Carb Issues.... AGAIN!!

So I made a post a week or so back saying my carb was pouring gas out of the overflow hoses after being ran or sometimes just the gas turned on. Here is what we did this past week..
 
• Ordered a new float needle (OEM yamaha)
• Installed new float needle
• Cleaned carb out with carb cleaner
• Hose coming from bottom of bowl was CAKED full of mud about 4-5”. Cleared that out.
 
After that: Problem stopped at 1st, ran it around the yard a few times getting on it, etc., stopped to check on it and it started POURING out again.
 
So now we are thinking the float possibly has a hole in it (according to local yamaha dealer mechanic) and that if it does the float wont close and gas will continue to pour through.
 
• Ordered new floats (OEM yamaha)
 
Its like a “hit or miss” issue. It does it every little bit. We took a handle of a screwdriver and tapped the carb and it stops for a little. I brought the idea up that since it is cold where i live and temps are crazy right now, the rubber on the float needle gets hard and doesn’t set completely until warmed up? I researched all i could and heard some people have this issue in winter while in summer they never have a problem.
 
If anyone who has had this same issue, please give me suggestions or a fix to this.

The float could be sticking and not returning if it stops after you tap the carb. I would make sure it’s not binding and it moves up and down freely and not getting caught on anything.

I'm sure you are frustrated, but keep in mind that the carb is really a simple device that you can fix yourself---it's not some mysterious tangle of wires connected to plastic boxes with circuit boards, etc.  

You can easily test your floats by submerging them and looking for bubbles, but it is unlikely that they are leaking.  I have seen bad floats before, but I don't think I have ever seen them on a Japanese carburetor in 40+ years of motorcycle wrenching. I suspect that you may have some dirt or debris in the tank, fuel line, or pet cock that is getting hung up in the float needle area and preventing it from seating properly.  

Since you have already replaced the needle and seat, you can see how it works--the floats rise, and it closes off the fuel entry.  It's just a matter of figuring out why that is not happening.  Is there contamination in the seat?  Did you assemble it correctly?  Did the float needle tab get bent so it is set wrong? Is the little wire clip on the needle around the tab?  If necessary, you can check the needle operation by hand.  Just take the float bowl off, reconnect the fuel line, and work the floats with gentle pressure from your finger to see if it shuts off the fuel flow.  Obviously make sure you are not smoking or have other open flames around when you do this!

rpt50 has given great advice here. The first thing that came to my mind was maybe the little wire loop wasn't over the tang on the floats. 

If what rpt50 suggested does not work polish the seat with brass-o and a q tip

rpt50 has given great advice here. The first thing that came to my mind was maybe the little wire loop wasn't over the tang on the floats. 


This is exactly what happened to me the other day 2017 250x and my carb is leaking.... I had changed some jetting a week before. Opened it back up and the needle seat wire loop was not on the float tang right. Fixed that and no more leak.


This is exactly what happened to me the other day 2017 250x and my carb is leaking.... I had changed some jetting a week before. Opened it back up and the needle seat wire loop was not on the float tang right. Fixed that and no more leak.
ok well im not going to dig into right now but ill pile these suggestions ive gotten so far and do each one and check them. Ill try to get pictures this time.
21 hours ago, RidingWithStyle said:

So I made a post a week or so back saying my carb was pouring gas out of the overflow hoses after being ran or sometimes just the gas turned on. Here is what we did this past week..
 
• Ordered a new float needle (OEM yamaha)
• Installed new float needle
• Cleaned carb out with carb cleaner
• Hose coming from bottom of bowl was CAKED full of mud about 4-5”. Cleared that out.
 
After that: Problem stopped at 1st, ran it around the yard a few times getting on it, etc., stopped to check on it and it started POURING out again.
 
So now we are thinking the float possibly has a hole in it (according to local yamaha dealer mechanic) and that if it does the float wont close and gas will continue to pour through.
 
• Ordered new floats (OEM yamaha)
 
Its like a “hit or miss” issue. It does it every little bit. We took a handle of a screwdriver and tapped the carb and it stops for a little. I brought the idea up that since it is cold where i live and temps are crazy right now, the rubber on the float needle gets hard and doesn’t set completely until warmed up? I researched all i could and heard some people have this issue in winter while in summer they never have a problem.
 
If anyone who has had this same issue, please give me suggestions or a fix to this.

The hose coming from the bottom of the carb is the only overflow hose, the other hoses coming from the side of the carb are vent hoses. I seriously doubt fuel could find its way up into any of the vent hoses unless the bike was layed over on its side. So did you actually see fuel pouring out one of the vent hoses or has it always been just the overflow hose? Some good advice above, but I didn't read anything about float adjustment. I assume you have but have to ask, did you check the float height? 

I accidentally droped my float bowl one time when working on the carb, the short fall from my hand to work bench was enough to bend the brass overflow pipe down towards the bottom of the bowl, it would have effected the level at which fuel entered it had I not bent it back. I would inspect your overflow pipe closely just to see if it could be either bent or cracked or maybe even loose where its pressed into the bowl, also with the bowl off, test it by filling it to the top and see if any gas leaks out the bottom or the hose.




The hose coming from the bottom of the carb is the only overflow hose, the other hoses coming from the side of the carb are vent hoses. I seriously doubt fuel could find its way up into any of the vent hoses unless the bike was layed over on its side. So did you actually see fuel pouring out one of the vent hoses or has it always been just the overflow hose? Some good advice above, but I didn't read anything about float adjustment. I assume you have but have to ask, did you check the float height? 



I accidentally droped my float bowl one time when working on the carb, the short fall from my hand to work bench was enough to bend the brass overflow pipe down towards the bottom of the bowl, it would have effected the level at which fuel entered it had I not bent it back. I would inspect your overflow pipe closely just to see if it could be either bent or cracked or maybe even loose where its pressed into the bowl, also with the bowl off, test it by filling it to the top and see if any gas leaks out the bottom or the hose.

We have checked float height. Like i said the guy at the dealership said sometimes the float can get a hole in it over time and cause it to leak even with the floats closed. We already ordered new ones so we will have to see if that fixes it. Until then im out of town so i cant work on anything.

Did you replave the entire needle valve or just the needle? I have had the o-ring where the valve seats in the carb body go bad on really low hour bikes.

7 hours ago, mikedabike said:

Did you replave the entire needle valve or just the needle? I have had the o-ring where the valve seats in the carb body go bad on really low hour bikes.

That's an interesting observation.  I just replaced the needle and seat for a buddy, and the O-ring that came with the Yamaha part (OEM package) really looked to small for the job.  It was noticeably thinner than the one that came out, but it did seat correctly and seems to be working in his bike.  

Also make sure it not coming from tank. Take tank off and petcock off clean and start over. Only takes little piece to hold needle open little. Then you know its not that anyway. Also make sure float not bent one higher than other, seen that too

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