Date: 21-09-21  Time: 18:27 pm

Author Topic: Petrol pouring out of carb overflow ?  (Read 382 times)

dilboy

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Petrol pouring out of carb overflow ?
« on: 02 May 2021, 04:01:42 pm »
New pump fitted
New fuel relay fitted
Bike turns over,but petrol is leaking out of the right hand,first carb,over flow,


Any ideas amigos ?


Cheers
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Disorderlypunk

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Re: Petrol pouring out of carb overflow ?
« Reply #1 on: 02 May 2021, 04:36:07 pm »
New pump fitted
New fuel relay fitted
Bike turns over,but petrol is leaking out of the right hand,first carb,over flow,


Any ideas amigos ?


Cheers
🤘🧙‍♂️🍺🤘


carb float valve stuck
stand upright and give a few god taps with a screwdriver handle or something, was a common problem on methanol speedway bikes back in the day
if it still keeps happening then carbs out time or at least the float bowl if you can get in there

dilboy

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Re: Petrol pouring out of carb overflow ?
« Reply #2 on: 02 May 2021, 04:44:16 pm »
New pump fitted
New fuel relay fitted
Bike turns over,but petrol is leaking out of the right hand,first carb,over flow,


Any ideas amigos ?


Cheers
🤘🧙‍♂️🍺🤘


carb float valve stuck
stand upright and give a few god taps with a screwdriver handle or something, was a common problem on methanol speedway bikes back in the day
if it still keeps happening then carbs out time or at least the float bowl if you can get in there


Cheers
Took the float bowl off,cleaned it,replaced it,still overflowing ?


Blockage maybe ?
"Lay down your soul to the gods rock 'n' roll"

Gnasher

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Re: Petrol pouring out of carb overflow ?
« Reply #3 on: 02 May 2021, 05:28:46 pm »
The metering valve is more than likely shot. 
Later

Disorderlypunk

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Re: Petrol pouring out of carb overflow ?
« Reply #4 on: 02 May 2021, 05:44:26 pm »
yep sounds like either the float level tab has been bent off level or the float valve and body needs replaced

sgpwwg

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Re: Petrol pouring out of carb overflow ?
« Reply #5 on: 09 July 2021, 12:34:20 pm »
I had the same problem, it was the rubbers in the carb on that had gone hard, I bought a £20 rebuild kit and replaced rubbers, the float valve and bit it slots in to and this sorted it. Double check you oil as I had the fuel fill up the engine as the rubbers on the carb we so  perished.

unfazed

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Re: Petrol pouring out of carb overflow ?
« Reply #6 on: 09 July 2021, 03:26:35 pm »
Most likely the Float valve O-Rings, however there is no need to buy a kit as removing the O-ring is usually easy enough and the quality of the original need valve and seat is usually much better than non Mikuni replacements.

You need to get 7.5mm ID X 1.5mm CS (cross section) x 10.5 OD FKM/FPM 70 or 80  O rings Asking for Viton is the same but the FKMFPM is more specific. I have changed many of these over the years and only once have I had to replace the Valve seats and that was on a 1974 Honda 4
With the carbs off and the float bowl removed, Remove the Float and needle then remove the Float valve retaining screw. Spray around the edge of the float valve with wd40 and allow it soak for a while.Tape the jaws (duct tape is best) of a pliers . Lightly grip the valve and twist the valve half a turn. if it twists then pull it out gently. If not apply more WD40 and  leave it soak for an hour.Prise off the O-ring taking care not to damage the o-ring seat. Do not mix up the seats as you will reduce any float height issues later. I use a small pick or a very small jewellers screwdriver. Spray the seat and new O-ring with WD40 and prise the O ring on with your fingers.
Spray the Carburettor Valve seat with WD40 and push the Valve back in. Screw in the locking Screw.
Continue with the other 3 and reassemble the carbs.

If you undo the Main Jet you may as well replace the O Ring there also and that is a 5.5mm ID x 1.5mm cross section x 8.5mm OD also FKM/FPM 70 or 80