49cc Scooter dies during Idle

[hpratvfrk]

Hi all,

I bought a 49cc 4-stroke Vican Falcon XYQT50-6 (had ~4100KMs on it then) 2 weeks ago off Craigslist and there seems to be a big (or small) problem: upon a cold engine, it fails to idle in the first 5 minutes. It would run a few hundred metres, and as I come to a complete stop, the RPM doesn't stay at the 2,000 range and instead goes flat-out 0.

I have replaced the spark plug, motor oil (old oil was as dark as black coffee if not darker), and cleaned the air filter. I use 94 grade gasoline like the manufacturer and multiple forums suggested.

Here's the timeline of the problem:

It would take sometimes as much as 5 electric-starter presses to start the engine, and when I do, the engine dies as soon as I let go of the throttle after rolling 10 metres forward (this is done after ~4 minutes engine warmup). I would have to restart the engine, and I would run about 300 metres to my next closest Stop sign. It would die there. I would restart my engine, run for another 300 metres to the next Stop sign - and it would die there also. After this third time of dying on idle, it would be good to go, no more shutting down from then on. It's almost like a formula - it has to die 3 times in order to run smoothly. This is obviously not convenient and could be troublesome if this happens on a red light.

I also hear something slightly clinging and clanging (or the sound of something loose) in the CVT, where the kickstarter is, but I've tried to open up the cover with no luck (there's something that fastens of which I cannot see, after I unscrew all the obvious screws).

Can someone please help me out here? It's super frustrating especially when I've been trying to deal with this problem for a week!


Thank you!

[jnesss]

i hate when my bike doesn't start. here are the things i ran into, may not apply to you, but it's worth a shot

-old battery testing good and up to specs, but discharges way too fast (dead battery every damned morning)
-corrosion on battery terminals (can't start all the time)
-bad rectifier (running purely off the battery, almost stranded)
-i remember some days i'd have to rev the shit out of it til the engine's "warm" before it'd idle ok on it's own

[hpratvfrk]

Originally Posted by jnesss

i hate when my bike doesn't start. here are the things i ran into, may not apply to you, but it's worth a shot

-old battery testing good and up to specs, but discharges way too fast (dead battery every damned morning)
-corrosion on battery terminals (can't start all the time)
-bad rectifier (running purely off the battery, almost stranded)
-i remember some days i'd have to rev the shit out of it til the engine's "warm" before it'd idle ok on it's own

Thanks for your quick reply! Does my problem sound like your problem though? Did you manage to fix it? I'm guessing you replaced the whole battery?

let me know, please!

[jnesss]

i did a lot of testing with a volt meter on the battery.. try that? or search online to see if others have run into the same problems. when i'm stuck, i go straight to the gsxr forums lol.

[hpratvfrk]

Originally Posted by jnesss

i did a lot of testing with a volt meter on the battery.. try that? or search online to see if others have run into the same problems. when i'm stuck, i go straight to the gsxr forums lol.

Stupid question - do I have to charge scooter batteries before I use them (unlike cars where it's plug and play)?

[jnesss]

Originally Posted by hpratvfrk

Stupid question - do I have to charge scooter batteries before I use them (unlike cars where it's plug and play)?

u shouldn't. could be something wrong with the charging system? try to find a service manual online.

[Raid3n]

Originally Posted by jnesss

u shouldn't. could be something wrong with the charging system? try to find a service manual online.

he may mean new.

if you are talking about a new battery, yes it needs to be charged unless it says otherwise. if its one where you have to fill acid, it needs to be charged.

for the constant stalling.. almost sounds like either lack of fuel or lack of spark.

check the spark plug, maybe replace it if you haven't already.
check that the boot for the plug isn't cracked.
try to find instructions online for testing your ignition coil.

for fuel, it may not be pulling fuel from the tank fast enough, but then that would cause it to die while riding usually not idle...

check spark first, probably easiest and cheapest.

[Puck Luck]

I assume this is carbureted, is there a choke?

[hpratvfrk]

Originally Posted by Raid3n

he may mean new.

if you are talking about a new battery, yes it needs to be charged unless it says otherwise. if its one where you have to fill acid, it needs to be charged.

for the constant stalling.. almost sounds like either lack of fuel or lack of spark.

check the spark plug, maybe replace it if you haven't already.
check that the boot for the plug isn't cracked.
try to find instructions online for testing your ignition coil.

for fuel, it may not be pulling fuel from the tank fast enough, but then that would cause it to die while riding usually not idle...

check spark first, probably easiest and cheapest.

Thanks for this. Just a quick update:

I have replaced the spark plug, cleaned the air filter, replaced the motor oil (which was darker than black coffee), and even put some Sea Foam in the tank. The idle is slightly smoother because of the Sea Foam, but other than that, not much improvement.

What do you guys think?

[snails]

can u adjust your idle? problem is with a cold engine is that its very poor at burning up all the fuel until its up to opporating temp. this is why cars have an idle air control valve run off coolant.. it holds the rpm higher until the coolant reaches opporating temp, then the idle is brought down to a more fuel efficiant level.

adjust you idle a bit higher. and warm the thing up for a couple mins after starting it.

[hpratvfrk]

Originally Posted by snails

can u adjust your idle? problem is with a cold engine is that its very poor at burning up all the fuel until its up to opporating temp. this is why cars have an idle air control valve run off coolant.. it holds the rpm higher until the coolant reaches opporating temp, then the idle is brought down to a more fuel efficiant level.

adjust you idle a bit higher. and warm the thing up for a couple mins after starting it.

How do you adjust an idle?!

[Puck Luck]

Originally Posted by Puck Luck

I assume this is carbureted, is there a choke?

No choke on this scooter? Can't imagine there not being some sort of choke or enrichener for cold starts.

[hpratvfrk]

Originally Posted by Puck Luck

No choke on this scooter? Can't imagine there not being some sort of choke or enrichener for cold starts.

It's an auto-choke.

[Puck Luck]

Originally Posted by hpratvfrk

It's an auto-choke.

sounds like thats where the problem is

[hpratvfrk]

Originally Posted by Puck Luck

sounds like thats where the problem is

How do I fix it...?

[Puck Luck]

not really sure, likely will have to remove the carb to have a closer look

[hpratvfrk]

Originally Posted by Puck Luck

not really sure, likely will have to remove the carb to have a closer look

You know any local shops that would take a look at a Chinese scooter? I'd love to fix this asap, pretty inconvenient problem.

[Raid3n]

depends on how the autochoke works.. on cars i've mostly seen electronic autochoke.. but could just be a metal coil that expands when its warm and would release the choke.. but yea, teardown is the most likely result

[Phil@rise]

Its a fuel enrichment problem. most likely the choke. to be sure pull the plug if its black its running rich if its greyish white its running lean.

[underscore]

Have you tried revving the motor for about the amount of time it takes you to ride this ~600m before starting off?