#1: Knocking, Tapping In Top Of Front
Cylinder (SOLVED) Author: 1986 XV700, Posted: Sat Aug 28, 2010
1:06 am
This post started out as a
question until I decided to check my valve clearance "just one more time."
I'll go ahead and tell you the problem wasn't valves, rocker arms or cam.
My bike decided to join the front cylinder knocking club yesterday
morning on my way to work. For the past year or so its had a persistent
light tapping sound that would occasionally get loud on deceleration but
usually what might be better described as a tick. This evening I decided
to figure out what the problem was since it was now embarrassingly loud
and really had me concerned.
I checked all the normal things one
would check: Oil Level - Good. Valve Clearance - It was out pretty
bad but proved not to be the problem after I corrected it. Rocker Arm
Play - There was a little side to side movement on the shaft but there
wasn't any movement to make me think the pivot hole was worn. Oil
Flow/Pressure - Cranked up the bike with the front intake valve cover off
and oil splatter everywhere and puddled on the floor.
When I
cranked the bike with the valve covers off I also had the cam cover off. I
looked in at the rotating cam end and noticed the chain slapping the
cylinder head in rhythm with the tapping sound. Now it was clear the chain
tensioner must have a problem right? It did, would you like to see it?
Before you look I'll tell you what I found and how I fixed it.
The
problem was one end of the clock spring was no longer connected to the
tensioner housing and therefore couldn't apply proper tension to the
tension pin. From what I could tell the fixed end of the spring was
supposed to be in a hole that is partially drilled in the side of the
spring cavity. I heated the fixed end of the spring and formed a hook in
it that would fit into the cavity. Because I wanted it to stay put I
wedged it into the hole with the hollow aluminum portion of a 1/8" pop
rivet. The rivet isn't "set" just gently tapped in to keep the spring in
place.
Before winding the spring into place I twisted the tension
adjustment pin to the left tightly to keep it in place and hold the
tension pin fully extended. I was then able to twist the tensioner
housing, winding the spring into the cavity. Once wound into the cavity I
put three additional twists on the spring to supply tension to the pin
while extended. The cap was bolted back into place and I retracted the
tension pin by twisting the adjustment pin tightly to the right so it
would stay put. After installing the tensioner back into the engine a
slight left twist on the adjustment pin and I heard it zip back into
place.
I restarted the bike with the cam cover still off and it
actually sounded better than a sewing machine. A sewing machine ticks, my
bike don't. Yeah baby, the sweet sound of success!
Here's a few
pictures of the disassembled tensioner: |