Valve Adjustment the DIY Way !!!
I recently did my very first valve adjustment on my ZRX that I bought used
and had no good idea when they were done last. The bike has 33k. I did a lot of
research before starting - found some good info but there were still some things
that could have been better, so I decided to take some pictures and do this
Taking off the gas tank was easy enough. I did not drain the coolant. I
opened up the bolt that holds the thermostat housing on the left side of the
bike and pulled the whole thing up, out of the valve cover's way. I pulled the
upper coolant hose off and zip tied the other out of the way.
Once the hoses and wires were out of the way I pulled off the
valve cover from the left side. Needless to say you have to be careful with the
rubber gasket so as not to break it. I took the spark plugs off and stuffed rags
in the holes to prevent anything from falling in.
There are spark plug cover seals around the spark plug holes, be
careful not to tear them. I ordered replacements for mine as they were kind of
hardening. Dipped them in oil before putting them back in.
I measured the clearances between the shim and cam lobe with the
lobe pointing 180 degrees from the shim. I rotated the cams by the rear wheel in
5th gear. The rags in the spark plug holes keep popping out when you rotate the
engine due to compression so keep an eye out for them. Having a head lamp or a
light hand really helps when looking into the engine and taking measurements.
I wrote down all my measurements and removed the shims that were
out of spec or too close to being out of spec. I removed the shims by sliding
the rocker arm sideways (they are spring loaded) and using a cheap extendable
magnet thingy I bought for a few bucks at Autozone. The shims come out fairly
easy. Shim diameter is 9.48mm. I measured each shim for thickness. Did not want
to rely completely on the numbers printed on them.
I wrote down my measurements on my valve sheet and taped each shim I took out in
the respective place on it. Completed my calculations on the computer and
figured out if I could re-use any shims I had. I was able to re-use 8. I ordered
a refill kit for the rest - $35.00 on ebay. It came with 5 of each size. I just
needed to order 1 more to complete what shims I needed. Total spent on shims was
about $42.00 with shims to spare for next time.
Putting the shims back in can be tricky. I used some grease to stick the shim to
my finger and place it carefully on the shim bucket. I fine tuned the setting
using a small screw driver. You have to be careful not to apply too much
pressure so you do not scratch anything. Once they are in the right way they
will slide in the bucket real easy.
After putting the shims back in I re-measured the clearances to be sure I had
them in right. Double and triple check that everything is in there properly
before closing the valve cover. I cleaned off any dirt and grime from the valve
cover contact patches and used some RTV silicone on the cover. Tightened
everything back up and let the bike sit for 24 hours before starting to let the
silicone dry completely.
Came back the next day - started the bike and took it out for a ride. Runs like
a dream and I know I done it right.
So, all in all - valve jobs are easy on the ZRX. Take your time and get your
One more thing - I have read not to rotate the engine with shims out - I don't
know why ? I checked with my buddy who is a certified motorcycle mechanic and
owns his shop, he said it makes no difference. I rotated the engine with the
shims out and have had no issues at all. I made sure to move the rockers back in
their place before rotating though. Any insights?