My bike catch a cold

[tancy]

Hi all,

i riding a TA150 and every morning when i kick start my bike, the engine is sure to die off. So i will need to push up the choke for around 5 sec for the bike to warm up . After that the bike will be in gd condition, ready to move off and ride.

Any idea what's wrong with the bike?

[redbeacon]

Simple. Combustion is difficult when your bike (specifically, the environment in your engine) is cold.

 

To compensate for the cold morning temperatures, a richer fuel mixture is needed and to do that, the choke is used temporarily with the kick-starting procedure.

[tancy]

Any ways to cure this illness?

[PinKcHicK]

i tink most bikes need warm-up before they move off from resting in the cold nite especially rainy days like this.. say maybe a few mins?

 

even cars do.

i have the same problem with my scoot at times.

its a norm, dun worry, not an illness....

[deckard]

if you do it long enough, will there be any problems with the choke??

[nebulaz]

choke is there for a reason..hehe..just use la..dun wory..

[Refugee]

the choke is already the 'cure' for your bike's 'cold'

 

you already applied the correct stuffs...

[Zai TZM]

it's normal for most bikes in the morning.. no worries..

[tancy]

icic. so even if send for servicing or repair, the mechanic also cant do much.

[redbeacon]

if you do it long enough, will there be any problems with the choke??

The choke system consists of a simple lever, and a cable that leads from it to the carburetor (for non-Fuel Injected [FI] bikes).

There is no need to worry about mechanically "spoiling" the choke system...unless you delibrately cut the cable (alright, so that's a weird and crude scenario...)

 

It's been a long time since I have been taught how the carb works by a mechanics school, so I've did some research for the benefit for all of us "carb" bike people and have paraphrased this explanation:

 

The Choke System

(for carburetor based bikes)

 

The choke system is used to start cold engines.

 

During the starting sequence, air and fuel (aka petrol) gets "sprayed" into your carburetor and rushes into your engine, much like how a vacuum cleaner sucks dust.

 

When your engine is cold, this phenomenon happens: some of that air/fuel mixture that gets into your engine somehow condenses and sticks to the walls of your engine (cylinder walls).

 

It shouldn't be doing that. In an ideal environment, that mixture should float around in a gaseous state, and wait for the spark plug to ignite it (during one of the engine stroke sequence), starting the engine in turn and getting it moving.

 

So, with most of that mixture condensing on your walls of your engine, so little mixture remains floating. How can that engine ever start with so little mixture (lean) when most of it has gone onto the walls of your engine?

 

The purpose of the Choke, when operated, is to add more fuel to the engine to compensate for the wasted fuel that is stuck to the cylinder walls.

 

Once the engine is warmed up, condensation is not a problem, and the choke is not needed.

[redbeacon]

icic. so even if send for servicing or repair, the mechanic also cant do much.

You have to be most concerned about the ability of your bike to operate as smoothly when on the road (i.e.) adding the throttle does not bog down your bike or make it sluggish.

 

Don't worry too much on the bike starting sequence -- unless there's an electrical problem or that the battery is failing....those are other problems that I'm not going to elaborate since this is a "My bike catch a cold" thread.

[redbeacon]

even cars do.

i have the same problem with my scoot at times.

its a norm, dun worry, not an illness....

 

You'd be surprised that cars (and most Class 2 bikes) uses a Fuel-Injected (FI) system where a computer senses how cold the engine is, and automatically sprays in more fuel. This is what I call "Automatic Choke" which is "hands-free".

 

You just need press the electric-start and let the bike do its job. Fwah!

 

EDITOR'S NOTE: FI systems does more than just "auto-choke". Fuel management as well.

[PinKcHicK]

You'd be surprised that cars (and most Class 2 bikes) uses a Fuel-Injected (FI) system where a computer senses how cold the engine is, and automatically sprays in more fuel. This is what I call "Automatic Choke" which is "hands-free".

 

You just need press the electric-start and let the bike do its job. Fwah!

 

truly very tech-y of u..

[Refugee]

You'd be surprised that cars (and most Class 2 bikes) uses a Fuel-Injected (FI) system where a computer senses how cold the engine is, and automatically sprays in more fuel. This is what I call "Automatic Choke" which is "hands-free".

 

You just need press the electric-start and let the bike do its job. Fwah!

 

auto choke and EFI isnt the same right?

 

cos my carb bike has auto choke... but its carb operated...

[redbeacon]

auto choke and EFI isnt the same right?

 

cos my carb bike has auto choke... but its carb operated...

Hmm...if yours have auto-choke, then I must have not been keeping up with technological advances with carb bikes...

 

Auto-choke system on a carb bike...now that's interesting! What bike?

[Refugee]

just a humble vespa gt200.. haha

[contrarian]

Hmm...if yours have auto-choke, then I must have not been keeping up with technological advances with carb bikes...

