Yamaha Passola SA50 1981 carb leak

[iamjuliagreen]

I have recently acquired a 1981 Yamaha Passola kickstart scooter and as soon as petrol was poured in it poured straight back out again through the float bowl overflow and up through the air vent.

Assuming the floats weren't floating properly, I adjusted them, to no avail.

Finally, I replaced the entire carb with a spare, only for exactly the same to be happening as soon as petrol was added...What to do?!

Just to let you know what I have tried so far...upon advice from the original Haynes manual...I have checked/changed the pin and float for damage, cleaned the pins and carb, replaced air filter, removed and cleaned the exhaust.

Also, when trying to kickstart, it now kicks dirty petrol out of the exhaust.

Please help, I'm coming to the end of my tether with it, but really don't want to give up on the old girl!

[motobrox]

The carb floods when the floats dont close the needle valve (the bit like a tiny brass pencil under the float adjuster tab). Then needs to 100% clean, moving and sealing to shut the fuel off as the floats rise. The fuel in the exhaust is part of the flood problem.

[oldenuut]

Hi,

I've had the same problem. Renewed the floatvalve and adjusted the floatlevel according to the Haynes manual.

You best do this with the carb dismounted from the engine: use a small bottle as fueltank and check / adjust the floatheigth (it took me a couple of hours to obtain the right floatlevel).

Also check if the hoses to and from the bimetal-valve on the cilinderhead, the carb and fuelcock are in good nick and connected to the right ports. Vacuum is the name of the game of the fuelsystem, especially when the engine is cold.

Also check if the fuelcock membrane is in good condition. I finally renewed the fuelcock (80 Euro!!), engine is running sweetly now and no fuelleakages anymore.

oldenuut