Fuel leak?

JackGarrett94 · Derestricted Danger Joined: 16 May 2014 Karma :

My bikes leaking fuel but first i will give you a story of what happened because everyone likes a story.

I took my bike green laning on saturday for the first time, I rode up to thetford with some friends it was about 40miles to thetford. The day started of great, Bumping up and down sliding about, it was a bloody good laugh, I hit a log and dropped my bike, she was fine now heres where things went wrong, We where riding down a lane and this sand pop out of know where my friend in front of me wobbled and nearly crashed (i was laughing my arse of seeing him slide about) so i slowed down but it wasn't enough i crashed.. I picked my bike up and she was leaking fuel from the over flow, I assumed the float was stuck, We spent a few hours trying to fix her but couldn't, Ended up getting van to pick me up and take me home, Took 7 hours for a van to show up i didn't get back till half 2 in the morning. Fun times.

Right now what is causing my bike to leak fuel from the over flow? The float seemed fine it wasn't stuck, I couldn't see if anything was broken or not i was really confused, Im going to take her apart tomorrow and have a better look, I assuming the float isn't closing of something when it floats. My bikes a honda xr125.

Any ideas? getting the bus to work today sucked!

mudcow007 · World Chat Champion Joined: 01 Feb 2012 Karma :

does it have a vacuum operated fuel tap?

the diaphragm could be toast in the tap.....

Islander · World Chat Champion Joined: 05 Aug 2012 Karma :

Float valve not seating properly would be my guess.

JackGarrett94 · Derestricted Danger Joined: 16 May 2014 Karma :

map · Mr Calendar Joined: 14 Jun 2004 Karma :

Vacuum operated fuel line is where carb(s) create a vacuum and pull fuel from tank into carb(s). The carb(s) had diaphrams (that split) to achieve this). Fuel tap usually has on, reserve and prime positions. As you need to bypass (prime) to fill carb(s) to get bike started in the first place.

Float in the carb sticking means fuel not forced properly out of carb so just keeps filling and overflowing. Sometimes a sharp tap with a screwdriver handle works to free. Otherwise disassemble and clean.

Could just be dropping the bike has dislodged crud that's affecting the carb.
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Islander · World Chat Champion Joined: 05 Aug 2012 Karma :

map · Mr Calendar Joined: 14 Jun 2004 Karma :

YBR Ric · Spanner Monkey Joined: 16 Jan 2012 Karma :

Time to dig up Ye Olde Ethanol in the petrol attacking certain fuel system parts myth; except having seen what happens to some types of O rings I now know it's no longer a myth Crying or Very sad

The impact force may have been the last straw for the float valve.

Ethanol attacks hydrocarbon rubbers - eg nitrile rubber fuel hose along with gaskets and seals made with or from hydrocarbon rubbers.

It's possible the float valve tip has become swollen or distorted and is failing to seat correctly causing a leak.
OR it could just be worn. If Ethanol damaged then a like for like replacement will eventually suffer the same fate. A Viton tipped float valve is needed to prevent this.