Carby Problems - Mikuni TM40 - XR650R

Hey guys i have had my Mikuni TM40 on my BRP for quite a while now and it has been great, that is until today when i went about my normal ride and it started off great with me starting the bike and gearing up whilst waiting for it to warm up as usual until it randomly stalls and then i notice fuel pissing out?

I start it up again and manage to get going somehow and then every time i came to a stop it wanted to stall and did several times. It seemed to have gotten better once it was warmer but on the trail several times it would be pissing fuel out at one time and not another when sitting or riding whether it was straight or leaning.

It still seemed to run ok but what could have caused this because the float level shouldn't just change by itself and it wouldn't be stuck would it?

Any ideas before i rip it off?



check the bowl, float valve and seat for debris

Just read your post, mine is doing a lot of the same. It continually pisses gas. When it first started doing it I got a lot of weird serging action while it pissed everywhere. I took the bottom of the carb off and and seemed fine, float seem right on. Didn't know about float valve. Did you clean that, if so did it help?

Mine is a 2000 XR650R, just bought it and was told it has been jetted and uncorked.


Pulled the float valve today and cleaned it, took care of pissing gas problem! Now I just gotta fine tune it.


Took mine apart today and had a look at everything and it all seemed ok, so put it back together and tried it, seemed ok, will have to test later during the week.

Hopefully its alright.


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