TTR 125 Carb Overflow Leaking Gas

There is obviously a problem with this style of carb... Google this or do a search here and you get a ton of hits. The problem is nobody responds with the fix and most of them are one and done posters.

This carb is only a year old. Dealer put in a new carb when I bought it because it set for awhile.. I realize it could be the needle seat or the floats. Based upon the number of problems on this issue, is it possible

that when you put the bowl back on that something is causing the floats to stick?

Tomorrow I'm going to take the bowl off and try to blow through the gas line and see if I can get it to seal or hook up a gasoline and try that and see if that needle will seal up.

Has anybody else have any solutions?

If you have not had the carb apart, I would think it is just dirt causing the needle to not seat properly. You can lightly tap the bowl with a screw driver and try running it again and see if it stops. If you have taken the carb apart and removed the float needle, make sure you have replaced it correctly. If I remember correctly, the thin metal wire like spring piece that is around the tab that pushes on the needle, can be installed in two ways. (180 degrees around if that makes sense.) If you have the carb apart you may understand a little better. Post a picture and I will point to the area. I found in one direction I would get fuel out of the overflow and not in the other direction. Maybe just a coincidence or might be a fix for you.

Good Luck

You can take that carb off in 45 seconds. I timed it. So, in the time it took to post, you could be well on your way to solving the problem. :thumbsup:

It has to be a sealing problem with the needle and seat. I suspect that the solution will be obvious when you take the bowl off.

Always blow in the fuel intake and move the float up and down to check for sealing before you put the bowl back on. It just takes a second.

Ya, i have taken it off multiple times. It is easy.... I didn't find anything obvious. I tried to blow through the fuel tube and it would seal when the float was raised. So it seems with that test it wouldn't be the problem. I put it back together and took it around the block a bit and no leak. I want and did other stuff for most of the day. I then took it out again, this time I went to a field and hit a few hills and small jumps. Return the bike to my driveway, waited and it again started to leak. I then tapped the carb pretty good and it stopped. As I mentioned in my first post... I believe something is causing the float to stick. I don't know... I'll have to test some more... Here is a pic of the needle, as you can see this carb is brand new.ImageUploadedByThumper Talk1395545965.207888.jpg

You mite want to check if the Float level is correct.

Wait it doesn't look adjustable on that carb.

If you are sure everything is clean and there is no damage to the needle or seat, try rotating the needle 180 degrees so that the metal wire is facing the other way and replace it on the tab.( In your photo the little wire  part at the end of the needle is near the 12 o'clock  position bordered by the square white plastic of the float frame) I know it sounds strange, but since I flipped this little spring tab around I have not had this issue. Maybe I was just lucky. I think that the metal wire hangs up on something during the float movement causing it to stick and leak. Give it a shot if nothing else works.

Good luck.


I was able to do some testing and believe I solved the problem. The float has a peace of metal that you can bend. I tried this before when I tested the float by blowing through the fuel line, but it still leaked.. I was real close in buying a new needle seat.

I figured I would give it one more shot. This time I was going to do my testing with the fuel line on. When I was blowing it would seal but the floats were sealing too late. I didn't realize this until I tested with gas. So I adjusted the metal up where it would close earlier. Also made sure when floats were down gas was flowing. I put it back together and so far so good. The float height might still be a little off, I haven't done the official testing with the clear tube describes in the manual. This bike is for my eleven year old, so as long as gas is flowing we are good.

I guess it shows you blowing air isn't a bad test but using actual fuel is a lot better. Thanks for the ideas guys.

Hey guys,


I recently took my Yamaha ttr 125 old carb off to replace it with a brand new carb. Being a rookie, I forgot to take pictures of how the different tubes hook up to the carb. I have done a little trial and error, but am not sure if I have found the correct hookup. When connecting it like I think I am supposed to, my overflow valve will pour constant gas out when the gas is turned on. My questions are...


1. Can you please help me correctly hook up the different tubes including the fuel line?

2. If the carb still overflows when correctly hooked up, how should I address this issue on a brand new carb? 



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