Those who know me well are aware of my fondness for the
Kawasaki W650 models, which were only sent to the US market for two years
(2000-2001). I have owned three of them over the past 9 years, with two 2000
models and the last one a desirable 2001. The 2001s had some subtle changes to
the front axle, steering head angle, rear fender and were painted a lovely
two-tone Dark Green over a Cream bottom portion.
Due to a plethora of bikes that have been coming and going
in the past year, I decided to let the 2001 bike go and advertised it on the
local Craigslist as well as once on eBay, but with no results. The bike only
had 9k miles on it, was all dialed in with carb jetting and suspension upgrades
and was driven briskly on Sunday mornings with my friends the Jamul-igans. With
skinny tires and forks, plus about ½ of the other’s horsepower ratings, the
bike was driven hard, but not abused. Previous crash damage was mostly all repaired;
leaving only a few spots of scrapes and paint chips. It put a smile on my face
every time I drove it, but it was a bit too big and ungainly for quick trips to
the local Post Office or auto parts stores. Historically, I don’t keep vehicles
much longer than a year or two, so the time was up for this fine machine.
Most of the Craigslist responses were scammers trying to get
my email address or phone number for nefarious purposes, but one reply came
from a man in Rocklin, CA (550 miles from Spring Valley) who was “ready to buy”
and even considered flying down and riding it back home. The only holdup on his
plan was that he was trying to sell his 1990 GB500 TT bike, which was somewhat
weathered and had 29k miles showing on the speedometer. The sales efforts were
non-starters for various reasons, so after we exchanged messages back and forth
for a couple of weeks, I decided that I would offer a swap; his GB500 for my
W650. He agreed to meet me “half way” between SV and Rocklin at Visalia, CA,
where my cousin has lived for over 40 years.
The photos of the GB500 were less than detailed, but I
figured that a licensed, running GB500 with mostly all original parts was equal
in value to what I was trying to get for the W650. So, one Friday morning, at
4AM, I launched my Toyota Tacoma up the I-5 with the Kawasaki W650 secured in
the bed. The plan was to get through LA traffic before it became unbearable
during rush (?) hour. I had agreed to meet up in Visalia at noon time, to give
us both plenty of time to arrive at the destination. Well, my plan was a little
too optimistic, perhaps, as I arrived some 300 miles from home at 9:30AM!
Texts from the GB500 man indicated that he didn’t leave
Rocklin until 6:30AM, which took him right into downtown Sacramento traffic at
7AM, so he was delayed quite a bit on his end of the journey.
In the meantime,
I spent time with my cousin who owns a thriving auto repair shop in Visalia and
is a real “gearhead” kind of guy, owning a couple of 1960s Mopar drag cars
equipped with Hemi engines, as well as an airplane and some pricey automobiles
and trucks. It was great to catch up with him during my 3 hour stay, but I
finally decided to leave the shop for the rendezvous near the Highway 99
Junction which was about 8 miles away. While I was driving, he sent a text
indicating that he had taken the wrong off-ramp and was turning around to the
intended location. As I came upon that same off-ramp, I looked ahead to see his
car (Honda Element) just getting back on the freeway. I went back on the
freeway ramp and followed him right to the Chevron station that we had agreed
upon as the meeting place. Good timing!
Yes, the GB500 came down in the back of a Honda Element SUV,
actually fitting in quite nicely. We unloaded our bikes, took a quick test ride
to confirm that this is what we really wanted to do, then swapped bikes into
each other’s vehicles, completed paperwork and headed off for home, once again.
I was a little disappointed with the overall condition of
the GB500, as the alloy parts were mostly corroded, however most of the chrome
plating was relatively clean. Apparently the bike lived in Oakland for awhile,
near the bay and was obviously ridden a great deal in the past 27 years, so
wear and tear is expected to a certain extent. My biggest concern was the
noises coming from the engine, as it was fired up cold. It was hard to pin down
the specific area of the engine where the noises were occurring, but it was a
bit unnerving to say the least. The bike ran fine on the test run, so I just
decided to go forward with the deal and fix whatever was necessary later on.
I ran back down the 99 to the I-5 junction, then up over the
Grapevine pass to the 210 highway junction, which I took to my friend Myke’s
place in Sunland, CA. The total mileage covered for the day was about 500, all in
13 hours. I enjoyed some rest and a nice Thai meal nearby and went to bed
planning on an early start on Sat morning, in order to miss the always busy
southbound freeway traffic headed into San Diego.
I launched at 6:30AM and headed way east towards the I-15
southbound, where traffic was racing along at 70-85mph, making the return leg
of 180 miles in 3 hours. I unloaded the bike, unpacked and then stripped the
tank off of the bike to see what was underneath the bodywork and perhaps pin
down the source of the engine rattle. With the help of S100 cleaner and a hose,
I was able to clean the bike up pretty well, followed by a blow-dry session
with the air compressor.
