arossitt

Member
Apr 22, 2001
30
0
I have a strange rattle in my motor,sometimes it almost is undetectable.Is there some way to tell if it's the rod small end or piston slap,I am half convinced it's one or the other.Thanks in advance.
 

Shaw520

Damn Yankees
LIFETIME SPONSOR
May 14, 2000
1,082
6
What year is the bike?, does it have alot of hours on the engine? The cam chain can make noise that sounds like a rattle, indicating it has reached its service limit.
 

SFO

LIFETIME SPONSOR
Feb 16, 2001
2,001
1
If the bike has been caned they will frequently stretch the small end and start rattling.
 

Humai

LIFETIME SPONSOR
Feb 6, 2000
199
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General rattle detection guidelines:

Small end rattle: Usually heard more at light throttle transitions, idle or deceleration. YZ400Fs are noted for this type of noise.

Piston Slap: On a four-stroke, it is power related; that is, the stronger the engine fires, the more piston slap noise is produced. Usually more evident at lower revs, just off idle. KLX300s are famous for their "klack klack klack..." piston slap noise at lower revs.

Timing chain slap: Is often louder when the engine is cold and is not affected by power on/off transitions. It is often loudest at idle and reduces with revs. Worn neglected XR200s can often make this type of noise.

HTH
 
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