Engine noise

[Johnniespeed]

Yes thats the first one to break, my bike was about two weeks old when I heard a rattling noise. Fearing a reweld breaking over and over, I made a simple bracket that bolts to the frame under the radiator mounts. Even that cracks every two years, but is super simple to make from sheet metal.
 My guess is your broken frame mount is making noise. Fix it good either by welding or a bracket, then recheck for noise.
 Keep us posted on your progress. John

[martinfan30]

In the beginning of this video, right after he starts it.... You can hear the noise I refer too. Is this normal? You can hear it 
above the exhaust note.

http://www.youtube.com/watch?v=JIjgbScDmBw&feature=PlayList&p=F5269958E4E4EA74&playnext=1&playnext_from=PL&index=1

[Hillclimb#42]

 Check exhaust springs. While running see if you can pin point and put some pressure on different spots to find it. It sounds like something vibrating. Probably a pipe deal. Sometimes a kicker will make noise. I noticed a difference in my bike's sound with a new pipe, especially during break-in without a helmet. My noise is the spring laying on the pipe plus the pipe vibrating. Burnt my finger on the discovery, but was worth the peace of mind.

[KXcam22]

Funny but after owning my K5 for 14 years I never once broke a pipe mount (or anything vibration related).  Another source of noise can be the copper crush washer (that pads the pipe end from the clinder) is worn or the o-rings on the exhaust spigot can be worn out.  The worn crush washer will make some big rattles. Cam.

[martinfan30]

All springs in place, new pipe o rings and copper washer.

Cam, did you hear the noise on the video?

[martinfan30]

I am not gonna worry about it, because every video on youtube of an idling KX5  all have the same noise.

[tharden]

I really think you are just hearing the power valve.  I really do not see anything else really making that kind of noise.  Take a stethoscope and find out where the noise is comming from.

[KXcam22]

Martinfan,
  I did not hear the noise on the video.  Everytime I hear a KX500 idleing on utube I get all misty-eyed and have to go find a tissue.  Sometimes 4-strokes just don't cut it. Cam.

[doordie]

KIPS-rattle.....
Some shims and problem solved!