2009 yz250f runs for 2 minutes and shuts down

casilio09yz250f · 08-15-2011, 08:50 PM

okay i got a 2009 yz250f thought it might have been the valves needed shimming had them checked and they were fine. fuel air mixture screw is fine cause when it runs it runs good then it starts breaking up bad and bogs down till it dies. then wont start till it cools down. then it starts first kick and will do the same thing? spark plug has been changed and does the same thing? I am thinking its the CDI box? what you guys think?
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dirtbikecowboy · 08-15-2011, 11:44 PM

first things first. does it have a hot start. if so there should be a hose that goes from the the air box to the motor. make sure the hot start is off. then take the hose off of the motor. blow in it if u can blow air threw it. u shouldnt be able to blow threw it with the hot start off. if u can it is not working right and thats ur problem. hot start is a red knob that says pull. pull is hotstart on. push it in hotstart should go off. if it isnt that check ur tps.if u have one

casilio09yz250f · 08-16-2011, 06:48 AM

That is one of the things i noticed when taking the carb off to clean it is that the plastic threads for the hot start were pulled out. My hot start only looks like it threads into the carb thats it?

casilio09yz250f · 08-16-2011, 06:48 AM

o yea and TPS.? what is that?

james365 · 08-18-2011, 09:07 AM

tps throttle position sensor and maby chec the coil they sometimes die when they get hot and u could also try loosening the gas cap when it does it and see if there is a negative pressure in there ive seen caps not vent properly

jonghond · 04-02-2012, 04:57 PM

Sounds to me like you're bike is running on choke whole time"hot start on" and I have a yz450 with the same prob starts easy when its cold and has to be runstarted when its hot I changed my chokes and still had the same fuckup.the valves could be bent but then the shimming would be right and if I may ask who checked the shimming for you ? Some people just don't know what they do with a head the valve clearence needs to be perfect.and if you feel it starting to fuck around while you ride open the cap and see if it comes right if not take it to a mechanic the rest of the stuff you won't be able to check yourself

08-15-2011, 08:50 PM	#1
casilio09yz250f Join Date: Aug 2011 Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	2009 yz250f runs for 2 minutes and shuts down okay i got a 2009 yz250f thought it might have been the valves needed shimming had them checked and they were fine. fuel air mixture screw is fine cause when it runs it runs good then it starts breaking up bad and bogs down till it dies. then wont start till it cools down. then it starts first kick and will do the same thing? spark plug has been changed and does the same thing? I am thinking its the CDI box? what you guys think? [Only registered can see links. ]

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08-15-2011, 11:44 PM	#2
dirtbikecowboy Join Date: Aug 2011 Posts: 2 Thanks: 0 Thanked 0 Times in 0 Posts	first things first. does it have a hot start. if so there should be a hose that goes from the the air box to the motor. make sure the hot start is off. then take the hose off of the motor. blow in it if u can blow air threw it. u shouldnt be able to blow threw it with the hot start off. if u can it is not working right and thats ur problem. hot start is a red knob that says pull. pull is hotstart on. push it in hotstart should go off. if it isnt that check ur tps.if u have one

08-16-2011, 06:48 AM	#3
casilio09yz250f Join Date: Aug 2011 Posts: 3 Thanks: 0 Thanked 0 Times in 0 Posts	That is one of the things i noticed when taking the carb off to clean it is that the plastic threads for the hot start were pulled out. My hot start only looks like it threads into the carb thats it?

08-18-2011, 09:07 AM	#5
james365 Join Date: Jul 2011 Posts: 28 Thanks: 3 Thanked 0 Times in 0 Posts	tps throttle position sensor and maby chec the coil they sometimes die when they get hot and u could also try loosening the gas cap when it does it and see if there is a negative pressure in there ive seen caps not vent properly

04-02-2012, 04:57 PM	#6
jonghond Join Date: Mar 2012 Posts: 7 Thanks: 0 Thanked 0 Times in 0 Posts	Sounds to me like you're bike is running on choke whole time"hot start on" and I have a yz450 with the same prob starts easy when its cold and has to be runstarted when its hot I changed my chokes and still had the same fuckup.the valves could be bent but then the shimming would be right and if I may ask who checked the shimming for you ? Some people just don't know what they do with a head the valve clearence needs to be perfect.and if you feel it starting to fuck around while you ride open the cap and see if it comes right if not take it to a mechanic the rest of the stuff you won't be able to check yourself

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