Very Difficult To Start

[BillyGreen1973]

the fluid staining below the breather, indicates a fuel overflow, this could be due to an over rich mixture, or the vaccum slide is sticking open, or the needle is sticking open.

The vaccum slide is the black plastic tube that sits inside the carb, it has a hole in the bottom that the needle goes through.
Also check your needle isn't bent

[hypojam]

Baotian: My bike used to do what your describing Alot when it was winter last year.

What i did which did mostly fix my problem was to disconnect the auto-choke, therefore making the fuel mixture richer so the carb could cope with the very cold temps.

so try disconnecting the auto choke and go for a long ride again and see if it does it.

[hypojam]

hypojam said:

Baotian: My bike used to do what your describing Alot when it was winter last year.

What i did which did mostly fix my problem was to disconnect the auto-choke, therefore making the fuel mixture richer so the carb could cope with the very cold temps.

so try disconnecting the auto choke and go for a long ride again and see if it does it.

Just an idea for you to try, might work

[baotian]

yea will try that if all ells fails cheers, yes botanic that is also what my carb looks like, what is wrong with that,
and billy, so that stain is not normal and there needs to be something done about it.
ive cheked that the ruber seal is seated properly and the needle isent bent, and the washer on the needle is at the second from bottom

[Botanic]

If the hole in your carb is exactly like that, look really good, you have a problem. The picture is my old carb.
I had that carb fitted on my scooter when I bought it. I had the exact same problems as you describe. I read on the swedish forums and found out about the bad carb.
So I emaild the company that sold me the scooter and asked if it was possible that I have one of those carbs. I got back an answer that the hole should be round. The company that I bought my Baotian Sport from had specificly ordered the better carb for all their scooters.
After looking at my hole, I realized that I might have one of those bad carbs. I took that picture and sent the picture to the retailer. Three days later I got a new carb with a round hole in my mail. So I fitted this carb and all my problems disappeared.

One person claimed on the swedish forum that there is nothing wrong with the carb. The problem is that the main jet in these carbs are too small for some reason. I don't know about this. Somehow I trust the retailers version better. These carbs are crap.

Also, the diaphrams wear out quite quickly on these chinese scooters for some reason. Since almost all of the scooters atleast here in Sweden comes with the round version, it would probably be a nightmare to buy a new diaphram that fits the crappy carb.

Good luck!

[baotian]

no i now see tat it isent the same carb as mine, as mine is rounded at the bottom and not that funny shape.
can i ask you where you have placed your washer on ur ike on the carb pin?

[baotian]

ok i went to work on it again this morning (17 miles) and it was cold, and still had the problem, for some reason when the weather is cold the bike doesent rev as high when idle, which i think causes it to stall when i acelerate.
anyway when i had finished work it was not as cold as this morning by far, and the bike reved normal again when idle. and i didnt have the problem once, so it must be to do with the weather, i just dont know why anyone ells doesent get this prolem in the mornins?

[Botanic]

Cold air has more oxygen in it. This is usually what you would want. My guess is that you don't get enough fuel to go with all that oxygen. Or maybe you have very bad engine oil. (I assume that you have changed the crap (rubbish in brittish english, right?) that came with the scooter when you bought it.)
Here's some really good reading: www.4strokes.com/tech/4sjetting.pdf

BIKE WONT START WHEN COLD OUTSIDE
•Pilot jet too lean •Air filter over-0iled •Motor oil too thick for temperature

[baotian]

thats nice info, yes already done 2 oil changes with halfords 4 stroke fully synthetic.
and i have alterd with the fuel mixture....
so are you saying that these scooters perform better in cold weather!!??

[Botanic]

There are two sides on every coin...
You can get more from the engine when the air that is sucked into it is cold. This is if you have managed to get the fuel mixture right through the whole registry (You will probably need a bigger main jet to accomplish this).
Getting more fuel into any engine is usually not a problem. The problem is to get more air. So when the air is cold, it helps this problem.
On the other hand these engines are air cooled, and the fan blows with constant speed wheter the air surrounding the engine is 40 C or -10 C. This is where the problem with cold air comes in, in my opinion.
The engine will never reach it's working temperature if the fan is cooling the already cool engine.
This has not been a big problem for me yet. I have noticed that my engine goes too cold when it is below -5 C outside.

I have plans on using ductape to block half of the fan grill. I think this will be enough to not cool the engine too much during the winter.

[baotian]

ok i went to work on it today with 3 quaters of a tank, and the problem wasent that bad, it didnt keep staling when i acelerated fom stand still, altho it would do it sometimes.
and on the way home it was warmer then this mornign, and it did it raly badly, i alos noticed that there was only just under half a tank, so i decided to fill her up just for a try, as i thight for a second that it could be that theres not anoth presure in the fuel tank.
and to my suprise, it didnt do it once after refuling!?

now im not sure if its quensitence (how eva you spell it) or not, but im going to see how it runs tomorow untill it gets to under half a tank.

what do you guys think, could it be a fuel pump problem?

[Macrofeet]

One more item to try is check your air intake pipe is not kinked

Question stupid i know

Has your bike left out in the rain frost much with no cover

if this is the case which it probably is not drying it out and buying a cover will help

[baotian]

nope, its allways kept in a garage over night, and has been left out in the rain ONCE but it was happening beofre that so isent hat, and have cheked for kinks in the air intake

[Macrofeet]

I am interested by

I have plans on using ductape to block half of the fan grill. I think this will be enough to not cool the engine too much during the winter.

i am wondering if fitting a temp sensor/switch to slow the fan while the engine warms might be possible

[Botanic]

macrofeet said:

I am interested by

I have plans on using ductape to block half of the fan grill. I think this will be enough to not cool the engine too much during the winter.

i am wondering if fitting a temp sensor/switch to slow the fan while the engine warms might be possible

This is not possible. The fan is completely mechanical. The fan spins the same speed as the engine.

The only way to get around this is to replace the fan with an electrical one. Which is not worth it in my opinion.

[Macrofeet]

Ahh right, ty

[Macrofeet]

is computer freak assume everything is electrical ;D

mechanical

[gembo]

--------------------------------------------------------------------------------
Hi i have a yiying 50QT (4 stroke) 4 my 16th bday, the first couple of weeks it was fine no problems but all of a sudden i got probs starting it as wen i turn it on and rev my scoota howeva wen i leave my scoota on tick ova it cuts out on me.it also does this wen i stop at junctions and stuff. my dad thought it could be fuel starvation,he has took the carb off and checked the needle and everything is clean, any ideas on wot else it could b??? #crying#