 

Auto-choke system on a carb bike...now that's interesting! What bike?

 

Carburettor scooters with the Piaggio LEADER engine like the Aprilia Atlantic work with an automatic choke.

[arthur_chan]

want to ask is choke like opening throttor?

[redbeacon]

I don't think so.

 

The choke system injects in an even more fuel quantity per basic volume of air at that throttle position (which is 0% throttle, duh!)

 

"Opening throttle" makes the system inject in more fuel, *and* air.

 

 

P.S.: For the sake of illustrating how engines work (and the fact that I am suffering from temporary writer's fatigue at 1.50a.m. in the morning), I decided to use the work "inject". Sorry ah. If any one of you wanna correct me, please do so. Thanks!

[kito]

I don't think so.

 

The choke system injects in an even more fuel quantity per basic volume of air at that throttle position (which is 0% throttle, duh!)

 

"Opening throttle" makes the system inject in more fuel, *and* air.

 

 

P.S.: For the sake of illustrating how engines work (and the fact that I am suffering from temporary writer's fatigue at 1.50a.m. in the morning), I decided to use the work "inject". Sorry ah. If any one of you wanna correct me, please do so. Thanks!

 

"Inject" is a fine word to go with your explanation..

[Sky99]

eject?!!!!

[arthur_chan]

I don't think so.

 

The choke system injects in an even more fuel quantity per basic volume of air at that throttle position (which is 0% throttle, duh!)

 

"Opening throttle" makes the system inject in more fuel, *and* air.

 

 

P.S.: For the sake of illustrating how engines work (and the fact that I am suffering from temporary writer's fatigue at 1.50a.m. in the morning), I decided to use the work "inject". Sorry ah. If any one of you wanna correct me, please do so. Thanks!

 

so for cold engine can just open throttle? or use choke better?

[Constructicon]

deh...already explained man.

Use the choke.

[Silent Hunter]

Interesting read.

 

If the choke works by injecting more fuel, and if we remove the air filter all together, wouldn't this allow extra air and extra fuel into the engine resulting in extra power???

 

Will this allow the TA200 to go beyond 150km/hr ???

 

Kee! Kee! Tried riding around the carpark without any filter for about 2 minute when I washed & dried my air filter last week.

Result: Felt like no power, like fuel tank running on empty, most likely because too much air not enough fuel.

 

Didn't know the choke works like this, otherwise might have gotten a high FC but super powered ride last week by opening the choke.

[redbeacon]

Interesting read.

 

If the choke works by injecting more fuel, and if we remove the air filter all together, wouldn't this allow extra air and extra fuel into the engine resulting in extra power???

Welcome to the world of fuel-air ratio and stoichiometry

 

This study is where car and motorcycle engine engineers usually construct and tune engines to make sure their ratio of the incoming mixture (air : petrol) is just right for the engine to properly combust that mixture.

 

Terms

Air-fuel ratio: the ratio of air and petrol that remain in the engine after both are being sucked in.

Stoichometric mixture: the ideal air-fuel ratio (limit) that will definitely combust efficiently. i.e.: Not-too-lean and not-too-rich, but a "just right" mixture

 

Kee! Kee! Tried riding around the carpark without any filter for about 2 minute when I washed & dried my air filter last week.

Result: Felt like no power, like fuel tank running on empty, most likely because too much air not enough fuel.

 

So was there any engine knocking, slight moments of lag leading to jerking, or that opening throttle didn't feel as smooth as before?

Engines that run lean act that way.

 

FYI: The removal of the air filter for performance purposes (not recommended) is one of the good ways to mess up the stoichometric ratio. There are ways to compensate this, but at the expense of wasting too much petrol -- our bike engineers already made the perfect fuel-friendly bike, so why modify it? That is, unless you like to tweak your engines for performance, much like how a computer geek likes to overclock his computer to make it run faster.

 

FYI #2: Unless you are the engine engineers yourself or you have the real stoichometric values, engine tuning and jetting is usually done by "feeling the bike" when you ride. Silent Hunter, you've already demonstrated to us how you were "feeling" your bike and even gave us the results in the end too.

 

This is why you see a lot of bike mechs, who usually want to provide their customers faster service, "tune" your engine by twisting the air screw found on your carburetor and revving the engine to hear any abnormal sound.

Usually, the most accurate way to "do engine tuning" is to give the mech some time to figure out the abnomalities, then to adjust the air intake (via the air screw) and to upgrade/downgrade your jet needle(s) sizes if needed. After which, a test ride is done to see whether the bike runs fine.

 

** I'm not sure how mechanics deal with Fuel Injected (FI) bikes like most new and smarter Class 2 bikes and some others since they are carburetor-less and the direct petrol injection into the engine itself is controlled by a computer. Anyone care to share some insight on this?