Could someone please explain choke?

I am a motorcycle newbie; I got my license and Ninja 250 in July. On top of that, I am a total newbie when it comes to anything mechanical. I do plan on learning and my goal is to eventually learn how to fix my own bike, but right now I'm having one minor problem:

I don't know what choke is and why it is/isn't good/bad.

I have been having a problem with stalling at the first couple of stoplights when I first start riding. I've been told that I'm using too much/not enough choke.

Here's what I do when I first try to start the bike:

1. Try to start the bike without using any choke.
2. If it doesn't start, I bring the choke lever to the halfway point (where the choke actually starts) and start the bike.
3. I will keep the RPM's below 2k while it's warming up and take off after about 2 minutes.
4. Bike will usually stall at first stop light.
5. Open choke a little more and start bike up. I close the choke at the next stop light, which is about 7 blocks from my apartment.

My manual says that I should turn the choke lever all the way up (but this sends the RPM's screaming!) if it's a cold day and to keep it under 2.5k RPM. It also says to continue to back off the choke until the bike can idle on it's own and to not let the bike warm up for more than 5 minutes. But this doesn't really help either. I will try to open the throttle, while stopped, to get the RPM's up, but it shuts off if it's still cold.

My questions are:

1. What am I doing wrong?
2. If I get to the stop light and the choke isn't engaged, I will try to rev the rpm's by opening the throttle a little, but it will instead shut off. Is this a potential problem?
3. Some of my friends say that I should let the bike warm up for at least 5 minutes, and other's say I shouldn't let it warm up more than a minute. Who is right?

Note: once the bike gets going pretty good there aren't any problems.

Thanks in advance for any help.

I'll take a shot at it, and the other guys/gals on the forum can add things I've missed. When I had a bike with a choke, after it was warm, I didn't require choking the engine at all to make it run properly. I'm also surprised that it takes more than two minutes to warm up your bike in order for you to ride without the choke. It could be only a minor adjustment to your carb to adjust how lean or rich it's set at. I don't remember if that's a gravity feed fuel system, or you have a fuel pump. If it's a gravity feed, it could be a fuel stoppage somewhere between your tank and your carb. If it has a fuel pump, it might be a weak fuel pump, and it's not pumping enough fuel when you first start off. Not sure! But, if it were either of those two things, one could assume that it wouldn't run properly any time! The puzzling part is that when it warms up more, it runs fine. ????

After you let it warm up for two minutes, do you turn off the choke entirely before you start out? If you leave it at half choke, it's possible that by the time you get to your first stop, the carb has logged up with fuel. Then, when you take off again, all that fuel is dumped into the cylinder, and it chokes itself out. If you run the starter longer than usual, it might be leaning out before it starts, in spite of your having to choke it again.

But then again, if you've tried to shut off the choke entirely, and it still stalls out til it warms up more, it might just be the nature of the beast, even tho I've had two with chokes, and neither of them had that problem.

I might have merely confused you - hope someone else is more helpful.

After rereading your post, your item No 2 makes me think the carb is set too lean. Since you have no mechanical experience, I might suggest you take it to a dealer and ask their mechanic to set the carb for you so it doesn't do that anymore. That would be the easiest for you.

You need more fuel to start a cold engine rather than a hot one. Thats what the choke is for, it cuts down on the amount of air that enters the engine. Most things people call chokes on a motorcycle is really an enrichener (as it doesn't cut off air to the engine but gives it extra fuel through a seperate passage) but we won't get into that.

When the engine is dead cold like it sat overnight or for like 8 hours or so use the choke to get it started. When the engine has trouble starting without the choke but has been ran that day use the choke but about half way or more.

2. If I get to the stop light and the choke isn't engaged, I will try to rev the rpm's by opening the throttle a little, but it will instead shut off. Is this a potential problem?

Is the bike warm at the time or still cold? Almost all bikes are slightly on the lean side from the factory. You may have to bump the idle up some. I dont know the year or condition of the bike so I don't know if you might need carb work or not.

3. Some of my friends say that I should let the bike warm up for at least 5 minutes, and other's say I shouldn't let it warm up more than a minute. Who is right?


