mine is definate knock once its gets warm i wiped the head of last night there is no play in the big end or small end the piston is quite tight in the bore i carnt get fela guage down past the rings the bore is spot less no marks are sign of wear it all looks pretty good yet it still knocks quite loud it even run nice with plenty of compresion .so could it be fuel, jetting, where i live theres no trials shops are any one with any real knowledge of this type of bike so im at a total loss .so what jetting would any one recomenden!!