Thursday, March 14, 2019

1959-64 Honda CB92 Benly 125 Super Sport


Of all the bikes that American Honda has brought into the U.S., the little CB92 is the most enigmatic and lately the most expensive and sought-after of any small-bore twin ever sold here. According to AHMC, there were only about 1,000 models brought into America, covering the 1960-62 year range.
Most Honda enthusiasts have never heard of a CB92 due to their scarcity and the fact that they were never really a practical model for sale here in the US, especially from a previously-unknown manufacturer who had only arrived in Los Angeles in June of 1959. So, for those of you who have never heard of the little Benly 125 Super Sport, here’s a bit of history for you.

If you have read my previous posting, you will note that the 1960s Benly twins were offered in a couple of different models, varying from Sport to basic transportation configurations.  The very name, “Benly” is a rework of the Japanese word “Benri,” which means convenient in that language. Soichiro Honda sought to bring quality, reliable and functional motorcycles to the world, starting back more than 70 years now and this was one of the tools he used for customer satisfaction.
Mr. Honda had traveled to Europe to see the Isle of Man races, all the way back in the early 1950s and vowed to bring his own racing machines to the event, sometime in the future. While in Europe, he studied what was being offered for sale there and brought home various motorcycle components in his luggage in order to further study what was working for those manufacturers and how those component ideas could be incorporated into his product line.

Japan had a history of importing various motorcycles from the UK and Europe to help shore up their own fledgling motorcycle market. In many cases, these bikes were reverse-engineered in Japan and offered as unique, homeland models. When you study the NSU Fox, you will see a lot of similar design features in the first Honda J-Benly machines, starting in 1954. But Honda didn’t copy the engine design and created their own 4 stroke, pushrod version for the similar-looking NSU Fox pressed steel frame and chassis.  The little J-series Benly singles ran until 1958; then all new machines were close to their release dates. First, the dry-sump OHC Dreams arrived in late 1957 and continued on until the wet-sump models replaced them in 1960. Next the new OHC 125 Benly twins appeared in 1958, initially as a C90 model, without electric starting, then in 1959 as the C92 with electric starter motors attached.

While the C92 was created to be “convenient,” Honda released the CB92 (and a 150cc CB95) in 1959 to take on the 125cc Sport machines of the day. TSB material, distributed to Honda dealers, illustrated the many changes to the basic designs, as HMC sought to solve the problems of running small bore engines at an unheard of 10,000rpms, as street bikes or race bikes.
Honda’s basic architecture for the CB92/95 was a pressed-steel chassis with dual rear shocks and a leading-link front suspension supported by two more shocks. The magnesium 200mm brakes were DLS on the front and SLS on the rear. Both the brake hubs and the backing plates for the brake shoes were made from cast magnesium for the first 3 years.  Clearly, this was more than sufficient braking for a 250 lb. 125cc street bike, as the same-sized brakes were also used on the 250-305 CB72-77 Super Hawks which weighed around 350 lbs. The magnesium brake parts tended to become brittle, cracking around the spoke holes. They were easily damaged by water, as well, so Honda switched to aluminum castings in 1962.

The fuel tanks came in various designs, too. Early ones (1959) had decals on the sides, replaced by the more typically seen small, round plastic tank emblems scripted with either BENLY (1960) or Benly 125 (1961-later) thereafter. The early 1959-60 fuel tanks were alloy and came with an internal vent system. This was replaced by a vented fuel cap style, both types of which screwed onto the tank opening. After that, Honda made the fuel tanks in steel, first with a screw-on cap, then with the more typical ¼ turn twist cap used on many other models of the era.  Three different sets of knee pads were fitted through the years, with some glued onto the tank and others clipped onto brackets welded on the tank surface.

Five different tail lights were used through the production years. The first ones (250 code) were small rectangles with the bottom dropping down to illuminate the license plate. Then, came either the rounded shaped small tail lights with 253 codes or the straight-sided rectangle shaped 255 code lights. In 1962 Honda began to use the 268 (CB72) generic tail light assemblies used on many other models, however the 1962 lenses were shorter (at least in the US) than the later 1963-on extended ones.

