Idle was fine for a week after stage 2 dynojet and pipe. 1350 rpm. Today, when I rev my bike, idle stays at 4000 rpm for like 30 seconds before it goes back to 1350. Throttle cable not sticking. drain tubes patent. What's wrong. Help me out . Thanks. Can't find it on search.
Even when riding, out takes a while for rpm to go down.

 

Are you watching the actual carb linkage to insure that it's closing when you release the throttle? Is that little intake manifold stub either plugged off or has the proper hose attached to it? When you put your carb back in are you sure the intake manifold clamp is tight? Has your idle mixture screw backed out or fallen out?

Tough to diagnose without seeing or hearing the bike. Sounds a little like a vacuum leak or something interfering with the throttle linkage, cable, or grip.

 

odd...but, it idles smooth?...not bouncing around...4,000 rpm idle is usually the exact rpm when i have my choke out...i'm just brainstorming, but maybe something came loose inside...completely guessing...good luck on the fix...let us know what the problem is when you find out....

 

Everything is in place nothing missing. Linkage goes back with a snap. Its just the rpm status high longer before it returns to normal.
Bike also hard to start. Have to use choke. Maybe clogged jets? I'm at a loss.

 

my was having difficulty starting and keeping idle..valve adjustment and new shims fixed that problem....

my idle was crazy...i mean bouncing around like bunny..4,000 to 1,000...back and forth....eventually cut out....did another valve check..everything perfect...just to see what happens...i replaced the spark plug and it fixed the problem..i must have damaged the plug when i took out the spark plug or when i was putting it back in...

 

Might try the spark plug. Bikes barely 1000 miles for the valve adjustment but may try that too if all fails.

 

When a bike is slow to return to idle it usually means you're rich on the idle circuit. Turn your idle mixture screw in some.


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I did that already but after the idle goes too low and engine dies. Re start the bike, increase the idle and is fine. After I rev it, the idle stays high around 4t rt pm then comes down after like 30 seconds. Sometimes a minute , sometimes never.