I haven’t been very consistent in my blog postings lately,
due to a number of situations that have arose over the past month…. But I’m
BACK now.
Let’s see… There was the matter of the CL125A, which needed
some attention for oil leaks, fresh rubber and some performance/appearance
issues. The shift shaft seal was replaced, new fork boots and one fork seal
were replaced, new tires/tubes installed and the muffler was welded up on the
inside where a hole was rubbed through from contact with the shock absorber. A
new battery was procured, of course, and the fuel system cleaned and re-jetted
for modern fuels. It was too underpowered to make the hill nearby which leads
to the post office, so the bike was offered up for sale and found a new home in
Ventura, CA as a result of an eBay auction. The buyer had one just like it when
he was a kid! That will sell a bike every time, when you find that right buyer.
Busy, busy
While that one was pending sale, a 1982 Honda FT500 Ascot
showed up in running condition, but needing some TLC in the usual places that
these bikes require. The air box was cut in half, which allows a large K&N
air filter to be used in conjunction with some adapters to allow use of the
crankcase breather system. The bike has a custom-made rear luggage rack that
even included little LEDs in the back end of the rack rails. The owner worked
at a metal fabrication shop and thoughtfully created a sturdy rack for his
lunch box, while commuting to work. The seat cover was original and splitting
apart, so a nice aftermarket replacement cover was procured and installed with
the help of an upholstery shop. My staple gun didn’t have enough power to put
staples into a plastic seat base. Fortunately, the seat foam was still intact,
so a cover was all it needed to make it attractive again.
After some trial runs, it seemed that the carb jetting was a
little off. The spark plug looked pretty good, but there was a flat-spot off
the bottom into mid-range that was annoying. All the testing revealed an oil
leak at the camshaft rocker arm cover, which was an ongoing problem with those
bikes and the related XL500s back then. I ordered a gasket kit (EMGO) but the
head gasket was less than stellar. A couple of the bolt holes were off by half
a hole. That necessitated some gasket mods to get it to go together again. The
camshaft lobes were somewhat pitted, but not necessarily from lack of
lubrication. This seems to be another problem area for these bikes, perhaps due
to insufficient surface hardening. When the rocker cover was removed, it was
evident that someone had been in there before, as a number of bolt holes had
inserts installed to repair stripped out threads. Again, this is another
long-standing problem with these bikes.
The balancer shaft adjustment can only be made by removing
the clutch cover. The spring-loaded tensioner arm moved a couple of notches
before coming to a stop. Honda recommends backing off the tensioner one notch
from where it stops.
When the carburetor was removed for inspection and jetting,
it appeared that the slide piston was somehow jamming up into the top cover, so
the throttle never really fully opened to full power. A friend had some
CX500-650 used carburetors, which share the same components as the FT500s, so
that fixed that problem. Eventually, I would up with a #150 main jet, the CX500
needle with shims and a larger idle jet to finally solve the performance
issues.
The bike came with bar-end mirrors, so I wound up spending
over $100 for a set of OEM mirrors, which are just about gone from anyone’s
stock now. After a test ride, the right front turn signal lens promptly broke
off and fell into the street as I came up the driveway. A pair of OEM lenses
was found on eBay for $15 including shipping, so now I have a spare, just in
case this happens again. I have never seen that happen before! It was like
something out of a comedy show… ride, ride, clink, clink…. Stop and recover the
lens from the driveway. All the other three seem to be just fine.
The electric starter systems on these bikes are somewhat
problematical so the covers were removed and the system inspected, cleaned and
serviced. So far, it is working well now. The FT500 is up for sale now, as I
continue to try to trim down the motorcycle herd nestled in the driveway.
Funny/sad
The last three people who reported hard starting problems
had bikes with battery levels that were WAY TOO LOW to allow the battery to
charge up and stay charged. These lead-acid batteries need regular checking at
least once a month.
Sad/scary
Finally, a long-time customer rang me up to ask about
redoing the top end on his CT90K1 Trail 90. In general, parts have been
available from Honda and the aftermarket for many years. Honda must have build a
couple of million of the OHC 90-110cc horizontal singles since their 1965
introduction. Honda placed those engines into ST90, S90, SL90, CT90, ATC90s and
many, many more.