I checked the valve clearances, which were just slightly
loose and attended to an odd oil leak that was coming out of the center of the
rocker arm cover. The bolts for the cover are all supposed to be dry, so I was
able to squeeze a little 8mm o-ring over the bolt head (it was too long to
remove with the engine in place) and then retorqued the bolt, hoping for an effective
repair of that problem. I finished up by installing a fresh spark plug and
removing the rest of the pollution control devices and hoses which were
partially taken off by the previous owner.
Both tires were under 20psi, so I aired them up, checked the
oil level and the chain tension and headed out for a test ride around the
neighborhood. The bike ran well and was responsive to the throttle, but the
clamor coming from the engine continued to puzzle me. I decided to take the
GB500 on the Sunday ride and see if it would break something or if the noises
were just excessive piston slap on a 92mm wide piston, churning up and down
with a redline of 8k rpms.
Well, the Sunday ride went well and I thrashed it as much as
was reasonable under the circumstances. Unfortunately a prior owner installed
oversized tires on both ends, so a good deal of caution was taken not to get
them way out on their sidewalls. The tires are Bridgestone BT45s, which are
grippy things, but these were getting sidewall cracks due to age.
Back home, after the ride, I did research on the GB500 noise
problem and found a detailed webpage that described having to replace the
piston at 27k miles on his machine, plus he rebuilt the crankshaft with a rod
kit which is available. The engines are related to the early XL/XR500-600s, so
some of the parts will interchange. Supposedly, the 97mm XL600 piston and
cylinder will mount up on the GB500 cases, giving a 100cc displacement
increase. Other models use a 100mm piston, but that is probably really pushing
it, unless you do a full-on rebuild.
After the successful Sunday ride, I decided to drain the oil
and pull off the top end to see what might be causing some of the noises inside
the engine. Fortunately, the top end can be removed with the engine still in
the chassis. You can pull the head off and away from the
carburetor/manifold/air box with those components all safely in place.
The top cover has the rocker arms all installed and the
first bit of bad news was that both of the exhaust rocker arm pads were worn
down excessively. The good news is that the intake sides were all just fine.
The center of the cam runs directly on the cylinder head bearing, which is
oiled by an oil feed hole in the camshaft. The cylinder head side was scored and
roughed up like the exhaust rockers, but the top cover bearing surface was like
After figuring out how to extract the camshaft from the
sprocket and two ball bearings, the head was ready to remove. There didn’t seem
to be a lot of deposits or moist carbon on the valve heads or the piston crown,
as if someone had been in there before, freshening up the internals. Sure
enough, despite a lack of markings on the piston, the piston rings had .25
marked on the edges. The piston didn’t show any signs of distress or a great
deal of wear. The cylinder bore still had nice cross-hatch marks on most of the
surfaces, but when the rings were removed from the piston and stuck back into
the bore, the end gap was .025” to .035” on the two top rings. Normal specs are
about .012” to .016” using the standard reference of .0045 inches of end gap
per each one inch of cylinder bore. I had my machinist friend measure the
piston and bore size accurately and he determined that the piston clearance was
about .003” which is near the wear limit of .004” that Honda recommends. He
felt that the piston clearances were not sufficient to create the kind of
engine noises that I was hearing.
With the 24mm piston pin removed from the piston and
refitted to the rod end, it was evident that there was enough clearance to give
a loose rocking fit to the pin in the rod end. Most likely, this is the main
source of the engine noise. The remedy is to install a $125 rod kit in the
crankshaft, once the engine is pulled all the way apart and a machinist presses
the crank apart and back together again with the new rod kit. Not what I had in
mind for this little bike project.
The bottom end was pulled out of
the chassis and put on the bench for disassembly in order to replace the
connecting rod in the crankshaft. There are several locking nuts inside to
secure the clutch hub and other critical components, which needed a 24mm socket
and air wrench to remove. Once the locking nuts were removed, the rest of the
engine more or less melts apart into transmission and counter-balancer units
along with the huge ball bearing which supports the crankshaft in one case
While waiting for the arrival of
the connecting rod kit, cleaning and some painting was done to the top end
components, along with replacing the valve stem seals in the head. The valves
were de-carboned and the combustion chamber cleaned up of old burned oil
residues. The inside of the engine was quite clean, so regular oil changes must
have been done in the past 27 years. New gaskets and seals were procured via
the Internet, but it was surprising how few parts are left available for these
bikes now. A SoCal dealer had a new set
of .25 oversized rings, which when checked in the cylinder bore did show a
reduction in the end gap measurements over the old ones removed.