Every bike is different. When it's warmed up enough to ride is when you can take the choke off and it will idle on its own and rev without stalling.

After you let it warm up for two minutes, do you turn off the choke entirely before you start out?

I've tried both. After the bike can idle on it's own, I turn the choke off, let it warm up for a couple of minutes and take off, but usually the bike cuts off. I've also let the bike warm up, with the choke on, for about 2 minutes and take off. The first light is about 2 blocks from my apartment and I close the choke there, and that's when the bike cuts off.

Is the bike warm at the time or still cold? Almost all bikes are slightly on the lean side from the factory. You may have to bump the idle up some. I dont know the year or condition of the bike so I don't know if you might need carb work or not.

I'm guessing that the bike is still cold despite warming up for a few minutes. The other day I noticed that the bike was idling at 2k RPM after it was warmed up, so when I got home, I adjusted the idle by turning the idle adjustment screw. The manual says to set it around 1.5k RPM, which is where I set it at. Is that what you mean by "bump the idle some?"

No I meant turn the idle up as in bump it up some but if the bike isnt fully warmed it doesn't really do any good to turn it up. My 500 takes a good 3-4 minutes to warm up and even then it's not fully warmed up.

My Yamaha acted similarly, the trick was to start it and let it warm up a few minutes on full choke, move to half choke for a little longer, and then it would be OK. I could drive it on half choke if need be. You just need to figure out how long the choke needs to be on before the bike runs well without it and then just do it that way all the time. It's perfectly normal on a carb'ed bike.

The only thing he did not mention is that driving with the Choke ON can damage your MC, causing premature fouling of the spark plugs at a minimum!

The choke is meant to be a starting aid only and only when the engine is cold. Should normally not have to use it when starting a warm engine. Your MC may just be a cold blooded, tempermental gal when cold. Just like a woman, you gotta take your time to warm her up, then she'll do everything you ask of her. Your warm up may just take longer. Warm up is important to long engine life too!

Listen to CB750! Have your current plugs checked you may have already fouled them.

Ride safe & long,
Colorado fats

Fouling is far less of an issue than it used to be, they've got these newer bikes so leaned out for the emissions that it's rare to foul a plug. But CO and CB are right, you don't want to leave it on any longer than necessary, but you do need to experiment and find out what is right for your bike. All bikes are different, my Yamaha wasn't worth a crap until it was fully warmed up, the Harley is ready to go as soon as you start it.

I am a motorcycle newbie; I got my license and Ninja 250 in July. On top of that, I am a total newbie when it comes to anything mechanical. I do plan on learning and my goal is to eventually learn how to fix my own bike, but right now I'm having one minor problem:

I don't know what choke is and why it is/isn't good/bad.

I have been having a problem with stalling at the first couple of stoplights when I first start riding. I've been told that I'm using too much/not enough choke.

Here's what I do when I first try to start the bike:

1. Try to start the bike without using any choke.
2. If it doesn't start, I bring the choke lever to the halfway point (where the choke actually starts) and start the bike.
3. I will keep the RPM's below 2k while it's warming up and take off after about 2 minutes.
4. Bike will usually stall at first stop light.
5. Open choke a little more and start bike up. I close the choke at the next stop light, which is about 7 blocks from my apartment.

My manual says that I should turn the choke lever all the way up (but this sends the RPM's screaming!) if it's a cold day and to keep it under 2.5k RPM. It also says to continue to back off the choke until the bike can idle on it's own and to not let the bike warm up for more than 5 minutes. But this doesn't really help either. I will try to open the throttle, while stopped, to get the RPM's up, but it shuts off if it's still cold.

My questions are:

1. What am I doing wrong?
2. If I get to the stop light and the choke isn't engaged, I will try to rev the rpm's by opening the throttle a little, but it will instead shut off. Is this a potential problem?
3. Some of my friends say that I should let the bike warm up for at least 5 minutes, and other's say I shouldn't let it warm up more than a minute. Who is right?

Note: once the bike gets going pretty good there aren't any problems.

Thanks in advance for any help.

How many miles are on it? If I were to guess, I'd say you have the wrong heat range plugs in it.