'03 Yz450f TPS/IDLE/Cutting out Need Help

6 replies to this topic
  • DHenson

Posted April 03, 2006 - 11:17 AM


My '03 450 is acting strange. Several weeks ago i was having cut out problems and erratic idle. I discovered that the fuel screw fell out. I replaced the fuel screw with a zipty screw. I set it at about 1 1/2 runs out. It starts but dies after 4 seconds. Adjusting the idle only makes it idle higher before it stops. Here is what I have done to date:

1, Cleaned Float Bowl,
2, Removed and replaced the Fuel screw tried stock and Zip Ty.
3, Replaced Spark Plug
4, Check TPS Resistance (out of spec) the resistance was at 3.8kOhms at full open spec is between 4-6kohms.
5, Unplugged TPS, (only tried to kick it a couple of times).
6, Replaced Air filter, both old and new are Twin Air filters.

Nothing seems to resolve the problem. Please note I have a Rekluse clutch and stock flywheel, these have always worked in this configuration, any help would be appreciated.

  • Chas_M

Posted April 03, 2006 - 11:48 AM


A sometimes overlooked point is to make sure to include the small washer and O-ring at the tip of the fuel screw.

  • DHenson

Posted April 03, 2006 - 12:09 PM


yes, I was sure to install the spring, washer and then oring. I also checked to be sure that there was no contamination in the port prior to installation.

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  • DHenson

Posted April 03, 2006 - 04:41 PM


Continued troubleshooting,
Removed the Kill Switch no affect.
Removed the TPS no affect.
Checked the Tank vent line, no problem.

It will run at higher RPMs if I crank up the idle. much too high for riding, it backfires when I kick it on occasion.

Any help is appreciated.

  • new2blu

Posted April 03, 2006 - 04:59 PM


Have you checked the adjustment of the valves? When they get out of spec it will start hard when cold, and can sometimes have a hanging idle. It is possible that you have a vacuum leak.

  • DHenson

Posted April 03, 2006 - 05:04 PM


Thanks I will look into that, I just had the valves checked several months ago when i replaced 4th gear but I have heard of the exhaust valves tightening up. I'll check for leaks as well thank you.

  • One Louder

Posted April 03, 2006 - 10:08 PM


Did you tear the carb down and clean everything? maybe the pilot circuit has some crap in it :thumbsup:

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