Exessive engine noiseThe motor has to come out of the bike and the top end torn down to replace the cam chain. A couple of points here... If the cam chain needs to be replaced, I would tear it down anyway to have a look at the rings, valves, etc. I would consider replacing my mechanic too if he were asking these kinds of questions...
New mechanicI agree with 48. If he can't look at your bike and tell you that the motor needs to come out to get at the timing chain he may not be the right guy.
BTW How did he decide that your cam chain was the culprit?
He found that the chain tensioner was as tight as it can go yet the noise persisted. He already adjusted the valves. Not sure what else. He told me he thought he might be able to take the gas tank off and take the engine apart while still on the bike but he was going to look into it more. I figured I'd help out by getting some info here.
Here is my problem "The cam chain tensioner is as tight as it will go". The cam chain tensioner isn't "tightened" it is a spring loaded device that is self adjusting when the tensioner lock nut is loosened provided the tensioner is not frozen which can be common on these bikes.
A loose cam chain would make a noise but definitely not any kind of "clunking". The tensioner assembly is very easy to remove and check. It is also very obvious that the top end of the engine cannot be removed without dropping it out of the bike. At this point I don't have much faith in this mechanic. Ask him how he determined the cam chain tensioner was at its max!! I would suggest that you and your mechanic read this before you spend those dollars....
http://www.scramblercycle.com/uploads/3 ... manual.pdf G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
He did explain that it is spring loaded. I'm trying to relay what he told me with my limited memory and mechanical know-how. All I really know is that he told me the chain is the problem. He did tell me why he thought it was the problem, I just have a terrible memory sometimes. I guess I may have misunderstood what my mechanic wanted to figure out exactly. Maybe he was concerned with having to take the entire engine apart. I know he's does well with anything that has a motor in it. That's for sure. He has a good reputation around my area with over 30 years experience. I trust him to do the job well as he's never let me or anyone I know down before. He's also a nice guy, so I think he might be trying to give me some hope that I won't have to pay a big chunk of money to him afterward. There's no clunking noise. Just a loud rattle. I did put new spark plugs in it and that stopped the other issues I was having. New plugs haven't fouled yet either.
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