cv carb overflow problem
 

Ok one day my cv carb on my 90 evo started to overflow out of the overflow hose on the float bowl. I got a new float needle and float. And resealed the carb while I was there. I set the float level to spec from the HD manual. Still overflowing. Also I blew out all ports, vents and all that. The bowl drains with the screw, so I know it's venting properly. Kind of at a loss here. And when I put the gas to the carb with the float bowl removed and push up on the float by hand, it seals off the gas. Just wondering if anyone has seen anything like this before and what they may have done to fix it. Thanks a bunch.

The seat where the float needle sits may be worn out or you are setting the float level wrong.

well i guess the seat is the only thing left. Well i followed procedure in the manual and the float level is right according to that. Is that hard to replace? the seat I mean

That pretty much means it is either set wrong or the float is bad...remove the float and see if it has gas in it.

The seat is metal and the needle is rubber so unless you dinged the seat up I doubt that is it. The float could be set wrong, the float could be bad, your gas line may be falling apart thanks to the ethanol, your tank could have rust etc in it or your vent could be plugged causing pressure to build up when the tank is shaken. Try replacing the fuel line and put a filter in it after you double check the flost level. Then check your tank vent, it could be in your cap or may be a seperate vent hose depending on the model of your bike. If the drain screw isn't seating properly you will have fuel draining from the hose too.
Hope this helps.

Float bowl valve for sure. Easy to replace. Get a rebuild kit and give it a good cleaning with carb cleaner while you have it off of the bike. New gaskets, o-rings, etc.

EDIT: The float is hung up somehow. Take it apart and clean it. With the bowl cover off, carb upright, and the float and needle in place, make sure it actuates properly. Check the rod that holds the float bracket in place. The float should move up and down very easily.

I have and clear fuel filter coming from the tank. All new gas line because I just rebuilt the top end of the engine and had the tanks off. I've had the carb off, resealed it and cleaned it thoroughly. Every port. And put a new valve and float in it. I guess i need to know if that seat is replaceable, it sure doesn't look like it, may press in. I'm going to try to clean the surface of that. Maybe me pushing it is more than the float floating can do? And by the way, my I tried it with the gas caps completely removed to eliminate any venting issues there.

so the seat lookes good and with the new valve there's no reason it wouldn't seal. I did find that the damn inlet elbow is cracked. Why the f is that plastic? But I bet when that bowl fills up some air gets in that crack and overflows the bowl because it's a bit closer to the carb vent then the tank vent. Because when it overflows it's just a dribble then stops, dribble then stops, etc. It's not constant. I need to replace that piece of shit inlet elbow. How do you get that stupid thing out? I'll search around the site, I'm sure I saw others having issues with that.

The elbow is fused to a brass fitting which is pressed into the aluminum carb body. I bored the brass out and tapped the hole with a 1/8" pipe tap, then put a brass elbow. NOTE, it is very easy to split the aluminum housing when tapping the hole. Be gentle.
Docwatson

Like doc said there is a replacement part for this press in. A write up on it was in Hot Bike magazine not too long ago. Looked for it but like a needle in a haystack. Sure the instructions come with the part. Must be rather common. Replacement part is solid brass. Post what you find out. Getting ready to fix a older 97 that has set for 8 years with the same problem. Assumed it was the needle and seat. I have seen stopped up sink drains that were cleaner then this bikes' tank