Ive had a klx 300 for but 3 months wanting something to get into trail riding so thought the 300 would be a good start researching my options . after a few rides it got harder to start then the last two times i took it out it had to be tow started {not good i know}since then after finding kf and looking at a few tips from you awesome people on other membes posts i thought it was the shims . ive pulled the cam cover off and tried to check the clearances but there was none at all on the inlet so pulled inlet cam off and investigated the shims to find that the shims had been ground down and there are no numbers on them ,the other thing ive noticed is the left hand valve stem sits up higher than the other . The other thing i found is the ADC has been welded , why not sure .
So if any one can help would be much appreciated .

 

Your specified clearances are, intake 0.10 to 0.19 mm and exhaust 0.15 to 0.24 mm. Since you do not have any clearance you need a thinner shim. You are going to have to make an educated guess as to what size you need. Use a set of Micrometers to measure the ones you have (some read in both thousands and millimeters) as a starting point. The fact that you can see a level difference in the top of the valves would indicate to me that you have a problem that means you have to rebuild the head and put in new valves. Also the fact that your ACR has been welded indicates someone made some modifications which need to be undone. After you get the head back in working order you had better check the idler gear in the kick start mechanism to make sure there is no wobble. If you damage this assembly you run the risk of major engine damage.