Good evening-
I am having issues with my BMX 110 quad carb. The quad sat for a long time because the PO couldn't figure out that the kill switch went bad in the ignition switch. Anyway, once I got that problem fixed and went to run it, the carb idles way too fast and then revs wide open. I took the carb apart and cleaned it, put it back together and it still does it. Now there was fuel coming out of the overlflow. I took the carb off again, took it all apart and cleaned every piece. The jets are clean and all ports are free of restrictions. The throttle cable was on its last leg, so I replaced it as well. I just went out and tried it with a new throttle cable, the idle adjustment screw backed out 2 turns, the air/fuel mix screw backed out 2 turns and it still is doing the same thing!!! I can't figure this out. What have I forgotten. When you close the choke it will idle down, but when you open it up, away it revs. Help please!! I am giving this to the neighbor for his little girl, and I don't want give them a quad that won't run right. Sorry for the long winded post.

 

First check to see if you have free play in the throttle cable.. if the throttle cable is tight it could be raising the idle.. most have a adjustment in them..

The fuel screw is set by a "turns out from seated" method.. Id start at 3.. The idle screw is not like that..it is adjusted so the engine idles..

If its got the stock spark plug.. Id get a NGK C7HSA and gap it to .028

 

Thanks for the reply. I have slack in my throttle cable. I tried it when it was hooked up to the thumb control, also left it unconnected and manual pulled it. I don't seem to get much response at all in reference to higher revs, which is really wierd. Not really sure what that means?? I have replaced with the NGK plug, I will check the gap again this evening.

 

Usually when you have problems revving its got to do with the holes in the side of the main jet holder being plugged.. So it idles and responds from idle ok?

The thing is all of these are jetted way to lean to run correctly from the factory. The higher you are above sea level the better..

 

It only idles nice when the choke is all the way on. Once you start to open the choke it opens wide up. It does not seem that the idle screw is having much effect on it which is weird. I live pretty much at sea level, just north of Seattle. I have a Kazuma 110 falcon that runs just fine. I tinkered with it a bit when I got it and now, no problems. I switched out the carb with a spare one I had. The other had the choke cable which runs up to the ignition switch. I put one on with the manual choke that is adjusted at the carb. Both carbs are having the same issue. Should I tear the carb down again? I ran air and a small little pin through all of the holes pieces the other day, maybe I missed something??

 

Is the carb slide in all the way? 1 way it only drops about 1/2 way down.. the other way(180 degrees) it drops all the way in the carb...

 

It sounds like your carb is dirty.. pilot jet if it wont idle/run with out the choke.. Main jet for high rpms..

Id take the carb completely apart (if you leave any jet or the fuel screw in it wont get clean) and make sure you can see light thru the pilot jet, main jet and the holes in the side of the main jet holder. then make sure you can spray carb cleaner or air thru the hole the pilot jet and fuel screw came out of..

Once you can verify all the holes are clean we can move on..

 

The carb slide is all the way in. I made sure to put it back correctly. I will tear it down completely again and check, re-check all the parts to make sure they are clean. Thanks for your time and guidane with this.

 

Okay- finally had a chance to get it taken apart and cleaned. Got it put back together and it ran without reving, got it warmed up and did the adjustments to the air/fuel screw and got the idle adjusted. Took it for a spin and noticed fuel pumping out of the overflow. I think the float is set too high. I am not sure how to set this. I made sure the needle and seat are moving and sealing correctly. I hooked a spare hose to the inlet and when I turned the carb over, I was not able to get air through the hose. Tilted it back down and air flowed. This tells me it is working. Where should the float be set so fuel does not flow out of the over flow? This carb sits a little tilted back towards the motor. Thanks so much for your help.

 

Glad to hear you got it running well.. most floats are set so they are level with the carb when turned upside down.. What you need to do is lower the float level a little so it doesnt over flow the bowl. You do that by bending the little tab. gently. It might take a few times..