Just got finished putting my 250cc together, the shifter got bent. Went to start it up, ran for about 5 minutes then would start stalling at idle, could get it going with the choke closed and constant throttle but it will die out completely and I'd have to wait a few minutes to get it going again.

So I took the carb apart cleaned all the jets and needles, made sure the holes were open, cleared out the gas put in new gas with some sea foam to help break down anything that might be lingering. Clean air filter.

Made sure the bowl stays full of gas, everything is connected. Still same problem, once it warms up it will stall out and sometimes if you close the choke you can get it to run a little longer then it dies and won't start back up for a few minutes.

Any ideas?

P.S I can start the thing with no choke at all, but it's not really cold here, lowers 70's. Don't know if that would matter or not.

 

So it runs fine cold with or with out the choke?

When you cleaned the carb... did you remove all the jets and the fuel screw?

Are you still using the stock (Chinese) spark plug?

 

Yes I can start it cold without using the cluthc, ambient temps around 70 degrees f.

I changed the plug when I first got the ATV, but I intended to check it today to see what it looks like, I will update you on that.
And I cleaned everything I could find to clean on this carb. Not sure which jet and screw is which aside from the main jet and air/fuel screw, but here's a link to a bunch of pictures. I assume the the one on the very bottom by the overflow outlet is a fuel screw too? or is that just a drain plug? either way I clean it too, thing looks brand new.

I'm at work now blowing it out with air, so when I get home I'll put it back together, check for leaks and see if a super cleaning did the trick

for carb pics
ATV pictures by danthalis - Photobucket

 

In the 4th row of pics it shows the bottom of the carb...both jets removed and the fuel screw still in the carb...If you dont take that screw out and blow carb cleaner and or air thru it your not cleaning the pilot circuit...(basically your not cleaning the inside passages of the carb)

The screw on the side of the carb is the idle screw...

 

@mywifesquad, the amount of rows of pictures will change depending on how big your monitor is, fyi. For me there were only 3 rows. :P

 

Well I certainly look brilliant dont I?

Pictures 10 and 11...

Thanks Rainier2

 

Well the 2nd good cleaning and blow-out seems to have solved (or greatly reduced) the stalling out problem. I can get it to start and run when warm.
I see I took the picture with the a/f screw still in it, I did take it out though and gave it a good cleaning too.

Now after it's warmed up once you get past 1/2 throttle it bogs out and dies. Going to take the thing apart once more when it cools and make sure something hasn't come loose (or whatever the original problem was has just moved on to the next jet lol)

Also was in the process of attempting to adjust the air/fuel screw when this started to occur so that might be related too. On this bike it's extremely hard to adjust the air/fuel screw when warm because the exhaust pipe is literally right there and I keep burning the hell out of myself trying to get to it, might try fitting it with something that will make it more accessible provided I can think of something.


PS I did spray some flammable stuff around the carb/intake seal to check for leaks, no reving ot stalling so that seems to be in order

 

When you pulled the main jet out did you unscrew the main jet holder? There are holes in the side of it that could have a effect.

I either slip a piece of vacuum line over the fuel screw and turn it that way or with a pair of needle nose pliers.. Id start at 2 turns out..(on a 2 stroke its a air screw... on a 4 stroke its a fuel screw)

If the needle(hanging from the carb slide) has a clip on it Id put it in the bottom groove....closest to the pointed tip.

 

Well I had some mild success today. The main jet had come unscrewed D'oh

Got it back together, got it going and it kept going. Rev'd it up a bit let it idle, messed around with the fuel screw I let it run for a good 20 minutes, so the 2nd cleaning helped. Went for a ride around the block ran good up the gears. When I pulled the clutch it stalled out, but got it going right away. Did that twice, the second time around had to wait a second. By the time I got back to the garage I had to close the choke to get it going then limped it in and shut it off. About a minute later it turned on just fine.

So it's improving quiet a bit, but still has an issue. Kind of sounds like it's running out of gas in the bowl though? Gas pours out the hose when I pull it off the carb, but maybe I will replace that fuel line just to be safe and continue to f' around with the fuel screw. It still stalls when I pop the gas from a low idle.