More carb issues

Ihcc126

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Hey guys newbie on this forum but mechanic of 15 yrs pulling my hair out on this 80' xs400 special II. So I dunked the carbs 3 times and even used my agitation device with it for extra cleaning. Bike runs awesome bottom end top and everything except I get a high idle after warm up......but......... if I slightly push down on the left carb it idles down to normal. Before we state the obvious yes the carb boots to engine are brand new with new gaskets and yes I even bumped down the float level incase that may have been my issue. I have sprayed them down with wd 40, brake cleaner, and even water while running g and no change. Please any input is appreciated thanks
 
But what would it have to do with pushing the left carb slightly down and it being perfect idle then?
 
You synch with manometer? If you don't have one you can make one easy cheap (Google/YouTube). Before that, you should have checked valves to ensure in spec.

After those 2 steps, only other thing would be an air out vacuum leak somewhere that is being negated when pushing down. Just because carb boots are new doesn't mean seal is perfect...

Possibility of float needle not sealing?
 
Check timing and valves. When the carbs are torn down, they should be bench synced first. Its not a must-do, but it can get your carbs close enough to be able to ride it normally.

Stating the obvious, have you adjusted the idle at all? If you are running lean, you can get a high idle too.
 
I haven't messed with the valves since this is a one owner bike with less than 4k original miles. I cant see at 4k miles they are out yet but I'll tryem anyhow. And the carbs are bench synced and the bike runs phenomenal even bottom end is great very snappy off idle. This issue I had with the old boots witch were dry cracked so I of course thought this was the issue but not even the slightest difference with the new ones
 
Yeah but you would think when I spray them with wd40 or brakleen it would change the rpm but I have hosed them down when running and no change ever in rpm
 
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