joboo Posted June 6, 2012 Share #1 Posted June 6, 2012 I consider myself very good with these carbs but I have a problem that has me a little stumped. I was out of town for a week, came home, started the bike as usual, a little choke and she fired right up and sang like a bull gator. After she warmed up, choke off, sitting idling while on the side-stand, the idle started decreasing and fuel barely trickled out of the overflow and the engine died. The fuel stopped. Restarted and once at idle, same thing happened, smooth perfect throttle response, no other symptoms. Stood the bike upright, started it again and same thing happened at idle. With any throttle at all it is fine. I think you can rule out floats and needles as the fuel stopped when the engine died. I suspect it may be a pinhole in the #1 carb diaphragm but I am guessing that would not normally kill the engine. With extra fuel, I didn't have any rough engine run like I would have expected. This one has me guessing! I think I will order a new set of DS-1s as I have never replaced all of the diaphragms at the same time, only as needed and I am thinking that they stiffen with age and one could be stronger than another. All inputs are welcome! Link to comment Share on other sites More sharing options...
Marcarl Posted June 6, 2012 Share #2 Posted June 6, 2012 I guess the first thing that has me stumped is your comment about fuel coming out of the overflow,,, can you explain that a bit? Link to comment Share on other sites More sharing options...
Yammer Dan Posted June 7, 2012 Share #3 Posted June 7, 2012 Sea-Foam!! Link to comment Share on other sites More sharing options...
joboo Posted June 7, 2012 Author Share #4 Posted June 7, 2012 lol @ YD I always use seafoam! Marcarl the two tubes that vent the carbs at the top. They are connected with a "T" and a hose that terminates on a metal fitting behind each of the front cylinders. Maybe they are called something else, but that is where the fuel will pump out in the event of a stuck needle or float. Link to comment Share on other sites More sharing options...
Marcarl Posted June 7, 2012 Share #5 Posted June 7, 2012 Well if there is fuel coming out of those tubes,, that's a good place to start to fix. Run some Seafoam, and see if that helps,,, a whole can in half a tank or less might do it for you. The float valves are sticking or you have some dirt in the needle of the valve,,,, worst case scenario would be a bad float, but do the cleanup job first and then see. Link to comment Share on other sites More sharing options...
joboo Posted June 7, 2012 Author Share #6 Posted June 7, 2012 Thats why this problem is so confusing, if it was one of those things the flow would not stop when the engine dies, the fuel pump would tick and it would continue to pump out fuel. That is not happening, not one tick and the fuel stops. I always run seafoam in every tank, the symptoms don't add up to a float, needle or seat. It seems to be vacuum related which is why I was suspecting some sort of diaphragm issue and it only happening at idle. Thanks for your reply, as always hoping that I don't have to tear em off again! Link to comment Share on other sites More sharing options...
Squeeze Posted June 7, 2012 Share #7 Posted June 7, 2012 There's a Safety Device in the Bike, called Fuel Pump Relay. It controls the Operationof the Fuel Pump, based on Spark Signal Input. If the Motor stops, the Spark Signal stops, so does does the Fuel Pump after 5 Seconds or so. What you see at the Vent Tubes is normal, like it should be. My first Impression is, there's a Float or the Floater Valve stuck. Drain the Carb Bowls while the Key is off, then turn the Key on and hit the Carbs carefully with the Grip of a Screwdriver or a Piece of Wood. Shut the Key off and On again until the Fuel Pump stops on it own, not by time. Link to comment Share on other sites More sharing options...
RSTDdog Posted June 7, 2012 Share #8 Posted June 7, 2012 If there is fuel coming out of the overflow tube, there is too much fuel in the carburetor bowl, float (or floats) is not sealing. The seat for the needle valve has an oring around it. Even if there is no trash on the needle, if the oring for the seat (brass part) is bad, fuel can leak around the seat even when the float needle is seated. Keep in mind that Seafoam has alchohol in it. So does pump gas. I'm not sure if you literally run seafoam all the time or periodically. I am not a fan of continuously running solvents with alchohol through my carburetors. Bad enough its in the fuel. Alchohol and solvents will deteriorate the rubber parts with time. I personally prefer Marine Stabil or Startron since neither has alchohol and both contain additives to combat corrosion and fuel phase separation associated with ethanol. If draining and flushing the float bowls as suggested above doesn't fix it, I would go back in and have a close look at everything.Fuel leak is nothing to take lightly. RSTDdog Link to comment Share on other sites More sharing options...
joboo Posted June 7, 2012 Author Share #9 Posted June 7, 2012 Thanks for the input guys! will give it a shot and let you know what happens. Link to comment Share on other sites More sharing options...
MiCarl Posted June 7, 2012 Share #10 Posted June 7, 2012 I agree, carburetor overfilled. Not a diaphragm. You can also close the fuel cock and run the motorcycle until it dies. Turn fuel back on and try it again. Draining the bowls down then turning the fuel on causes a rush of fuel past the needles that can flush debris away. Link to comment Share on other sites More sharing options...
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