carb leaking gas

hi I just started my cr80 for the first time on my new top end and the carb leaks gas when I shut of the engine what could cause this? also is there a way to keep my exhaust pipe from leaking where it meets the exhaust manifold?

As for your carb, your float height could be off, however it is un common to just happen.

I would put money on the fact that your float needle is not sealing properly due to a bad seal or most likely there is trash, dirt, or jelled gass stuck in the carb. I recommend cleaning out your carburetor.

my carb is spotless I will probably check the float level.also my exhaust pipe is leaking oil where it meets the manifold is there a good way to seal that? it's spitting oil all over my motor maybe I can stop that by playing with the air screw?.my jetting is stock and I am running 32.1

I am sure you need to adjust your jetting. Probably wouldn't hurt to re pack your silencer, get new o rings for the pipe.

Just bought an 04 250 and it leaked gas. I adjusted the float and did the trick. Almost exact same situation on my buddies KTM 250.

Need any tips on adjusting the float or do you have it covered?

my pipe doesn't line up perfectly so I don't think an o ring would help much,but for now I have a piece of rubber and a clamp going around the manifold it still leaks some though. tomorrow I'll try to make a better rubber seal and finish the heat cycles and than for a test ride:ride:.oh and I did lube everything pretty good before putting together my top end so maybe it will stop leaking black oil after a wile cause I only started it two times for about 7 minutes each? is it okay to ride it the way it is?. for the carb the gas only leaks when the engine isn't running so all I have to do is turn off the petcock when the engine is off because I don't feel like taking it apart again right after I got it running.anyways thanks for your help I'm looking forward to the test ride tomorrow.

Just bought an 04 250 and it leaked gas. I adjusted the float and did the trick. Almost exact same situation on my buddies KTM 250.

Need any tips on adjusting the float or do you have it covered?

yes that would be helpful info when I get around to taking it apart again,I have the specs on what the float level should be set at now all I need is to know how to set it, so if you could help me out that would be great thanks.

Your float hight is probally off. It's not uncommon for them to get out of wack whiledong a top end. Seems like when they sit sideways off the bike and everything they get a little out of spec. Happened on mine and was a 10 min fix.

yes that would be helpful info when I get around to taking it apart again,I have the specs on what the float level should be set at now all I need is to know how to set it, so if you could help me out that would be great thanks.

So here is a thread that does a decent job, but if you don't know what you are looking at, it can be quite confusing.

http://www.thumpertalk.com/forum/showthread.php?t=412662

Basically, if you are leaking gas when the bike is off, then your float is letting too much fuel in and its going out the overflow tube. So your floats aren't pushing the fuel inlet valve up (off) soon enough. If you are holding all the pieces as if it were attached to the bike, you want to bend the tab holding the fuel inlet valve UP. The picture in that thread is showing that whole assembly upside down. So when your floats go up, it will push the fuel inlet valve up sooner. It doesn't take much!! Just a hair should do the trick. Put it all back together, turn the fuel petcock back on, move the bike around, and check for fuel leaks.

Someone will correct me if I'm wrong on all that, but thats from my experience. I didn't have the spec on what the floats should be at, but I know they were letting too much in, so thats why a hair should do the trick.

So here is a thread that does a decent job, but if you don't know what you are looking at, it can be quite confusing.

http://www.thumpertalk.com/forum/showthread.php?t=412662

Basically, if you are leaking gas when the bike is off, then your float is letting too much fuel in and its going out the overflow tube. So your floats aren't pushing the fuel inlet valve up (off) soon enough. If you are holding all the pieces as if it were attached to the bike, you want to bend the tab holding the fuel inlet valve UP. The picture in that thread is showing that whole assembly upside down. So when your floats go up, it will push the fuel inlet valve up sooner. It doesn't take much!! Just a hair should do the trick. Put it all back together, turn the fuel petcock back on, move the bike around, and check for fuel leaks.

Someone will correct me if I'm wrong on all that, but thats from my experience. I didn't have the spec on what the floats should be at, but I know they were letting too much in, so thats why a hair should do the trick.

Well said! It shouldn't take a lot. I think my YZ250 is between 5 and 7mm or something like that. I don't have a metric ruler so I converted mesurements onto a standard ruler.

okay I decided to go a head and set the float I didn't measure anything I just bent it just a hair and that fixed it.it's still leaking black oil out the exhaust I made a better seal but it still leaks just a little also it smokes quite a bit evan when it's warmed up what is the best way to fix that without changing the jetting? air screw? just looking for ideas every thing in the carb is stock.I bought the bike with a blown top I finely rebuilt it and I have one more heat cycle to go than it's time for a test ride :thumbsup:

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