Rpms take a couple seconds to drop back to normal after being riden for a while

[XSnoob]

(xs400 2e) starts up real good every time, and rides very smooth.The rpms drop back to idle nice and quick for the first 20 minutes of riding.

After about 20 - 30 minutes of not very hard riding around town, the rpms start to take longer to drop back to idle, which i keep at around 1.3k. Ill blip the throttle up to 3k and it will slowly drop, takes up to like 5 seconds sometimes.

Wondering if anyone else had similar issues and figured it out. Im thinking its an air leak in the air intake boots but not sure. I just got new carb intake boots the other day.

Can an air leak happen through the air filter box case? theres only 1 screw holding it together rather than 2, on both air boxes.

I dont think its a fuel mixture problem because the bikes rpms respond great when the bike isn't at higher temps.

Is there anything else I'm missing?

 

[XSnoob]

Any one?

Bikes still doing it, can't figure it out, Rpms take longer to drop back to idle when the bike is hot.

 

[16VGTIDave]

The lack of response is due to this being covered many time in many threads.

To sum up the possible solutions:
- Find any vacuum leaks between carbs and head and fix.
- Clean your carbs, then clean them more.
- Check the valve clearances and adjust if required.
- Adjust pilot screws richer, your idle mixture is probably lean.
- Sync the carbs.
- Use the search function...

Dave

 

[xschris]

Could also have a small hole in one of your diaphragms, or loose from the slide(able to spin on it).