#8 04-30-2011, 01:05 PM bbrmotosports. Reset the idle speed back to the normal 2200-2400 rpm. Fuel screw settings in the 'book' are recommended starting points. Makes life easier when you can just set it from notes Vs. going through the procedure again. settings of 2 1/8 turns out. Any other ideas , please let me know. The engine should pick up speed and begin to smooth out. The idle should be smooth and consistent. My yz250f wont idle. Refer to your owner's manual for specific details regarding recommended idle speeds and adjustment methods. Start the … It's in the front side and it's a large straight slot screw. Setting the Pilot Jet / Air Screw begins with having the motor at operating temperature. Would idle at a high rpm after turning the throttle. After warm up, set the idle speed about 500 rpm higher than the normal 2200-2400 rpm idle speed. Keep trying 1/4 turn out at a time. OR you could set it at 1 1/2 turns out from seated in position. Restart it and slowly screw it in till you can just perceive a change. Once you get the bike to start turn your idle screw up to keep it running and let it get warm. Took apart and cleaned the bottom half of carb. Gently turn the screw all the way in. The idle adjustment screw on a 400EX is on the left side if the carb. Adjust the spring AIR SCREW in 1/4 turn steps in/out until the maximun idle speed achievable is found. I cleaned mine a while back and was told by a Yamaha mechanic who looked it up in a book he had to set the idle mixture needle valves at 1-1/2 turns from seated as a starting point and adjust from there. My 2003 yz250f will not idle with choke off. View and Download Yamaha YZ250F(Y) owner's service manual online. YZ250F(Y) motorcycle pdf manual download. ... IMHO, if it isn't a simple fix like an idle screw adjustment then I would take it back to the dealer and have them take a look at it. if you want to slow the idle down, back the screw out. Page 1 of 2: 1: 2 > All Things Moto! MtnEX. Started up the YZ to do some troubleshooting with the idle. Counterclockwise lowers the idle. First, turn in the mixture screw until the engine dies or runs worse, then back out the screw (recommend turning ¼ to ½ turn at a time). Still having same problem. the most beneficial mod i ever got for my bike was the service manual. Set pilot screw back to Fac. *** Turn the screw in until the idle becomes rough or the bike stalls. if it stalled, open the screw about 1/4 more turn. Dirtbike Forums > Dirt Bike - ATV - Suspension Forums > 4-Stroke Dirt Bike Bike Forums > … Do it with the bike fully heated up. Also for: 2009 yz250f, 2009 yz250fy. If you turn it clockwise it will increase the idle. I'm gonna turn pilot screw in and see if it makes a difference. Every bike is different, as is the temp and altitude. That may get you started. The first thing to do is not set up the idle speed, but to set the Idle mixture screw to lean best idle setting. 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