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marc1345

Beta 250 Rev 3 Leaking Fuel Out Of Carb

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Hi guys im new to the forum and to trials biking. Iv just rebuilt the top end and got it all running i left it on a very slight tilt and came back the next day to fuel on the floor, its coming out of the carb but everything looks fine is there anything i can do to sort this ??

thanks marc

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It means the needle is not sealing perfectly to the seat, the fuel exceeds the max fuel height in the carb and it comes out the overflow

To a certain extent it is fairly common but it depends how bad it is, in a perfect world you should be able to never turn off your fuel and the carb would never leak but.....

You may need to replace the needle, another trick is to use a little bit of lapping compound on a Q tip and gently lap the seat

The other thing I hear is that you should not use the one way valves that dirt bike guys use, they let pressure build in the tank and this can push fuel the only way out which is past the needle

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It means the needle is not sealing perfectly to the seat, the fuel exceeds the max fuel height in the carb and it comes out the overflow

To a certain extent it is fairly common but it depends how bad it is, in a perfect world you should be able to never turn off your fuel and the carb would never leak but.....

You may need to replace the needle, another trick is to use a little bit of lapping compound on a Q tip and gently lap the seat

The other thing I hear is that you should not use the one way valves that dirt bike guys use, they let pressure build in the tank and this can push fuel the only way out which is past the needle

common problem on rev3 you might be able to fix by resetting float height or new needle valve , other wise lampkins drill them to prevent this

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This might help, I had the same problem and this worked a treat.

http://www.r2wtrials.co.uk/html_files/betacarbsetup.html

http://www.trialscentral.com/forums/topic/310-beta-mikuni-billy-traynor/

Also check the fully open position isnt going too far and the pivot pin is straight and smooth.

Good luck.

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Mine leaks if I leave the tap turned on after riding.

So far I've leaked all over my nephews van on the way home from a trial and in three different places in my bike shed.

Trouble is I either forget to turn the tap off or can never remember which way is off (now use 'back - off') as my reminder.

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The setup tips should solve any problems during a trial but you really should switch the tap off during transit, it is what it is there for after all, as the movement on a trailer or in a van can cause the floats to move slightly and let fuel through. Never mind that we used to automatically switch off at every section in the old days, we switched off every time we parked the road bike!

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That's the trouble with FI as there is no tap on my KTM 950 so I get out of the habit, although there is one on my trail bike but I don't seem to forget that so much.

Not had any problem during a trial but if it's on it's stand then there is no reason why it wouldn't leak then.

By the way, are the prop stands designed by people who live on rocks or with plenty of trees to lean against - no use in a nice muddy Sussex field as it just keeps on sinking.

Sorry, getting OT.

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Do the carb set up mods as it works. It's worth turning the fuel off in the van or garage though for safety sake if nothing else.

Nobody likes a fire ball in the house or van!

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