[jw450r1]

So my freind has a crf 450r with trail tech lights. We just replace piston and rings, new k/w valves cut seat in head.bike runs good until it warms up.when you try to start it warm sometimes it will not start.....
cleaned carb , recheck valves all within specs.
any ideas would be a help.

[jw450r1]

Also when it doesnt start (warm).I do have spark.but it ls more like a yellow spark.is that color normal?.also rechecked my timing mark and there on the money.....also when its running cold .when I pull in the hot start the motor dies down.so I think its working......

[JimDirt]

When it s hot will it do anything with the Hot Start pulled ?? , sputter , anything ?

[jw450r1]

It sometimes want to start, but doesnt

[JimDirt]

I am slightly concerned about the Trail Tech Stator , it might be causing this issue , because the spark should be blue and snap when it sparks (the snap sound you get when you get static electricity when you touch something)

A yellow spark could indicate a weak spark plug boot , a weak coil , a weak stator, or the CDI can also break down when it gets warm , i assume you have a manual , so you need to start checking the stator output (not on the lighting coil but for the ignition wind , it should put out what the manual says even if its a Trail Tech as far as i know ,you also might call Trail Tech (or email them) and see if they have any specs to give you that might be different from OEM


The only carb issue it could be would be incorrect jetting for your elevation , or clogged jets , but usually a clogged pilot (low end power) would have a lot of popping out the muffler , and you did not mention popping on deceleration , so i am still leaning towards a ignition issue

Where in Idaho are you located ??

[jw450r1]

Ok thank you for the info.....