help? knocking sound.
Posted: Wed Jul 05, 2000 3:02 pm
I have a most perplexing problem with my 1988 KLR650 (19000 miles). When I
get up to about 50 miles per hour a fairly loud knocking sound starts and
gets worse the faster I go. I have been trying to troubleshoot this problem
for weeks now and I have found out a lot of things I think it IS NOT, but
the problem persists. At first I thought it my be a loose rod, but it does
not seem to be related to engine RPM. I can put the rear wheel up on a
stand, put the bike in 5th gear and rev it up to 4Krmp with no knocking
sound at all. Also, I can get the bike going down a hill at about 60 miles
an hour with the sound very prominent. If I pull in the clutch and let the
engine RPM fall to idle (1000rpm) the sound does not diminish at all. When
the speed starts to fall below 50 the sound fairly quickly disappears. This
sound started not too long after I put a new sprockets and chain on; the
front sprocket is oversized by two teeth. So, I though this must be the
source. But again, putting it up on stand a revving produces no sound. I
even removed the front sprocket cover and all of the chain guard assembly,
and this made no difference in the sound. It is very difficult while riding
to determine the location of the sound although If I lean over the tank I
can't hear it until I sit back in the normal riding position. Could this be
a worn cam chain that can no longer be adjusted? I have also thought that
maybe its a bad water pump?? If anyone has any ideas about this, please
send them along. This is driving me crazy and I have a long trip planned in
about a month which I will be reluctant to take if this problem persists.
Jim Cunningham