strange new noise

[breezeair]

my bike has about 600 miles on it now. i have started to notice that when i ride hard in first on second gear, i mean full throttle or very close to it and slam the throttle shut i can hear a knock, kind of like a hammer on metal sound. the motor is still oem, fmf gnarly, carb is tune very well and it runs great. any ideas?

 

[bradf]

Sounds like a momentary rich bleed-over condition, or in other words it is unburnt fuel igniting in the pipe. Check the float level and even though the manual says 16 mm, set it to 18 mm.

 

[KDX CRAZY]

Just a thought , maybe check your chain tension . The OEM chains are rubbish and stretch every ride , it could be hitting somewhere .

 

[COMBEN]

Short Shifting?

If you are short shifting the gearbox (changing up early, when you are riding lazy) every 220 I have had makes this noise..... it's something to do with the chain running around the front sprocket in a not so tight manner I think?

...in fact it isn't only KDX that can do this my mates KTM-525 does this too and my KX-125 used to!

 

[KDXLance]

I have recently leaned out the jetting on an 06 kdx200 and my bike is now making similar noise to what you describe when I throttle off. Maybe a little lean somewhere? 45/155 mid clip stock slide.