A local camshaft manufacturing shop
felt they could regrind the lobes without having to dig too deep into the base
circle (schneidercams.com) so they took the old
camshaft in for a couple of week wait in their queue. New OEM rocker arms were
purchased through the local Honda dealer, so the major pieces are coming
Because of the
miles on the bike, a decision was made to buy an aftermarket starter motor
repair kit and freshen up the starter motor before it was returned to the
engine cases. Once apart, there was very little wear showing on the brushes, so
the kit was left unopened and will go with the bike to the next owner someday in
still hung in the airbox, so it was an easy task to remove the throttle cables
and enrichener, loosen the clamp and remove the whole carb as a unit for
cleaning and inspection. In all likelihood the carburetor had never been serviced
as it was still jetted to the CA spec 142 main jet size. I didn’t have any
145-ish jets handy, so used my tapered jet reamers to open it up more towards a
148-150 size. With a fresh motor, use of alcohol-based gasoline and the
possibility of a slightly modified camshaft grind, a little more fuel is
generally a good step towards improved performance.
The crankshaft was taken to a local machinist
friend, who found difficulties in attempting to remove the crankpin from the
assembly due to a close-fitting sprocket pushed up against the crankshaft
cheek. Finally, he just pressed the easy side off and checked the pin for wear
and damage. The pin checked out fine, so the new rod was installed and the
crankshaft pressed back together again. Finally, he had to gently press the
crankshaft back into the engine case half to complete the job.
crankshaft done, assembly work could resume and all the little bits and pieces
reinstalled where they belonged.
I had the unfortunate experience of buying an
“Engine bolt kit” from an eBay seller which appeared to be a complete kit, but
was found to be missing the crankcase bolts. Emailing back to him was
frustrating as I was told that if I had “read” the details I would have seen
that the crankcase bolts were not a part of the “kit” and were available at an
extra, undefined charge. This was all buried in a dozen paragraphs once you hit
the “SEE DETAILS” section. Why he chose to offer a “kit” without the critical
center case bolts is a mystery and he never would say why he did it or why he
didn’t list the price of the extra bolts in his auction. After some unpleasant
exchanges, I paid an additional $25 for a handful of bolts, which the seller
then cancelled and decided to block me from future business, leaving me without
the final matching bolts to finish putting the engine back together with.
on eBay did offer the center case bolts as part of their main kit, but I only
needed the few not a whole kit. His main website offered individual bolts and
fasteners in an easy to use menu, so I ordered up what I needed from there and
awaited delivery. It was a very frustrating experience to say the least and has
held me up an extra week, just because the seller decided to play games with
his product offerings.
In the meantime,
the front brakes were addressed with a caliper rebuild, new pads and a fresh
master cylinder kit installation. New BT45 tires were spooned onto the rims and
fresh rear wheel dampers installed in the rear hub.
weeks, the cam grinding company discovered that they couldn’t grind the cam
lobe next to the de-compressor parts attached, so took it to a nearby machine
shop which took 2 tries to get the end pieces pressed off. Apparently they only
had an arbor press not a hydraulic one. They finally get it loose, with the
bits flying all over the floor. They claimed to have found them all but later
on I discovered that the thrust washer was not in the bag of bits. With the de-compressor
parts removed, they were able to grind the cam and Parkerize it afterwards.
When I took it back to my local machinist friend’s shop we discovered the
missing thrust washer. I ordered a new one from Honda, but the only ones were
in warehouses back East and it took a week to get one out to SoCal. In the
meantime I found that the oil filter washer from a CB750 was about the right
size, so I used that when the parts were pressed back onto the end of the
I thought I was
near completion when I discovered that the funky cylinder head-mounted camchain
tensioner requires a Honda special tool in order to retract the tension from
the camchain guides. The tools are available for about $50, so I ordered one of
those, too. In the meantime I tried to wrestle the engine back into the chassis
by myself and fought it for more than an hour before it finally found just the
right positioning to get the mounting bolts installed. The only other GB500
engine install I have done was when I lived in Hawaii and that time I wound up
laying the engine on the floor and dropping the frame over the engine so I
could get the alignment done. It is a total PIA and the frame tubes are all
scratched up from the wrestling match efforts. Apart from flywheel pullers, I have never had
to use a special tool to reassemble a Honda engine until this one. Nevermore!
From the time
the bike was picked up, it has been almost exactly 2 months of work and waiting
to get the GB500 back up and running again. After several weeks of waiting the
camshaft was ground, but the result was that the de-compressor gear really
didn’t want to work with the re-profiled cam lobes, so the whole assembly was
removed from the camshaft. Apparently only the US versions of these bikes had
one in the first place, so no big deal to remove the de-compressor parts.
Just as I
thought the end was in sight, the first firing of the engine revealed a pair of
exhaust leaks. I had ordered the wrong head gasket (XR500, instead of the one
for the GB500) and it didn’t have the extended sections to encompass the PAIR
(pulse air) system transfer ports! It took another three hours to R&R the
cylinder head gasket to repair the exhaust leak problem. Once that was finally
accomplished, the bike fired up once again and seemed to be running well.
road tests failed to reveal any major further issues, so the bike was taken out
on our Sunday morning rides up into the mountains and back, about a 65 mile
round trip. With scuffed in new BT45 tires, new front brake system overhaul and
new pads, everything is getting a new break-in period, but so far it seems to
have been a success in the end… but what a lot of work and expense!