All the various light assemblies used different bulb bases, as well. The small rectangular lights had a tiny double-ended bulb with long, fragile filaments. The high-frequency vibrations of the engine transmitted a buzzing feel to the rider and attached components, including the tail light bulbs. These early lights gave off very little light, anyway, as the electrical system ran on only 6 volts. The 268 lights were larger and had a bigger reflector and bulb head to increase night-time visibility.
In the US, almost all motorcycles required a sealed beam headlight bulb, but there were domestic and Euro-UK versions using replaceable bulb elements. US models were never required to have “winker” (turn signal) lights, but there were requirements for Germany and Scandinavian countries. Obviously, the wiring harnesses, handlebar switches and various turn signal mounts were required to complete the additional lighting requirements.

Early model machines had a 3 bolt handlebar mount system which proved unstable so a 4 bolt mounting was designed and implemented. 1959-60 models had smaller diameter brake and clutch cables, which were upgraded along with the star-shaped cable adjusters. Early speedometers came from Yazaki and had no high beam indicators installed in the face. Nippon Seiki took over the meter building and later meters had an integrated high beam indicator light installed.  In the US, the high beam indicators were required from 1964-onwards, however no CB92s were sold after 1962 in America, but the CA95 Benly 150s continued on until 1964.

First-generation cafĂ©-racer handlebars called “Ace” bars were replaced by the flat handlebars from the CB72.  Early bikes came with alloy side panels and rear shock trim pieces, replaced with steel units around 1962. The first generation front fenders were also from alloy and also replaced with steel units in later years. The first issued bikes came with a large cast alloy rear brake stay, which was replaced with a thinner, stronger steel unit, so the swing arms were changed to reflect this switch, as well.

While the CB92 engines seem to be identical to the 150cc C/CA95 at first glance, the profile of the fin pattern on the cylinder head and cylinder block were different. Viewed from the side, the fin pattern on the 125s is a nice smooth curve, whereas the 150cc head and barrel showed jagged extended fins that interrupt the profile shape. 1959 and early 1960 bikes had no provision for a tachometer drive. Honda engineered a whole “YB92” racing kit for road racing which included a tachometer which fit into the headlight shell, in place of the speedometer. The cylinder head cover was modified for the tach drive components, as was the side of the cylinder head where fins were cut away to give clearance for the tach drive and cable. Obviously the camshaft end was extended to allow the cam to engage with the tach drive unit. 

The early engine cases had a “rear breather” installed at the rear of the top engine case, which separated the oil solids from the vapors.  The transmission gears seemed to throw a lot of oil backwards into the breather system, so the breathing duties were moved up to the top cylinder head cover, fitted with a breather plate to do the same function. To match the various crankshaft configurations, the engine cases were modified to suit. The outer clutch cover and dyno covers are narrower on the CB92s, as both the shift shafts and kickstarter shafts are shorter to help narrow the overall width of the engine.

The first year’s cast iron cylinders (replaced with sleeved alloy cylinders in 1963) had a machined slot cut in the base for an oil feed channel which lead all the way to the left side cylinder where a window was cut into the back of the cylinder to help lubricate the left piston.  Apparently, the early oil pumps and crankshaft designs failed to properly lubricate the left side of the engine and left side piston and big end failures were not uncommon. There are three different crankshaft configurations for the various years of production. The 1959-60 crankshafts had three half-ring retainers to keep the main bearings located in the cases.  The center main bearing was larger than the end bearings by 1mm. The 1961 engines used a pinned center main bearing, which was the same size as the end bearings which were still held with ring retainers.

By 1962 all three main bearings were pinned to the cases to prevent the main bearings from turning at high rpms.  The early oil pumps had a round screened inlet. This was replaced with a larger, square shaped pump inlet and different pump plunger. The oil filters, which connected to the end of the crankshaft, came in different lengths, too, so care must be taken to choose the correct replacement parts during an engine overhaul. Early outer filter covers were blank, followed by ones with HONDA stamped onto the faces.

