Carb rebuild problem

[specialmatty]

Hi, I just rebuilt the carbs on my 1982 xs400. It took a couple of tries to get the float level set correctly, I have three different manuals that say three different things, finally used a clear hose to set it. It started up and idled great at first, I took it around the block to get it warmed up and then synced the carbs. I then took it for a longer ride, it ran well but would stay around 3000 rpm. I was able to use the bike to slow the engine down and once I got it to less than 3000 rpm it would idle down normally. Ran it like this for about 45 minutes, then parked it for a couple of hours. Started it up again to ride home, fired right up but was idling really low, I turned the adjustment screw to bring up the rpm’s a bit, started riding, and the rpm’s just kept going higher and higher, it’s now revving around 5000 rpm’s and I can’t get it to come down. Any thoughts? Do I need to pull apart the carbs again?

 

[CaptChrome]

Sounds like you have an air leak which is creating a lean mixture and high rpm. Check for an air leak from the carb butterfly shafts through to the head.

 

[tstidham]

And if you still have the vacuum petcock,try disconnecting the vacuum to it and plug the hose or cap the port. Set the petcock to PRI for prime, it bypasses the vacuum shut off.