Thursday, May 9, 2019

Age before beauty, when vintage bike shopping…

It’s hard to resist that perfect dream bike, when it suddenly comes up for sale, especially when it is described as one-owner, like-new, all stock and original, etc. When properly stored, you can often bring those sleeping beauties back to life with just a new battery, fresh fuel and spark plugs. Most of the time, however, the actual story is that they were left with old fuel, old oil and uncovered in the back of some garage, shed or storage building by an owner whose life was overtaken by events.

Recently, an unmolested, 600 original-mile 1988 Honda Hawk GT650 popped up on Craigslist, by the first owner who bought it as a Christmas present to himself. He rode it 600 miles and then parked it deep into the back of his garage. The last license tags were from 1994 and apart from a change in the hand grips, the bike was absolutely original and stock.  It was buried so far deep in the garage that apparently light and ozone aging wasn’t a big issue both of which can cause significant deterioration of the cosmetics and any exposed rubber components.  When the bike was pushed back out to the front of the garage for sale it gleamed like it was just a few years old, not thirty years old.

It was one of those bikes that you just can’t let pass by, but there were dark secrets, yet to be discovered, after a successful purchase and delivery back home at Casa de Honda. In this case, the bike sat for years with perhaps less than a half tank of gasoline remaining. The years of heat and cold cycles inside the garage caused the airspace inside the fuel tank to condense moisture out of the air resulting in rust and varnish build-up inside the tank. At some point in time, a misguided attempt to revive the bike occurred and a can of Kreem fuel tank sealer was poured into the fuel tank, right over the rust and varnish. The congealed mess was the first thing noticed when the fuel tank cap was opened up for the first time in 25 years. Eventually the tank was rescued after a combination of degreaser, phosphoric acid, Metal Rescue and MEK were used to dissolve the rust, melt away the varnish and loosen the Kreem coating, which was locked into the many nooks and crannies inside a CA spec fuel tank. Eventually, it was clean enough to use once a $60 kit of Caswell fuel tank sealer was installed into the newly cleaned tank internals.

Of course, the rest of the fuel system required cleansing and a few new parts. It is easy to overlook some crucial components and systems when you are star-struck by the overall appearance of a lightly-used machine that is 30+ years old. There are many small details, easily overlooked or disregarded, that can trip up the maiden voyage of a newly revived classic bike.

How about a Honda Four?
Honda’s four-cylinder street bikes have been on the scene since 1969 and come in an array of shapes and sizes through the ensuing years. Rehabbing these machines takes extra care and effort in order to regain their former glory, especially from a mechanical aspect. Honda built thousands of 350, 400, 500, 550, 650 and 750 OHC powered machines for a ten year run and plenty are left to discover and revive in the 21st century. A recent “internet find” in the form of a 1975 CB400F, which was showing 6100 original miles, is a good case in point.

This particular bike was offered as a “runner” with original miles.  It had been stored for some 40 years by the original owner, then quickly revived and ridden sparingly in the past year by the current owner. There is a whole blog page about this particular machine, which had been clothed with rare (1 of 3, according to the story) Tracy one-piece bodywork. The bike was purchased without the benefit of an actual live inspection and detailed photos, which might have given a better indication of the actual condition of the bike. All indications are that the miles are probably genuine, however numerous modifications involving the bodywork installation and other “mods” left the little machine suffering in many areas of its various systems functions.

For some reason, virtually every used Honda CB400F that has come my way has needed fork seals, tires, brake caliper/master cylinder overhauls and carburetor overhauls, whether it was running or not. This bike was not an exception to the rule…

