ATC Throttles down slow?

[MPDano]

Hello all,

Was wondering what could cause the throttle come back down to idle slow? Is it air/fuel screw adjustment? Vacuum leak somewhere?

Any suggestions?

Thanks,
Leo

[shortline10]

About a dozen things can cause that issue . Clogged small jet , intake manifold leak , worn or in properly adjusted throttle cable . Depending on the type of carburetor it could be a choke plunger issue , air screw adjustment, worn throttle valve .
Gas cap not venting correctly, clogged petcock , float valve . If it's a two stroke it could be worn crank seals
Start with cleaning the carb and go from their .

[jb2wheels]

Generally indicates a lean condition.

Could be an air screw adjustment or vac leak as suggested.

Any recent changes to the system?

[yaegerb]

likely an air leak

[MPDano]

Agreed on the air leak. Carb was rebuilt a couple months ago from a non running ATC250SX. New Petcock, line and filter. I'll try to richen it up a little first to see if that helps.

[barnett468]

Agreed on the air leak. Carb was rebuilt a couple months ago from a non running ATC250SX. New Petcock, line and filter. I'll try to richen it up a little first to see if that helps.

Make sure the slide returns easily all the way to the closed position.

You can gently spray flammable brake cleaner using the long nozzle that comes with it around the carb boot where it meets the head and where the carb enters the boot when the engine is idling . If the rpm increases while doing this, it has a leak in this area . Try not to breathe the brake cleaner fumes, however, contrary to what some claim, in this type of situation they will not kill you . Also check to see if the slide feels very loose in the carb . The carb and slide can can get worn and cause idle problems.



PREVIOUS KAWASAKI INTERNATIONAL R & D PROJECT ENGINEER AND ATV DEPARTMENT SUPERVISOR

[El Camexican]

Not likely your issue, but a big thumper engine can pull hard enough on the slide at higher RPM to cause it to over power the return spring and stay open. That's the reason for return cables, or push/pull set-up on some carbs. If not for that the return springs would need to be so stiff that your right arm would tire opening the throttle.

[MPDano]

Guys, forgot to add this is a 250 4 Stroke carb.

[Rob Canadian]

How slow does it come back to idle? IMHO I would look into the mechanical side of things first. How does the the slide return.
Engine not running. Does the slide go up and down freely from the thumb throttle response. Yes you would have the remove the boot to the carb as you would know. Should be instant. Open/close...

This eliminate some stuff. Binding in the cable ETC.

[Stingray]

Check the throttle cable routing and see if there is any binding while moving the cable position a bit

[MPDano]

Gave it about a 1/4 counter clock to richen and this seemed to get it to idle down correctly. Thanks for all the advice guys!