YFZ 450 hot cutting out

[yfz45006]

I have a 07 yfz 450 engine that i bought. i have been haveing problems with it cutting out after about 1 to 2 laps on the track and once it cools down it runs the way it should but when it gets to a certain temp. it just keeps cutting out. i heard it could b a coil so i put a new coil in it and didnt fix the problem. i have heard it could be the valves need adjusted, the stator could be going bad i just cant find it if anyone would have any solutions i am all ears thank you

[yfz45006]

I have a 07 yfz 450 engine that i bought. i have been haveing problems with it cutting out after about 1 to 2 laps on the track and once it cools down it runs the way it should but when it gets to a certain temp. it just keeps cutting out. i heard it could b a coil so i put a new coil in it and didnt fix the problem. i have heard it could be the valves need adjusted, the stator could be going bad i just cant find it if anyone would have any solutions i am all ears thank you

[Mikey Antonakakis]

What exactly cuts out? Do you have no electric power? Is everything working but the engine not running? Are certain things turning off?

[yfz45006]

The engine just shuts down and wont fire back up until it is cooled down. I disconnected the teather cord and it still has the problem. it is just the engine shutting down i dont know if it is a fuel issue or an electrical issue because everything checks good when it is sitting

[Drew Price]

Do you have any way to check the electronic signals when it's running?

Does your '07 have electronic ignition control? Is it running a standalone, or the Yammy carb?

It's very common for cam/crank position sensors to fail only when hot, then work when cold (goes for your street car too).

See if you get an RPM trigger to the ignitor when cranking once it's heated up and stalls out, if not try replacing the sensors and see where that gets you. Maybe some sort of generator or regulator failure too?

Easy way to check is as soon as it does, pull the plug wire stick in a test plug and ground it out, see if you are getting spark or not.

[yfz45006]

There is no crank or cam sensors on this engine and it has a carburator. one thing i have toolked into is that the thermo sensors have gone bad and arnt turing the fan on and letting it over heat and shutting it down before it seizes. but i am still on the hunt for this problem

[Mbirt]

Your YFZ450 does have a crank position sensor which the CDI unit uses to know when to provide spark. So check and make sure it has spark once it dies. If not, it could indeed be the crank position sensor. The 450's are also quite sensitive to valves going out of adjustment, so make sure your lash is within Yamaha's spec.