Honda used a stainless steel faced exhaust valve on the CB92s, not seen on the other Benly models. The early bikes had alloy valve retainers, which were sourced from the early generation C110 Honda Sport Cubs. The valve springs were of a higher quality to resist valve float at high rpms.
First generation CB92s had just a small 18mm carburetor, which restricted speed and power. Honda upgraded the carburetors with a 20mm version used on the CA95 Benly 150 Touring machines.  Obviously, use of a single carburetor to feed a high-spinning twin cylinder engine was somewhat counter-productive, but there wasn’t sufficient space to stack a pair of carburetors behind the cylinder head with allowances to attach air filter tubes and to clear the edges of the pressed steel frame.  Some enterprising racers have welded and reworked the heads for dual carburetors, as well as the installation of a CB125K3 5 speed transmission, which can be fitted with minimal modifications.  With intelligent modifications, these bikes are capable of 90+ mph. Given the lack of proper shock damping in the suspensions, racing these bikes at those speeds would be quite exciting to say the least.

Exhaust noises were suppressed by large seamless mufflers in the beginning.  By 1963 the replacement mufflers were made in two halves and welded down the vertical seams. While the early mufflers had a clamp-on connection to the headers, the later ones had silicone o-rings fitted into muffler inlets which had welded-on o-ring retainers installed.

The 3/4th length CB92 seats were designed for just a solo rider, however Honda did offer some clamp-on rear passenger pegs, which were fitted to the swing arm.  Still the seat was not elongated for dual seating, so a small passenger would have been ideal to suit the narrow confines of the rider and passenger seat space availability. For racing a shorter race kit seat was part of the YB race kit, which provided a kickup at the back to help keep the rider from slipping off during competition.
The actual YB92 race kit was quite extensive, offering open megaphone exhaust pipes, a racing camshaft, electric starter elimination kit, the race seat, a very stripped down wiring harness, alloy rims, front brake plate ventilation plate, lever brackets with no mirror holes, a high performance racing coil, the aforementioned tachometer, high compression pistons (like the street pistons, they are left and right side specific). Additionally, Honda provided a set of “Scrambler” exhaust pipes and handlebars for dirt competition, but the kit was primarily setup for road racing.

This presentation is just a broad overview of the minutiae involved in restoring these 60+ year old machines.  Just finding one that has all the original parts will generally set you back about $5k if you can find one at all. Running, intact machines easily sell for $7k on up and fully restored bikes can shoot up to $15-20k (asking price) for perfect examples. Always confirm that the engine and frame numbers are within a couple hundred digits of each other, generally less than 100 in most cases. Look for cracked hubs on the magnesium equipped models and CA95 top end switches, which were common back in the 1960s. Very few actual CB95s have been verified anywhere in the world, but at least one has been noted in the US.  Dave Ekins, noted Honda rider/racer, raced one in Scrambles and TT races, winning several races, but it was eventually banned as it was not an actual US market model.

According to Honda’s sales records in the US, all the 1962 bikes were supposedly race models. Still a bone of contention, Honda showed factory-fitted CB92R models in their advertising, but next to none have ever been verified as actual factory CB92R machines. There are no special serial numbers for the race bikes and many were modified at dealerships. Your author owned a 1961 CB92 that came with an AHMC MSO that stated it to be sold as a CB92R model, but no traces of racing parts were seen on the bike. The bill of sale from the dealer to the first owner stated that a set of mufflers were included with the purchase, however!



Your author has owned several CB92s, including#24 from the 1960 production which was sold new in San Diego in 1960. Overall, the riding experience is somewhat underwhelming due to the high-strung engine characteristics, grabby brakes and under-damped suspension system components. These days, they have become “garage art” instead of daily drivers or even weekend exhibition mounts. Replacement parts sources are all dried up for the most part, so joining a CB92 specific forum is a must, if you are scouting for a bike or just a few NLA unobtainium parts.  These days, it takes a village to raise a CB92 from the dead. Patience, a generously outfitted wallet and careful attention to detail will eventually pay off, if you REALLY want to own a CB92 125 Benly Super Sport.

Bill “MrHonda” Silver

3 comments:

  1. I was an owner of a cb92 as my "step up" model from my ca100. Dumbest thing I ever did was trade it in on a CL72. Wish I had one today.

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