Stalling half way through warming up By indiana (Read 2,608 times)

[indiana]

I have a YY250T scooter w 157 linhai engine I had a problem stalling at stop signs so I adjusted the timing top and bottom and that problem went away, but I still have a stalling problem before it's fully warmed up. If I don't sit on it and rev it at a certain point it stalls before it's fully warmed up, but when it's fully warmed up it runs fine. I tried adjusting the idle and that does nothing for the problem, but makes it idle too high once it's fully warmed up. So WTFrig? I have 250 miles on it. I don't see an air flow adjustment on the bottom either I see something that looks like a round solid post where that should be and a brass plug right behind it.

[Alleyoop]

You probably just need to adjust the Fuel Ratio Mixture a little Richer, now that the Temps are dropping.
Here is what your carb most likely looks like and I have labled where the FUEL RATIO MIXTURE is and when brand new they usually have a plastic cap on them which you have to take off to get at the screw.
Alleyoop

The Left Side of Carb:


The Right Side of Carb--NOTICE where the FUEL RATIO MIXTURE IS IN FRONT UNDERNEATH THE INTAKE SIDE :


AND HERE IS HOW TO ADJUST THE FUEL RATIO MIXTURE:

First Start up the Scoot and let it warm up At Least 5 minutes so the ENRICHER cuts off the Extra Fuel.

YOU WANT TO GET THE HIGHEST IDLE OUT OF THE FUEL RATIO MIXTURE:
So from where it is currently set FIRST TRY richening it up more:

1. Turn it 1/4 turn Counter Clockwise and wait about 10 seconds to allow the motor to catch up with the new setting. LISTEN or look at your tach:
a. If the IDLE GOES UP REPEAT #1, UNTIL the IDLE does not change or drops a little THEN TURN THE SCREW CLOCKWISE 1/8 and that should be the highest IDLE from the Fuel Ratio Mixture and go to #3.

**** IF ON THE FIRST 1/4 TURN COUNTER CLOCKWISE THE IDLE GOES DOWN OR DOES NOTHING, TURN IT CLOCKWISE 1/4 TURN TO GET IT BACK TO WHERE IT WAS AND GO TO #2****

2. Turn it 1/4 turn Clockwise and wait about 10 seconds to allow the motor to catch up with the new setting. LISTEN or look at your tach:
a. If the IDLE GOES UP REPEAT #2, UNTIL the IDLE does not change or drops a little THEN TURN THE SCREW COUNTER CLOCKWISE 1/8 and that should be the highest IDLE from the Fuel Ratio Mixture and go to #3.

3. If the idle is TO HIGH NOW LOWER the IDLE USING the IDLE SPEED SCREW so that your REAR WHEEL JUST WANTS TO TURN... Go to #4.

4. Now give the Throttle a quick twist and let go, the Motor should Rev up nice with no sputtering or hesitation and come back down to where you set the idle.

*** IF TURNING THE FUEL RATIO SCREW Clockwise or Counter Clockwise DOES NOTHING Then the Pilot Jet AND OR ITS PASSAGE ARE Clogged and you will have to clean the Jet and CLEAR OUT THE PASSAGE. And go through the Procedure again***

[indiana]

I see what you mean, I can barely get my hand in there or tell if it has a cap over it or if it's solid metal. I feel no screw there, so it must be covered (hopefully), What is the easiest way to access it do I have to remove a panel? and should I turn clockwise or counter clockwise after I mark my reference point? Thanks for your help!..

[Alleyoop]

You want to turn it COUNTER CLOCKWISE to RICHEN the Mixture CLOCKWISE TO LEAN IT.
FIRST TRY RICHEN it though from where it is set at.

As for getting at the screw some loosen the clamps holding the carb and rotate it just enough to get at the screw then give the screw a 1/4 turn rotate it back tighten the clamps and try it. Others if they can get there hand under it a small screwdriver HEAD and turn it with that(IF YOU CAN GET your fingers under it.
Alleyoop

[bhinch]

You said that the valves have been adjusted..... .004 intake and .006 exhaust... the enricher may not be adding enough fuel to keep the engine running when cold....you should check the enricher.. when cold the enrichers plunger is retracted and when warmed up it is extended to shut off the fuel for idle....I installed a manual choke system on my scoot and did away with the enricher all together...works great......should idle around 1800 to 2000 rpms..enjoy the ride....

[indiana]

Is it possible the autochoke is extending and going lean too early, or could this possibly be the lower octane fuel I use?

[Alleyoop]

Well easy enough to check your ENRICHER, just take it off LEAVE IT PLUGGED IN and lay it on its side. Hold your thumb over the hole start it and watch the ENRICHER and time it. It should Start to EXTEND out within 2 or so minutes and fully be extended out anywhere 3-4 minutes.

Now holding your thumb over the hole is just as if the ENRICHER IS working when cold.
Alleyoop

[Alleyoop]

As far as the OCTANE NO, high octane is for high compression engines, ACTUALLY it burns slower than lower octane for the high compression engines. So lower octane burns quicker and 87-89 is just fine.
Alleyoop

[indiana]

Awesome tips, I adjusted the air fuel ratio to no avail it still acts the same. Now to make sure I have the en-richer installed right. There is a slot for the o-ring then another slot right above the o-ring then a shoulder above that. If I put the mounting bracket in the slot above the o-ring the en-richer is wobbly and loose I don't think it's sealing. So I push it all the way in and clamp it over the highest shoulder and it seems to seal well. I can't find any clear images of where the mounting clamp goes so I am guessing...

[indiana]

Does the hold down clamp go in the slot at # 2 or over the shoulder at # 1 ?

Attachments:

[Alleyoop]

It is usually #2 the slot above the O-Ring. But your Enircher System may be a little longer and the #1 may work.

Did you check out the ENRICHER from the picture that is RETRACTED and after 3-4 minutes it should extend out around 1/4 of an inch. Now it could be putting the HOLD DOWN "C" clamp on #1 that it is to far in and blocking the hole and may be your problem.

So try it on #1 and then try it on #2 and see if it makes a difference.
Alleyoop

[kz1000st]

I would just add Seafoam to the gas. If you did the valve adjustment that leaves fuel flow. Your stalling problem seems to correspond with the time the choke closes and the bike starts to depend on the idle jet. A tiny amount of varnish or dirt would keep it from running properly while it still needs a lot of fuel.

[indiana]

It's starting to make sense. It's down in far clamping on the top shoulder so it may be prematurely leaning out. If I pull it out and clamp it to the # 2 shoulder it seems to idle proper and not stall until I ride it, I think because it's loose shakes around and doesn't feel like it makes a good seal like the hole is tapered wider on the top or something. When I hit a bump going slower I would stall out at lower RPM's

[Alleyoop]

Great, that is what I thought it is pushed in to far and ALREADY blocking fuel when cold.
Is that the ORIGINAL ENRICHER or is that a new one? Mine is not as long as yours and I have a 24mm carb and it fits good and tight. Are you sure that the "C" Hold down clamp is not bent and in the GROVE all the way around. If you can take a picture of it installed.
Alleyoop

[indiana]

It doesn't seem bent or mal-formed in any way. It's a picture I found on the web of one that is exactly like the original one I have in there now I ordered a new one that looks different (shorter) but is supposed to be a match for this carb, I will see how it fits when I get it. I will post as soon as I get the new one installed.... Thanks!..