Posted by William on May 23, 2010, 11:59 pm
Hi, I have a 79 Yamaha 650xs. I have a clatter I believe may be from a
stretched cam chain but not sure. When tuning up the bike the
adjustment for the cam chain tensioner is supposed to be done first. I
removed the nut and set the adjusting rod on the tensioner to flush
with the outside edge of the adjuster as stated in the manual. When I
started up my bike it sounded like the chain was clacking so I screwed
in the adjusting screw until the clacking stopped. When I stopped my
bike the end of the rod was about 1/8" sticking out, no longer flush.
The noise was similar to tappet noise but much louder. I did adjust
the valves twice on a cold engine and they are perfect. The timing is
right on too. I noticed that the clacking got worse when I slowed down
the idle to very slow and improved a bit when I set the idle higher.
Anyone have any thoughts on this. Am I heading for a major tear down?
The bike has 18K mile on it. I am the original owner. Anyone with any
information to share would be welcome. Thanks in advance. I have
search the net but cannot find anyone who has posted similar
symptoms....Willard
Posted by Klaus Hellnick on October 9, 2010, 5:40 pm
On 5/23/2010 10:59 PM, William wrote:
> Hi, I have a 79 Yamaha 650xs. I have a clatter I believe may be from a
> stretched cam chain but not sure. When tuning up the bike the
> adjustment for the cam chain tensioner is supposed to be done first. I
> removed the nut and set the adjusting rod on the tensioner to flush
> with the outside edge of the adjuster as stated in the manual. When I
> started up my bike it sounded like the chain was clacking so I screwed
> in the adjusting screw until the clacking stopped. When I stopped my
> bike the end of the rod was about 1/8" sticking out, no longer flush.
> The noise was similar to tappet noise but much louder. I did adjust
> the valves twice on a cold engine and they are perfect. The timing is
> right on too. I noticed that the clacking got worse when I slowed down
> the idle to very slow and improved a bit when I set the idle higher.
> Anyone have any thoughts on this. Am I heading for a major tear down?
> The bike has 18K mile on it. I am the original owner. Anyone with any
> information to share would be welcome. Thanks in advance. I have
> search the net but cannot find anyone who has posted similar
> symptoms....Willard
Tension the chain again. Make sure you rotate the crank at least 2
revolutions.
Also, detonation can also sound like a loose chain.
Verify that you have the correct plugs. Look for signs of damage.
Lastly, be very careful when using any sort of fuel additives, like STP.
Use no more than 1/4 bottle to a full tank.
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> stretched cam chain but not sure. When tuning up the bike the
> adjustment for the cam chain tensioner is supposed to be done first. I
> removed the nut and set the adjusting rod on the tensioner to flush
> with the outside edge of the adjuster as stated in the manual. When I
> started up my bike it sounded like the chain was clacking so I screwed
> in the adjusting screw until the clacking stopped. When I stopped my
> bike the end of the rod was about 1/8" sticking out, no longer flush.
> The noise was similar to tappet noise but much louder. I did adjust
> the valves twice on a cold engine and they are perfect. The timing is
> right on too. I noticed that the clacking got worse when I slowed down
> the idle to very slow and improved a bit when I set the idle higher.
> Anyone have any thoughts on this. Am I heading for a major tear down?
> The bike has 18K mile on it. I am the original owner. Anyone with any
> information to share would be welcome. Thanks in advance. I have
> search the net but cannot find anyone who has posted similar
> symptoms....Willard