Taking the top end off is about 15 minutes work, even with
hand tools, so the autopsy can be done quickly when there are problems. The
bike was using smoking and using oil since the last visit, so the focus went to
the piston/rings/cylinder bore primarily. Despite a smooth-looking bore, when
the top compression ring was removed and fitted to the ends of the bore, the
bottom measured out at .008” while the top measurement was out about .020”+, so
obviously there was a taper in the cylinder bore.
The bike only showed about 4400 miles on the odometer, but
the overall condition was fair-average. The bike has been used as designed, out
in the sand, gravel and general off-road conditions. When the piston was
extracted, the first thing noticed was a loose-fitting piston pin clip,
consistent with those found in a lot of Chinese-made piston kits. The piston
was marked 028 (product code for an S90), but it had a 3 piece oil-ring, which
the bike never came with from the factory. I wondered why a low-miles bike
would have a replacement piston until I removed the carburetor and discovered
that the little choke flap was missing from the choke plate! It was another
case of flap failure, which I have seen on many of these kinds of carburetors
made in the 1960-70s. The spring loaded flap fails and gets sucked into the
engine, where it usually jams the intake valve open long enough to have the
piston come up and bend it smartly. The valves in the head were cupped at the
seats, so new valves were ordered and fresh valve seats cut in and the head
assembled for final work.
There wasn’t any sign of catastrophes inside the combustion
chamber, but the head could have been changed when the piston was damaged along
with the valve. There were a few Heli-coils in the threaded holes, so obviously
someone had been inside the engine at least once before it came my way. When I
started looking for an over-sized piston, I discovered that Honda has
discontinued the S90 series pistons and ring sets from US inventories! It is
one of those things that will last forever, but I see that this isn’t the case
now in the 21st century. I was able to find one set of OEM rings at
a Honda dealer up in Orange County, plus one matching OEM piston from an eBay
seller in Texas. I tracked down a pair of 14mm wrist pin clips after going to
two different dealerships….. ?!?!? It really is shocking that you cannot find
wrist pin clips in stock at a motorcycle dealership these days. The first local
dealer didn’t stock them and the second one, some 12 miles away only had two available.
I guess people are not rebuilding their bikes much anymore…. Sad isn’t it?
I did find that the camchain was pretty well stretched, so a
new chain and guide roller were ordered up, along with a quality Vesrah-branded
gasket set. These engines have a valve stem seal on the exhaust valve side,
which was replaced with a spare that was in stock, but it was surprising that
the complete gasket set didn’t have this tiny part included.
Two 25-mile round trips later to drop-off and pick-up the
newly bored cylinder yielded a nice smooth, straight and round cylinder to fit
a new piston into, now at factory specs. As fast as it is to tear down one of
these engines, the reassembly/repairs take several hours. The valve job
probably took about 45 minutes as the seat contacts were adjusted several times
until they centered on the valve head. Scraping gaskets, checking threaded
holes, replacing seals, doing a valve job, cleaning parts and carefully
reassembling this little engine takes a lot of patience and some expertise.
With the carburetor cleaned out, float adjusted and some new
gaskets/seals installed the engine finally was ready to run, once again. The
engine fired up after a few kicks and once the oil solids coating the inside of
the exhaust system burned off, the engines ran smoothly, with little noise or
smoke evident now. It will probably receive a slow break-in period at the hands
of the owner who has enjoyed it, even as it was, for many years.
The CT90s have a dual activated rear brake, which also
incorporates the brake light switch. If either of the rear brake functions jams
up, the brake light will stay ON and eventually run the battery down because
the little 6v system is barely up to the task of keeping a fully-charged battery
up to normal voltage levels. This bike was a 1969 CT90K1 which had a front
brake light switch function as part of the brake cable. The cable was changed
to a non-switch version, so loose wires are flying in the wind at the front
fork area. Honda made many changes to these bikes through the years, so keeping
them stock with OEM parts is a challenge now.
I think that brings us up to date so far… MrHonda
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