Fuel Leak

[clark4131]

My carb is leaking fuel out of the fuel bowl drain. I can't tighten it enough to stop it as I dont want to strip out the threads or damage the seat...I think that's why it may be leaking as it is. Any ideas as to how to get it to stop? It's just a minor drip right now, but I'm not happy about it ? . BTW, what the p/n for a new fuel bowl?...SC

[Indy_WR450]

Your float is stuck! Tap the side of the carb to stop it. if it persists then reset the float level to 9mm as per Yamaha manual. If that fails then there is an o-ring on the check valve that can get dirt traped in it. This is were the float opens the fuel flow. ?

[sharpmarble]

If it is the bowl drain, did you put a new o-ring in it? www.sudco.com

[clark4131]

I'm gonna pull the whole thing apart on Saturday and give it a good cleaning. I'll check the float level then and adjust as necessary. Thanks for the help...SC

[justarider]

You may need a new float needle if you can't get it to stop leaking. On some needles, there's a rubber tip that gets a grove worn into it. On metal needles, same thing applies. Usually changing the needle and seat and checking the float level cures the leaking carb.

What is happening is the needle doesn't stop the fuel flow from the tank. (gravity feed). The fuel fills up in the bowl and runs out the overflow tube, then out the overflow line.

Sometimes you can see trails of what looks like oil or liquid on the trails when you ride. This is the overflow from somebody's carb. Even if it stops leaking, if you don't have a good needle and seat, your carb will still overflow when you are riding due to vibration. The bike may run fine but your gas mileage and range will really suck.

For the price of a needle and seat, and the price of gas these days, you might save yourself some money by putting in a new needle and seat.

[Indy_WR450]

If it is the bowl drain, did you put a new o-ring in it? www.sudco.com

I doubt it is the o-ring on a new bike but if it is:

Then it is the part #37 on the FCR MX drawing on the Sudco web site. ?

[clark4131]

I don't think it's the overflow as the four tubes coming off the top of the carb have been routed to my airbox. The thing that is leaking is the bowl drain screw, #46 on the Sudco diagram. I'm just curious as to how the float level being screwed up can cause this to leak. I'm thinking the seat may be bad and that my only remedy would be to JB Weld the thing shut as the entire bowl is not available for purchase separately...SC

[clark4131]

Any other ideas?...SC

[Rip Wheeler]

If the float is stuck, a small wrap on the carb will set it free sometimes. Also, another common scenario is a small piece of debris in between the needle and seat. With it overflowing, the float can keep pressure on the debris and hold it in place. To clear this, you need to turn the fuel off, run it dry (or use the bowl drain), this will allow the float to drop, releasing the debris and then turn the fuel back on to wash it out of the seat and into the bowl. ?

[bg10459]

Steve,

I suppose you cleaned the hole and the screw real good. Can you see inside? If there is nothing there, maybe try putting some teflon tape on the screw, make sure it goes over the tip, not just the threads. Worst case, pick it out with a dental pick. I think this would be better than JB welding it.

[new2blu]

My carb is leaking fuel out of the fuel bowl drain. I can't tighten it enough to stop it as I dont want to strip out the threads or damage the seat...I think that's why it may be leaking as it is. Any ideas as to how to get it to stop? It's just a minor drip right now, but I'm not happy about it ? . BTW, what the p/n for a new fuel bowl?...SC

Check out this company http://www.carbparts.com/keihin/keihin_parts_list.htm Look under the street FCR carbs--nothing listed under off-road for fuel bowls. You may need to call them because there is many different part numbers for the fuel bowls.

[Dan_Lorenze]

I'm not sure I should admit this but since Toyota let the cat out of the bag.... I've tapped on the carb with a tool or hammer to free the float valve from time to time.. Infact just this week my CT70 (125cc upgrade) had the same problem with it's 24mm carburetor, leaked like crazy.. I took a small hammer to it an tapped it, in about 5 seconds the leaked stopped and I was good to go.. Sometimes the float valve gets stuck... ?

[clark4131]

You boys is some smart fellers...Stuck float is now unstuck and all is well as I am leak free. I gave her a good cleaning inside and out, but now I have a different problem. Since it's in the 90's now, I dropped my pilot down to a 45 from a 48 and I have a HUGE off idle bog now. I had a slight one with the 48, but it was not a big issue. This has got me thinking...Perhaps my bog is due to a lean pilot circuit rather than the AP squirt, leak jet, etc. So now it's back to the drawing board to get it figured out. Wish me luck...SC