scotty97 Posted April 27, 2009 Report Share Posted April 27, 2009 My bruvs 2003 beta rev 3 has the tendacy to p*ss petrol out of the carb. after reading a lot of threads of the bike leaking out of the atmospheric pipes of the carb we had a check and the carb is actually leaking through the overflow pipe. Is this common aswell???? Whats the best fix? we tried the fix where you bend the metal that the floats press against to shut the petrol off. The next fix to try was to drill the two holes and block the end with loctite. Can you please comment on which way you got around this common problem of the REV3 Quote Link to comment Share on other sites More sharing options...
chewy Posted April 27, 2009 Report Share Posted April 27, 2009 I will be watching this for the solution also. I think basic problem is that the carb is angled down to the engine so have lived with it .I am told that changing float height could result in engine stalling/stopping going downhill. I think some folks connect the oveflow to the breather.. watching also for the definitve cure Quote Link to comment Share on other sites More sharing options...
slapshot 3 Posted April 27, 2009 Report Share Posted April 27, 2009 My bruvs 2003 beta rev 3 has the tendacy to p*ss petrol out of the carb. after reading a lot of threads of the bike leaking out of the atmospheric pipes of the carb we had a check and the carb is actually leaking through the overflow pipe. Is this common aswell???? Whats the best fix? we tried the fix where you bend the metal that the floats press against to shut the petrol off. The next fix to try was to drill the two holes and block the end with loctite. Can you please comment on which way you got around this common problem of the REV3 See the "Sticky" thread at the top of the Beta pages. Take the time to do the mods, float heights etc etc mikuni's are not the best but a well set up one should give you no trouble. only time I've had probs at the overflow is if there's been muck in the carb Quote Link to comment Share on other sites More sharing options...
mtwallet Posted April 29, 2009 Report Share Posted April 29, 2009 mine pi***d fuel out when i bought it 2 years ago so i took it back to the dealer where i got it and all he did was set the float heights, fit a float bowl extension and put about 6 inches of pipe from the overflow thats at the bottom of carb on float bowl and turn it upwards and cable tied it to the fuel inlet pipe so it was a few inches higher than the overflow and ive never had a drop of fuel come out in the 2 years ive had it and bike runs really sweet, will start pointing up or down hill no problem and doesnt stall going down steep hills either, i dont know how to post pics on here otherwise i could take a pic for you Quote Link to comment Share on other sites More sharing options...
dan williams Posted April 29, 2009 Report Share Posted April 29, 2009 OK two different systems here. The two tubes that come out the side of the carb are atmospheric vents. They are never meant to see fuel, only to keep the air pressure above the fuel in the float bowl at ambient. In some cases fuel will get splashed up into these vents and because the tubes attached to them are too long and end below the float bowl they act as siphons and will drain the tank if left unchecked. There are a few solutions to this. Raise the end of the tubes so they are higher then the float bowl or drill a couple of extra vent holes into the bowl or cut a hole in the vent tubes above the float bowl. The single brass tube that comes out of the bottom of the float bowl is the overflow. If the fuel level in the float bowl gets too high this is where the excess leaks out. This indicates either a damaged float (sinks to bottom of bowl so never shuts off fuel supply), a damaged float valve (check valve and seat, both can be replaced on Mikuni), the float level is set too high or a float is binding on something usually the float bowl gasket. Since you say it's coming out the overflow on the bottom of the float bowl I'd pull the carb and check the valve seat for dirt and make sure the seat is clean and smooth and the rubber tip of the valve isn't damaged. Next check to see if there is any fuel that has leaked into the floats. There should be nothing in the floats but air and no damage should be visible on the floats. Re-assemble the floats and move them through their travel and look to see if they could be binding on anything. If they are do what you must to get them moving freely with out interference. It's possible that they may not show a problem with the float bowl off so look to see any potential rubbing spots and take an X-acto to them if its the gasket or file a little bit if aluminum. A quick check (though it spills fuel) is to reconnect the fuel line with the float assembly together and turn on the tap while holding the floats closed. if no fuel leaks out the valve is working. Quote Link to comment Share on other sites More sharing options...
nzralphy Posted April 30, 2009 Report Share Posted April 30, 2009 I had this on my 270 Rev3..... Empty your tank and check the gas is/was clean. Flush if necessary. Fit a new fuel filter. Check the float valve for muck or damage. Chech the floats dont have fuel in 'em. Go find Billy T's words on how to adjust the two float tangs. Take some time to get this right. Do it slowly!!! Then link the two side vent tubes together over the top of the carb with one tube. Put a small breather hole in this tube - on the under side, of the top of the u bend. It never leaked fuel again. Happy. Quote Link to comment Share on other sites More sharing options...
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