I have what I assume to be a Chinese atv. I believe it is a 70CC.

I first purchased it and the guy said someone tried charging it with a car battery charger, and would not start after that, so he decided to start messing with the wiring harness, cuz melting was going on. Anyway. I bought it off of him, I resolved that issue, I figured out the wiring, well, I just hooked up what is necessary to run. After repolacing everything electrical, meaning the CDI, the coil, and the Stator, I am now getting spark. So I was happy, OK, now I should have a decent running little quad for my son. Ok, try to start it, well, I was wrong, since it was sitting so long, I assume the carb is all gummed up. Took it all apart and cleaned it, and ok, we should be good, well, nope, still nothing, well once in a while, it will try to start or if I let it sit for a little while, it will start for about a second or so, then die. Checked, still getting spark, but plug is still dry.
Ok, what the heck, for $30 I may as well change the carb, who knows, maybe there is something in there I just cant get clean.

Well the carb came a couple days ago. I installed it, still, same problem. No gas is getting to the motor. I am definitely getting gas to the carb, float is full, but nothing getting from the car to the plug, well some must be a little bit, cuz once in a while it will speed up a little like it wants to start.

If I use starting fluid or put gas right in the cylinder by the plug, it will run until the gas is gone. SO I do not believe it is valves or pistons or timing, cuz like I said, it runs fine if I manually get gas to the plug.

For some reason it is just not getting fuel from the carb, to the plug. You would thing it would if I choke it, but still, the plug stays dry. Anyone have any idea why this would be.

Thanks for any help

 

Are you using a fuel filter ?
Reason I'm asking is some are not marked for fuel flow and can easily be installed backwards.

 

Yes I am using a filter, but I do know I am getting fuel to the carb, cuz if I open the float bowl drain, fuel will come out.

 

In this case, your issue sounds to be carb related for sure. First, is the intake clean from the airbox to the carb, and carb to motor? If it has sat then sometimes critters build nests in there and cut off all the air flow. I don't suspect this is the case though. Another quick is that the carb slide should not be fully closed, otherwise no air/fuel can be drawn through to the cylinder.

 

Thanks for the reply. I checked air box, it is free of debris, although I did find it looks a little dry rotted and has a couple slits in it. I assume this could cause running issues, but I wouldn't think it would cause it not to start, would it?
What I tried also is I took the intake tube (I assume it is called, the metal curved piece between the carb and the motor) off, disconnected it from the motor, and sprayed starting fluid right into engine, it ran until the starting fluid evaporated

I also checked the valve clearance, seems to be fine, and checked to make sure the timing didnt jump, that is all still lined up. Just to make sure.

I am stumped, the only thing it can be is not enough fuel to spark plug, but cant figure out why not.

What is a good starting point for the two adjustment screws on the side of the carb.
Or any other suggestions?

 

What position is the carb slide in? It should be almost, but not quite fully closed. I know you said you cleaned the carb, did you make sure both the pilot and main jets were unobstructed? The pilot on that machine is going to be tiny. That is often the first place they clog up and it won't start if that is the case.

 

for the fuel mixture start at 1/2 -2 turns out.. For the air mixture/idle screw i would adjust until you see the slide just opening.. Have you tried pegging the throttle and squirting some gas directly into the carb? Then let go of the throttle and start? I had to do this on one of mine then once i got it started i had to keep spraying it for a bit to keep it running.. Think i had a air lock or something aftr i got it running under its own power it was fine

 

Scooter,
I replaced the carb, so I know it is not dirty now.

Zrock,
Ok, Ill try that and Ill check the slide to make sure. Yes I have tried gas directly with throttle wide open. Like I said before, I can get it t fire up for a few seconds, but always dies right out.
As far as the air box, is that very important, as I said before, there was a rip in it, would that some how prevent the suction of the fuel into the engine if there is no airbox.

Thanks for the suggestions, keep them coming, it still is not starting.
I don't understand why this is being so difficult. Uggggh

 

If it is the air filter that is ripped, it should still start as long as the jetting wasn't way lean to begin with. If the air box itself is broken and you are still running the lid, that may cause it to be to lean and start hard. I would think that you would still get some fuel on the plug though. Will it start if you spray starting fluid in the intake instead of directly into the cylinder via the spark plug hole?

 

At the moment I have the airbox disconnected from the carb, as it is ripped right where you clamp it to the carb. But I believe even if I keep the choke closed, it will try to start briefly, but then not. I would think if I kept the choke on, it should flood it out, but still, the plug does not get wet.

If I remove the carb and the intake tube and spray starting fluid right in the intake hole, it will try to start, and run for a brief second, but of course this is a huge vacuum leak. LOL

Tomorrow Im gonna mess with it again. Ill make sure the mixture screws are set like you said and see what happens tomorrow, but I do not have confidence.