. The purpose of using a choke is to help with cold weather starts or for when the motorcycle has been sitting unused for an extended period.
Using a choke appropriately enriches the fuel-air mixture and gets the rider off and running properly. It helps extend your engine life too. In this post we’ll tell you the 7 things you need to know about a motorcycle choke.
Most of us want to just hop on, turn the key and hit the open road at full-throttle. Now, with modern, fuel-injected machines that’s usually par for the course.
But what if you’re a devotee of classic iron? You probably know what it feels like hitting a flat spot in the midst of an acceleration because you didn’t properly warm your motor up. That can be annoying but also dangerous. It’s a potential hazard that can easily be avoided.
Today, we’ll answer the 7 most commonly asked questions about motorcycle chokes. Let’s get to it!
Can You Ride A Motorcycle With The Choke On?
Finish your coffee, survey the day, check the tire pressure whilst warming your motor, but don’t ride with the choke on.
If you ride with the choke engaged the enriched fuel/air mixture will start to carburize your spark plugs and hamper proper ignition.
If you find your motor will only run with the choke switched on then your fuel delivery system (carburetor, or spark plugs) need to be checked and probably cleaned. Either that, or you’re running poor quality fuel.
Bear in mind that a proper fuel/air ratio for an ICE is 14 parts air to 1 part fuel. Choking an engine increases the fuel aspect of that ratio and thus lowers combustion efficiency whilst cranking up engine heat. Not good!
Using an exhaust gas analyzer is a good way to check your fuel/air numbers. That aside, if you’re counting on your choke too much it means you may need a trusted mechanic to give your engine a thorough once over.
How Long Should You Leave A Motorcycle Choke On?
You should only have the choke on for a short spell, whilst the engine is warming up.
Remember, the purpose of the choke is to facilitate engine starts in cold weather or perhaps after the bike has been parked for an extended period.
The choke should not be used in order to keep an otherwise warmed motor running.
If a choke was meant to be engaged all the time, manufacturers wouldn’t have enabled an “off” position.
In short, leave the choke on as long as necessary, but once the motor is warmed and is idling well there is no need to keep the choke on.
When Should You Use The Choke On A Motorcycle?
The choke on a motorcycle is part of the carburetor and it functions to enrich the fuel/air mixture in order to facilitate cold starts, either when the weather is chilly or when the engine hasn’t been turned over for an extended time.
When an engine is cold it doesn’t vaporize fuel efficiently, resulting in rough idling and stalling.
The choke should be used to “choke” the flow of air and allow for a richer fuel mixture.
Only use the choke when starting your engine under cold conditions. Once you’re up and running smoothly turn it off.
Related: Motorcycle Shuts Off When Clutch is Pressed or Released? (14 Causes)
What Happens If You Leave The Choke On Overnight?
Nothing will happen if you leave the choke on overnight. Since the engine is off, the carburetor isn’t in operation and nothing is moving internally in the engine no harm will come.
However, if you’ve shut the bike down after a ride and you find the next day that your choke is in the on position that means you’ve been running the engine with the choke engaged. Not the end of the world, but best to switch it off.
Get in the habit of switching the choke off once your engine is running smoothly, that way you won’t park the bike overnight with the choke engaged. Off at night. On at light…at least until the engine is purring, then turn the choke off.
Is There A Choke On A Fuel-Injected Motorcycle?
Motorcycles that feature EFI (Electronic Fuel Injection) don’t have carburetors and so, don’t use a choke valve to modulate the fuel/air mixture.
Instead, EFI is a computerized system that takes into account air temperature, air pressure and all other relevant data (stuff you might not even think of) to ensure the motor gets the optimum fuel/air ratio in order to start and then run smoothly.
Since the EFI “brain” is handling all of this there is no need for a choke on a fuel-injected motorcycle. However, EFI bikes do feature a fast idle lever. It should only be used when starting from dead cold, and only then if the bike is rough idling.
After the engine is turning over well, flip the lever off. Don’t run an EFI bike with the fast idle lever on.
Why Does My Bike Die When The Choke Is Off?
If you find that your bike is cutting out after you’ve turned the choke off it most likely means that you aren’t getting enough fuel into the motor.
This can be caused by dirty or clogged pilot jets, dirt clogging the fuel line, a clogged fuel filter, a fouled petcock or vacuum issues with the carburetor(s).
If you’re having this problem the cause is usually clogged pilot jets.These jets provide fuel to the carbs at idle and during the first acceleration.
If you roll on the throttle and the engine dies it most likely means the pilot jets are clogged and even a slight blockage can prevent fuel from getting into the carbs to keep a steady idle or to accelerate.
Blasting the choke to blow fuel into the carbs will solve your idle problem but it isn’t a long-term solution as the fuel mixture is too rich, the engine will over-rev and normal riding isn’t possible.
How To Fix?
Start with a simple carb cleaner to clear the jets. If that doesn’t work, you’re going to have to get down and dirty or take it to your mechanic for a possible carburetor rebuild. We will cover carburetor rebuilds in an upcoming article.
Hint: A carburetor rebuild kit isn’t expensive and once you learn how to do it, you’ll save lots of money on any future repairs.
How Do I Best Warm My Bike Engine On A Cold Morning?
For a carbureted bike it’s simple. Kick it over with the choke on and let it idle. After about 10 seconds the oil will have had a chance to circulate.
Flip the throttle a bit. If the engine sputters, that means it’s still cold. Let it idle a bit more, another 5-10 seconds. If the engine revs up and then settles down to a nice idle you should be good to go. Put it in gear and take off.
Once underway back off the choke a little and see how the engine responds. After about 2 or 3 miles turn the choke off completely. Don’t put the hammer down until you’ve turned the choke off completely.
On the other hand if you’re riding a newer, EFI machine, you’ll not need to go through any of this. A modern fuel management system will ensure that you have the right fuel/air mix from the get go-that’s why these bikes don’t have a choke.
A new bike needs only seconds, not minutes, to warm up, and after the first 1,000km you can basically push the starter and go. In fact, over-warming a newer bike can actually do more harm than good.
For older machines use the choke and follow the advice above and you and your bike will have many memorable years together.
That’s it. Enjoy your ride!
There you have it, 7 things you need to know about motorcycle chokes. Just keep in mind that a choke is used to help warm a carbureted engine, especially in cold conditions or when the bike has sat neglected for a spell.
Riding with the choke on isn’t the worst thing in the world but can cut your fuel efficiency and may result in some minor problems that are easily avoided.