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Super Sport revving to 5k on start up


CB750 Member
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United States
The previous owner said that the number 3 carb was leaking fuel out of the float bowl. Ran and idled fine. Took the carbs off, noticed only one of the float bowl drain screws had an O-Ring on it, replaced all four, no more leak. Put the carbs back on and it fired right up without the airbox on. Now that the airbox is back in, it fires up, chugs around 700-1500 rpm for a few seconds then shoots up and holds steady at 5000. Any ideas? I've been trying to adjust the idle speed screw but that makes no change. Sets thattugyryuyyhiffd
figured it out. My mix screws were turned way out.
Now, after a warm up ride, I pull the clutch in and the bike revs to 3k and seems to idle there. If I hold the front brake tight and let the clutch out just until the bike starts to want to move and hold it there for a few, it'll idle between 700-1400. Any ideas??
Have you checked for vacuum leaks in the boots? Is the throttle cable adjusted too tight holding the throttle open? Have you checked the ignition advance to make sure it moves free? Have you done a carb sync? Checked ignition timing?