November 14, 200520 yr Hey people.....Im new to this forum...as you know. I currently own a Techno 95 250cc......and i have a petrol leak... the fuel is coming directly out the over flow pipe seconds after i turn the fuel on!!! Its not really bothering me, but it makes my sessions limited because i run out of petrol faster I have introduced an air line to it to clean it...striped the carb you name it i have done it....i went to my shop nearest me which dosent work on trials bike but they said i need to get a new pin and gasket.. it this my only way out?? all help is appericated!!!
November 14, 200520 yr I bet the needle valve is stuck open (see attached diagram.) If muck gets in the recess where the valve sits it can't return to the closed position, the carb fills with fuel and it exits through the bowl overflow.
November 14, 200520 yr Author Even still though i tried that!!! what else is there to do??? Or get new pin and gasket??
November 15, 200520 yr Do you mean the pin that retains the valve actuator? Maybe, but if it's already moving freely, I'm not sure that would help. Ditto bowl gasket. If the valve's OK and you've stripped and cleaned everything then I'll back out and let someone more knowlegable than me step in... sorry I can't be of more help.
November 15, 200520 yr Actually, one other thing does spring to mind - if you've definitely removed and cleaned the actuator and valve, maybe it could be the floats themselves. Do they move up and down freely in the bowl? Is one heavier than the other? If one (or both) of the floats are damaged in any way they can allow fuel to get inside which obviously affects their weight and relative bouyancy. I can't wait until EFI is standard on all trials bikes. It's really annoying Edited November 15, 200520 yr by neonsurge
December 1, 200520 yr The last thing I always do before re-installing a carb is to turn it upside-down and suck gently on the fuel line (get your mind out of the gutter!), and make sure the needle is sealing. Also...make sure the floats don't have fuel in them. You can also put them in a tin of fuel to be sure they float nice and high.
December 1, 200520 yr fuel flow into the float bowl is unrestricted and will flow and flood the carb until the float/s rise and lift the needle valve so that it closes the fuel supply off. check if the float/s are leaking by removing from carb and holding close to ear and shaking, you may hear fuel in them if it is leaking and/or immersing in a glass of petrol and look for air bubbles. check and double check they are set at the right height. if the carb is more than a couple of years old replace the needle valve and its seat they wear and / have high spots you cant see. considering the cost and hassle and for piece of mind replace float/s and needle valve and seat. job done guaranteed!
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