carb float height issue

molash

New Member
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May 29, 2023
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United kingdom - Edgware
Hello,

When i first got the kit, there where no leaks but engine was way too rich, so i moved c-clip to 2nd leanest as that was pretty good, once the jet kit arrived i put a 65 jet in since the 70 would bog at full throttle.

This is when the issues began after about 3 tanks of gas.

I noticed the carb would leak if i let the engine idle for more than a few seconds, I set the float height to 21mm (no idea what it was stock) and that didn't really work as sometimes it leaked and other times it didnt, so i bent the float prong thingys up even more and that seemed to fix it but i noticed after a couple of seconds of WOT, the bike would cut out indicating not enough fuel as well as this occasionally the carb would leak which sounds contradictory to what i just said, but yes it would leak and the bike would not cut out at high speeds and would start much easier (only took one kick in 5C weather when usually i have to ride it to start), and then the next day it would go back to not having enough fuel in bowl.

This leaves me to today, where it doesn't leak but still doesnt have enough fuel in bowl, I have a feeling its to do with the float not sitting flat on the metal prongs, i will send a pic tomorrow.

i have tested for air leaks and replaced the fuel filter since the stock one was leaking
thanks

ps carb is a bofeng model
 
A lean condition can also cause bog at WOT which may not be related to the float.

You DO want the engine to 4-stroke at WOT near redline.

If you changed jets on a baby engine, and now things are starting to settle together, you may now have the wrong jet.

Also, if you have that tiny filter in the tank remove it and keep the inline attached. Those screens can clog very easily and slow flow.

I recently fixed my float issue because it was only at 15mm.
 
You made the float height so high (low) that the bowl is not full enough to maintain WOT without leaning out. Your carb leak is likely the float needle and/or seat not sealing and thus constantly trying to feed a small amount of fuel into the bowl. Or the float itself is hanging up inside the bowl, often caused with the carb being at too much of an angle or a manufacturing defect hanging it up somewhere.
 
You made the float height so high (low) that the bow is not full enough to maintain WOT without leaning out. Your carb leak is likely the float needle and/or seat not sealing and thus constantly trying to feed a small amount of fuel into the bowl. Or the float itself is hanging up inside the bowl, often caused with the carb being at too much of an angle or a manufacturing defect hanging it up somewhere.
Now that you wrote that, the float could have a crack in it.
 
Now that you wrote that, the float could have a crack in it.
I had a float in an NT carb that had a little plastic protrusion at the seam that was just enough to snag the inside of the bowl and cause a tiny issue. It's always the dumbest stuff with these ultra cheap parts lol
 
i set the float height again last night only to find out this morning that the needle was jammed in place, had to remove it and clean out carb, i put in a 70 jet and i will find out how it fairs tonight. Anyway i was planning on adjusting the clutch until i remembered i stripped the threads on the flower nut screw which prevents the nut from spinning, any idea how to remove it?
 
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