So I recently bought my new YZ250F and I was wondering if it was normal for fuel to be leaking out of carb overflow after riding and with the fuel turned off, for example: After riding turning the bike off and the fuel off, loading onto trailer and driving home with fuel leaking out of overflow onto the trailer.

Also I found it strange that when I turn off the fuel and lean the bike over fuel rushes out the overflow. I do understand that when the fuel is leaned over that the carb float cannot function properly filling the bowl and overflowing but I don't see why it would be happening if I had my fuel turned off in the first place.

You need to check your float height and see if it is to low, the problem seems to be that the float is not pressing the needle valve up to the top of the seat and that will allow it to spill out, it should not do this on a new bike really and if your bike is new then take it back to he retailer and get them to fix it! In fact tell them you want it fixed DON'T ask. Usually only happens to old bikes when they have been used for a good few years or miles.

If you can lean the bike over running and it dosen't overflow then it's fine,if not then the float is out of adjustment.

Fuel leaking when trailering is not uncommon,best to shut the fuel off and let the bike run till the carb is empty,this makes starting the bike easier.When your going down the road over bumps and train tracks fuel will splash up into the intake and soak the filter,my wr (basicaly the same bike) can be a royal pain to start if I dont empty the carb before trailering.

As for taking it back to the dealer don't bother as you have no warenty and this is something you will need to do fairly often anyway so might as well learn how.The carb is easy to get off and back on,when instaling the bowl screws dont crank them down just tighten them up, changeing them for allen bolts is a good idea as the star head strip easy if over tightened.

The dealer might do it once for free but I doubt it as MX bikes see lots of abuse and if you have had even one crash then they will most likely laugh at you.

I thot a bike this age would be fuel injection,,,

Well bugger me " its the only bike in its class with a carb , Kiehin39mm ,, 37 bhp. down 5 horse on the KTM,

Edited September 18, 201410 yr by blackhat250

BH yam has kept the cost down by not going FI and the handeling of the yz is way better than the King Till Monday.Keep Taking Money

POS .HP is only part of what makes a MX bike fast what the yz lacks in HP is more than made up for in the ridability. The KTM is very twitchy in the whops and the YZ soaks them up,the Yz tracks better out of corners and the power deliverly is spot on.Makeing it the easier /faster bike to ride. Honestly I can say if ther was 1 bike I would never own it would be a KTM.

Sorry to Hi jack your carb question Jake but I hate KTM's over priced IMO and the only bike that I have seen snap in half on more than 1 occasion just comming down from a big jump.

Haha, thanks dt502001 and slice I appreciate the responses. Thanks for the advice and after reading that I assume it's because I haven't been draining the carb after riding. Just to be sure I will try leaning the bike over while running and checking the overflow. Thanks heaps!

So I can now confirm that it overflows when running if lent over. I might adjust that carb float.