carburetor overhaul - now dies with throttle

I just finished overhauling and cleaning my carburetors which where overflowing and flooding any time it ran (the bike had sat for over three years). I have cleaned out the tops and bottoms (carb cleaner, compressed air), cleaned/inspected all jets, replaced all float seats and needle valves, and reset the dry heights of the floats to 16mm. I had to reset the float heights because my needle valve pins sat 1mm higher than the original ones.

Now, no more overflow, but the bike starts and runs only with full choke and dies when given throttle. I attached some clear tubing to one of the drains and took a fuel level reading. The level is about 1/4 inch below the float chamber gasket. I have read that the level should be no more than 3mm below the chamber gasket. So it seems my fuel level is too low.

I am going to re-adjust the floats to raise the fuel level, but I want to make sure that is what would be causing the bike to die when given throttle. Can anyone confirm this?

Also, I am a noob. What/where are the pilot mixture screws and could they have anything to do with my problem?

Thanks

 

Check with Rick-Co-Matic's old school carb cleaning thread.

Two things
First I would reset those float levels and I am understanding that the float levels should be checked withthe bike running. Should be even with the float bowl screw. These carbs are float level sensitive since they are a draw through design Too High Fat Mixture Too Low Lean mixture.

Second
When you have the float bowls off take a pen light and see if the small jet in the bottom of the well is clear. Also check the brass tube that goes into that well and make sure the bleed hole in the top is clear. I had to take my carbs on and off a few times to get them right. Good Luck and let us know what you find.

 

Also, I am a noob. What/where are the pilot mixture screws and could they have anything to do with my problem?

they have a big influence on how your bike runs. they are top front of your carbs, next to the pilot jets, not shown in manual, as your not supposed to fiddle with them, set by manufacturer for emmissions, this is rubbish as you need to get at these screws, on some models they are in the possition I said but hidden under caps/covers.

 

Did you clean the emulsion tubes ?

 

Are the emulsion tubes contained inside the main jets? If so, No, I did not remove and clean them. In fact, I hadn't heard of them until you just mentioned it, so i did a little research.

Could dirty emulsion tubes be part of my problem?

 

Any Dirt Will Give you a bad time. The carbs mist be surgicaly clean

 

don't take this wrong, but you did drain and clean out your tank and got rid of that 3 yr old gas, right?

 

Yep, draining out the old fuel was one of the first things I did.

Yesterday I re-adjusted the float heights to 15mm (1mm lower than the service manual recommended level) to let more fuel into the bowls. Then, put carbs back in bike. That brought the fuel level up to just below the float bowl gasket. At first it was still dying with throttle, but was starting to respond a bit. At that point I still had the air intake tubes off so me and my father in-law put the palms of our hands over a few of the air intakes on the carbs to feel for vacuum. I gave it a start with the intakes covered up and it fired right up strong and responded to throttle. Once it warmed up it idled smoothly with no choke! Apparently restricting the air of those intakes and creating strong suction for a moment did something, because that triggered it to start running.

I finished putting it back together and took it for a first ride! It is running awesome! Once it warms up it shifts great over all gears, throttle is responsive at all ranges. I'm psyched.

It still doesn't start/idle well cold though. It takes a good while to warm up before it responds to throttle without dying. But once its hot, its great, I adjusted the idle knob to get it just above 1000 and it stays right there.

I did notice that the carb pilot screw covers had been removed. So, someone at some point must have tweaked em. Could the adjustment of the pilot screws affect the cold starting/idling of the bike?

Thanks to everyone who responded to my questions and posts.

 

sounds likre dirty pilot jet and/or enrichment tube.

Enrichment tube (and hole in carb bowl) are tiny and will clog easily.
Be sure these are clear for smooth starting.