Motorcycle fule line diagram for a 299cc 2003 defiant

Most likely is it carburetion or engine timming.

The bike is a knock off ....
Here is the actual service manual for the bike

http://nans.1gb.ru/motomanual/Yamaha/Yamaha%20XV250.pdf

No diagram bit if you get the correct o-rings and replace them that should solve the problem and if not you will need to disassemble the fule tank, pump etc to install a new quick connect assembly.

hmm..I don't think the first answer is correct I have an 86 suburban 350 and the filter is on the front of the carb under the air cleaner just as the fule line goes into the carb. there is about a 3/4 inch nut to open the fule line and the filter is inside.

its a fule problem check the carbs or injectors? your getting big sploshes of fule going into the engine this makes it try to rev up in a big way!!!

this sounds like fule starvashion blocked running jet's in carb or fule lines blocked,,,strip both and clean them out

The one line is the supply line, the other is the return line, the other one would most likely be for evap emissions.

start by cleaning all the fule lines and pipes out look at the fule tap in the tank it may have a blocked filter on it,then blow trough all the lines right back into the fule tank if fule is reaching the card strip the carb and clean out all the jets plus the flote bowl your bike is not getting any fule

i would start by having a compreshion test done on the engine if it has good compreshion start looking for a fule problem clean out the carbs and fule lines and change any filters in the fule tank a new set of spark plugs never hurts as well test for a good spark by jaming a spark plug down on the engine caseing and crank the engine over if its a good bright spark thats working ok also check the ignishion switch and kill switch clean them both up with switch cleaner just squirt them well and work the cleaner well into the switches it wont hurt them and it will do them good to be have a bit of lub in them as it keeps the wether out of them

its not loosing the fule its running back into the tank, you have an air leak in the suckshion side of the fule line, a pin hole some were or a leaking joint it could even be in the fule pump itself or the fule filter "o" ring is leaking air but thats were the problem is try fitting a none return velve to the fule pipe upto the pump

it's defiantly your head gasket replace that and you will be in good shape