bralkan Posted October 28, 2007 Share Posted October 28, 2007 Sometimes it will idle and then slowly die. Othertimes, it won't idle at all and I have to keep the throttle open, just a bit. I have to leave the choke open as well (idle jet prob?!). The Idle adjustment screw on the bottom of the carbs doesn't seem to help much in maintaining any kind of idle, let alone one at 1200rpm. Any suggestions? Thanks, -John PS - I am a noobie, but quick and willing to learn. Link to comment Share on other sites More sharing options...
Moderator drewpy Posted October 28, 2007 Moderator Share Posted October 28, 2007 Sometimes it will idle and then slowly die. Othertimes, it won't idle at all and I have to keep the throttle open, just a bit. I have to leave the choke open as well (idle jet prob?!). The Idle adjustment screw on the bottom of the carbs doesn't seem to help much in maintaining any kind of idle, let alone one at 1200rpm. Any suggestions? Thanks, -John PS - I am a noobie, but quick and willing to learn. take the Idle adjustment screw out and if it is blunt (ie not pin sharp) the bottom part has snapped off in the carb preventing any mix on idle. ( very common as I've seen loads) if it is sharp, you have a bockage in the pilot system and the carb needs stripping also try balancing the carbs and setting timing and valves correctly as that will be the next easiest Link to comment Share on other sites More sharing options...
bralkan Posted October 28, 2007 Author Share Posted October 28, 2007 take the Idle adjustment screw out and if it is blunt (ie not pin sharp) the bottom part has snapped off in the carb preventing any mix on idle. ( very common as I've seen loads) if it is sharp, you have a bockage in the pilot system and the carb needs stripping also try balancing the carbs and setting timing and valves correctly as that will be the next easiest When you are talking about the idle adjustment screw, are you talking about the screw on the bottom of the right hand-side of the carb? I backed it off and it looks rounded, not pin sharp. But I don't see how it could have broken anything off in the carb - it just seems to move a lever up and down.. Now, I don't know what I am really looking at. I have a Haynes but it hasn't been much help. Also, the carbs were cleaned about 2 months ago. Had the two jets and floats replaced. It had to basically sit for 2 months after that because of ignition system problems (waiting for parts stinks). Thanks again. Link to comment Share on other sites More sharing options...
Cy Welch Posted October 28, 2007 Share Posted October 28, 2007 When you are talking about the idle adjustment screw, are you talking about the screw on the bottom of the right hand-side of the carb? I backed it off and it looks rounded, not pin sharp. But I don't see how it could have broken anything off in the carb - it just seems to move a lever up and down.. Now, I don't know what I am really looking at. I have a Haynes but it hasn't been much help. Also, the carbs were cleaned about 2 months ago. Had the two jets and floats replaced. It had to basically sit for 2 months after that because of ignition system problems (waiting for parts stinks). Unless you have other than 1980 carbs, the idle mix screws are on top of the carbs under brass plugs as they were designed to not be adjustable. Not idling could of course be many things, but start by making sure there are no vacuum leaks. Unless they have been replaced, check the vacuum piston diaphrams, as they wear out and leak. You can get them on ebay or you can get the piston and diaphragm from mikesxs.com (the later xs650's use the same bs34 carb as the 1980 xs400). Also check the carb holders as they tend to crack and leak also. Link to comment Share on other sites More sharing options...
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