my uncle ownes a 250 recon think it is 01 but not positive and it has been babied since he bought it new he has barely used it until i bought my bike hes alays taken care of his bike but the last few times out hes noticed a loud knocking sound he thought it was something bumping around on the bike but today he switched to synthetic oil and its more dominant now and its definately coming from what i think is the upper half of the motor i suggested bringing it in for a valve adjustment its never been done since he bought it since he cares for it himself any one got anything were heading out tomorrow and hes concerned of blowing it up thanks for your info

 

OK hears how I check for the difference between a knock and a valve clearance problem. Start and put in gear hold the brake and slowly rev up the motor, if the noise gets louder then it's crank or piston noise. If it stays the same or stops then it's valves. I have a 2001 250 ex and it has a knock when it's cold. I have rebuilt the motor and know that it is all good. I called Honda on these casue I have heard this on other models (250's) they never hade any complaints. I have figured that mine is the clutch basket on mine that is worn and making that noise.