Well, another refugee from Craigslist has found a temporary home in the workshop at Casa de Honda!
So, just WHAT is a CBX? Released in late 1978 elsewhere, the big 24 valve, six cylinder, five-speed bike weighed into the heavyweight bike arena, in the US, as a 1979 model, sporting 105 horsepower and hauling a six-hundred pound chassis. Honda’s bid to keep the weight down to something reasonable led to some questionable choices concerning fork diameter sizes, use of single-piston brakes and a somewhat spindly rear swing arm pivot bolt. Honda addressed some of the concerns with wider rims, larger swing arm pivot bolt on needle bearings, instead of bushings for the 1980 editions. It wasn’t until the bike morphed into a “Sports-Tourer” in 1981-82, that twin-piston brakes, larger forks, a single-shock Pro-Link swing arm and vented brake rotors were introduced. By that time, the market had moved onto more powerful and less complicated designs, so there were many leftover CBX bikes in warehouses which were eventually donated to colleges, prison systems and other educational venues.
I have owned about a half dozen of these monsters, since 1980 and this one is probably not the best one I have had to date. Basically a CBX “Kit” in that the motor was on a dolly and the other parts were in little zip-lock baggies (other than the seat, fender, exhaust and gas tank). The speedometer shows about 26k miles and overall it seems like it hasn’t been crashed or seriously damaged in the past. The seller claims to have ridden it back to his warehouse in 2007, took the bike apart to do a “restoration” and once the chassis was freshened up, the progress ground to a halt.
The posting was in the middle of the week, so fewer folks were able to come for a look, apparently. The seller was super nice and when we struck a deal, he offered to load it all up and bring it to my house, which is about 10 miles away. What could be better than that?
First order of business, after doing a rough inventory, was to extract a broken bolt, lodged in a forward engine mount plate. After about 20 minutes of drilling and messing with it, I was able to extract the bolt end and clean up the threads successfully. One step forward…
The seller said he drained the fuel and oil from the bike during teardown, so that the old gas wouldn’t congeal inside the float bowls. When I started pulling the carb rack apart, I discovered pockets of rust particles lodged in ridges along the float bowl edges. The air cut valve diaphragm had a small tear, rendering it useless and causing a vacuum leak in the end carburetor. I cleaned as much as I could by hand and hauled the whole stripped-down rack to my friend Scott’s house to try to get it cleaned up in his ultrasonic cleaner. Unfortunately, we discovered that the carb rack, which is the size of a large loaf of Italian Bread wouldn’t fit more than the two end carburetor bodies in his cleaner tank! We did both ends, which was very helpful and I wrapped them back up, strapped them back on the rear of my newly-acquired W650 Kawasaki and returned them to the shop for more cleaning and reassembly.
A couple of years back I purchased a large K&L Keihin carburetor service kit for $100, containing lots of o-rings and some of the little rubber plugs for the idle jet circuits. Honda’s carburetor packing kits run about $30-40 each, which times SIX equals a lot of cash. Other than lacking float bowl gaskets, the service kit will fix me up just fine. I am not going to tear down the whole rack to service the o-rings on the fuel and air connection tubes, unless something reveals itself during startup. This is a roll of the dice, as carburetor service requires dropping the motor down in the frame, to allow the carburetor assembly to be removed.
Switching from area to area on the reassembly, I removed the alternator from the side of the motor and took it apart for inspection and cleaning. There was more than a little oil buildup inside and one of the two carbon brushes looked to be too short to make contact with the rotor’s slip ring tracks. Honda’s price on one of the two required brushes is nearly $25, so I turned to eBay for alternatives and found a pair from Rick’s Electrosport for $20 delivered. A new seal behind the rotor housing bearing should keep the crankcase fumes and oil out of the electrical works once it is replaced.
The electrical systems in the 750-900-1000-1100 Fours and the CBX sixes are nearly identical and all suffered from various ailments, including defective rotors, overheated electrical connectors, failed rectifiers/regulators and spark units that go awry. The wiring harness had a couple of melted wiring connectors and a fuse holder that disintegrated. Until everything is repaired and tested, it is hard to say what is going to work and what is going to be a problem. It is hard to understand how the previous owner was able to drive this bike home, given the contaminated carburetors and the probably inoperative charging system. CBXs and the related fours all featured a halogen headlight that draws a lot of current; so much that the bikes can’t keep up with the current draw at idle and slightly above. Doing an “upgrade” to a larger headlight bulb tends to take the whole system down in a hurry. CBX owners discovered that removal of the “spacer” next to the standard battery allows for installation of a Gold Wing battery with more juice reserves.
With the motor out of the chassis, I will probably venture into the top end enough to check the valve clearances and camchain tensioners. The clearance check can be done in the frame, but sneaking the valve cover off and on without snagging the cover packing can be tricky. With a little cleaning and paint, the powerplant will be heading back to the frame in the next week or so.
Stay tuned for the next episode of “As the engine turns.”
Bill “MrHonda” SilverHonda’s Sexy Six… the CBX
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