Could be the cam chain/tensioner.

 

Rattle

Hi I just had my break in service done with valves being ran, if I crack the throttle hard, around 25 mph it has a slight rattle in mine? I just put around 98% of the time, until I have had a few to many, then raise a little cane, I just assumed the motor is still a little tight, about 200 miles on it now.

later

 

My 05 did that too. I think it's just the noise that the tranny makes at high speeds. It bugged me too until other Ruby riders had the same noise.

 

the big question is?? is it smoking??? if so i would guess you have bad rings. If not i would probably check the timing chain.

 

I have a little topend rattle in my 05. I was told by a Honda mechanic (personal friend) that the Rubicon motor is a noisy motor. Not as quiet as the other Honda motors. So far, it hasn't come apart.

 

No it dont smoke i just jut a oil pump chain on it. The timein chain looked good. But seeing what alot of yall are sayin uv heard the same noise or some of yalls are doin the same thing. As long as im not the only one.