tach problem

finally got my bike started today and now im on to the next problem :roll:
runs great fire fight up and all but makes a noise in the top end. i also noticed my tach seems off. when i rev the engine it is way behind. it will read rpm but it is way off. i think maybe the drive is the noise(i hope). when i disconnected it from the head the noise remained. im wondering if the drive inside the head could be the culprit? anyone have any experience with this?
im gettin there!!!

 

It's certainly possible; have a look: http://xjbikes.com/Forums/viewtopic/t=19538.html

A description of the noise might help; as would some more info like the mileage on the bike, some basics about its history, etc.

 

thanks fritz. i have a feeling its somethin to do with the drive (#1in the drawing). the noise is like a gear not completely engaged, like a fast clicking sound. figured it was cam chain type noise but with tach acting up hopefully its not. its got 30k miles on it. just bought it not running, changed a lot of electrical stuff to get it to start. fires right up and runs fine so doubt its to serious yet. will tear that tach drive out today and hope to see a striped drive gear. cross your fingers lol