First, the battery wasn’t sufficiently charged enough to start the engine, when the bike was delivered from 750 miles away. There was little fuel left in the tank because the bottom of the fiberglass was leaking gasoline right through the original fuel liner and bodywork layers. An overnight charge of the battery brought it back up to function allowing the engine to spin over heartily. The carburetors were removed for cleaning and inspection. Running off of an auxiliary fuel tank, the engine fired up on the freshened up carburetors, which were mounted on new intake manifolds. The bike sounded somewhat rough at idle and seemed a bit erratic in low speed running conditions. New spark plugs were installed and spark plug caps checked for resistance values. Three of the four caps were up at around 9-10k ohms and the last was about 6k. Standard resistor caps are 5k ohms, so there was definitely excess secondary resistance in the coil outputs. The coil wire ends were trimmed back slightly to uncover fresh wire strands when the caps were installed. The spark timing was checked and adjusted to prevent over-advancing spark timing. Aging spark plug caps have become a major issue in reviving these vintage fours in of all sizes offered from the 1970s.

When the carburetors were disassembled and cleaned, new o-rings were installed on the fuel delivery tubes, which are interconnected between the bodies. Disconnecting the carb bodies in order to change the o-rings requires attention to the interconnecting linkages and how they come apart and go back together again. There is a lot of extra effort involved in cleaning and resealing the connection tubes, but it is a vital step in a successful carburetor cleaning phase. It is easy to assume that the tube o-rings are still okay, but when old fuel is left in the carburetors, the leftover fuel residues will easily be flushed into the float valves, causing flooding issues later on. Going to the work in removing and cleaning the carburetors is something that you don’t want to repeat again, especially with certain models.

When the 400F was fired back up, the #4 cylinder pipe was cold, even after a few minutes of run time. Sure enough, a bit of debris had worked its way into the #4 carburetor idle jet and blocked the passage of fuel fed to the idle circuit. Carburetors on the 350-400F are relatively easy to R&R, so it doesn’t take a long time to pull the rack and recheck the jets and float levels, but the carburetors on the CB500-550s are quite challenging to remove with the close-fitting air box in the way. So, take your time and be as clean as you possibly can be with carburetor work. Fortunately, the engine went back on-song again, once the pilot jet was cleaned and the engine really began to sound like the low-miles unit that was indicated on the speedometer.

Long-term storage usually causes issues with the ignition points, as well. Generally, one set of points is usually open on a four cylinder machine and corrosion can form on the open point faces, causing high resistance when trying to trigger the ignition coil primary windings. The problem with points is that the rubbing blocks wear down, causing a decrease in the point gap. This leads to late spark timing and sluggish running problems. Point face corrosion can prevent the transfer of power through the points in extreme cases, so that the coils never fire at all. A small point file or some emery cloth will burnish the contact faces to allow a nice clean metal-to-metal contact which is what the ignition coils really appreciate. The points are basically just an adjustable “on-off” switch for the ignition coils. The point gap needs to be around .012-.016” wide, then move the base plate until they just open at the F mark alignment on the crankshaft flywheel or spark advancer markings.  Another feature to check is the spar advancer unit for full function. The point cam can get gummy or even seize up, preventing spark advance or causing a slow idle-down condition. Most of the 1960-70s machines, which were equipped with points and condensers, can be retrofitted with efficient and trouble-free electronic ignition systems, which require nearly zero maintenance.

It’s a magical moment when you discover that wonderful rare bike find, still in near-new and original condition, but take a moment to consider the amount of time, money and work that will probably required in order to make the inner beauty match the outer beauty. If you have the ability to do the bulk of the work yourself, the end result will be gratifying and you will save a lot of money in repair work. If you are not so mechanically adept, be prepared to pay for technical services to be rendered, often in ways that are not apparent on the surface.  Hopefully, you have done your studies on a particular model and have prepared yourself with tech data and resources for parts and services.

Motorcycles are complex machines with numerous interconnecting systems, all of which must be working at normal specifications in order to have a safe and enjoyable riding experience, well into the future. Don’t let the beauty overwhelm your common sense about what lies ahead in the forms of repairs, restoration and general maintenance of your dream machine. The little CB400F reminded me about this lesson, especially when buying over the internet.

Bill “MrHonda” Silver

1 comment:

  1. Thanks for the realistic aspects of buying non-running vintage motorcycles. The fuel tank interior is an often overlooked source of many problems.