Tearing down the engine to install the crankshaft gave a chance to look at all of the parts that I had lovingly fitted together the first time. All of the parts were looking pretty good, but the camshaft was working loose in the minuscule cam bearings of the early 1-piece head design. I consulted with my cam-grinding friend and we decided to have the cam journals turned down, hard chromed and finished back to size again. I was assuming that the wear was more on the camshaft than in the cylinder head. For the most part, this modification worked well, but an installation of needle bearings on both ends of the cam would have been even better. Wobbling camshafts cause erratic ignition timing because the point cam is on the end of the camshaft. Any play will change the point gap, which changes the ignition timing. I just had to keep an eye on the wear and tear during and after the races to see if the problem would worsen or not. Ultimately, I was able to race the whole season with that combination without failure.
I was so buoyed up after the first AFM race, that I joined the CMC (formerly the ACA) and thus had two or more chances to race each month. Other than a disastrous piston seizure at Orange County, when I forgot to re-jet the carb after I removed the air filter (I was riding the bike on the street between races!) the little orange bomb just ran and ran…. and won and won again! When the two Yamaha brothers showed up, running their 100cc bikes in the 125cc class, I showed them the door rather convincingly. One decided to join me in the ranks of the 4 strokes, and bought his own CB 125 Honda. He decided to have noted engine specialist Jerry Branch port the cylinder head to get an edge on me, but the valve springs collapsed through the enlarged intake port and he was back to square one again. Despite my home-built engine (I ported the cylinder head myself), he was never able to head me at any of the tracks.
All kinds of bikes made appearances during the year. I recall someone showing up on a Suzuki 125 Stinger, a Bultaco Streaker (very trick bike!), Sears 125 street bikes and one particular guy who kept showing up with a flyweight Kawasaki 90, that was getting faster every race. He always had problems when he got into each race, however… he generally crashed on the first lap. Either his over-enthusiasm and/or lack of brakes on the tiny converted, enduro machine caused him to crash on the first or second lap. I always figured that if we were ever to stay on the bike, I would probably be in trouble by the end of the race. He never did defeat me, but came close at the last race of the season, back at Riverside Raceway. Even in practice, I noted that he would pull slightly away from me on the back straight, as both of us exceeded 80 mph. By the middle of the race, we were passing and 15 re-passing each other, repeatedly, as my bike would out-brake him and out accelerate his peaky two-stroke in the slow corners, only to have him run me down on the straightaway. The harder he pushed the little Kawi, the more it developed a “speed wobble” going through Turn 9, at full throttle. I tucked in behind him, coming out of the turn, watching the machine shake its head more and more. Finally, I cut the corner sharper than usual to get out of his draft and watched him as he wrestled the bike at speed.
Just as I was moving past him, headed for the White Flag, I caught a wild motion in the corner of my eye and took a quick peek. Rather than back off, to settle the bike down, he persisted in trying to keep ahead and finally the machine had decided that that was enough and pitched him off at 80+mph. I finished my last lap in 1st again, which clinched my 125cc Production championship and watched nervously as the rescue crew attended to the fallen rider and machine. After the race, I went to check on him and assisted his father in getting the battered Kawasaki into his truck. I heard, a week later, that the rider had suffered multiple fractures of one ankle. It took over a year to rehabilitate his injured foot and leg. A couple of years later, I received a wedding invitation from him and I decided showed up to relive the moment again as well as to bid him a happy married life. He never raced again, after the crash, but did build and maintain a race bike for a friend. I had not had any crashes for the entire season, luckily, but my turn was coming up a few years later.
Honda CB125 Production Racer in a nutshell:
Starting with a brand new, stock machine, I replaced the rear 17” rim with an 18” hoop and installed a set of Yokohama Road race tires in the 2.50x18” sizes. I added a set of S&W shocks on the back and replaced the handlebars with some clubman bars, routing the excess front brake cable so it continued to function correctly. Off came the turn signals, passenger pegs, side stand, centerstand and any other excess chassis items, not related to racing. In its final form, the engine had these modifications: CB100 head (no chamfer on the combustion chamber = higher compression) lightened valves, S& W valve springs, Yoshimura Road Race camshaft, point cam, slipper skirt piston (The XL125 had a similar piston crown configuration), lightened crankshaft (MUCH smoother at 11k rpm!). Cranking compression was 225 psi! I found that the carburetor from the XL125 was 24mm vs the stock 22mm mixer, so installed one, with some improvement in top speeds. I discovered that there were different transmission ratios for the various CB/CL/SL100-125 versions, so installed 2nd and 3rd gear sets from a CL100, I think. I used the stock ignition coil and points, but added an additional spring leaf to increase the pressure on the points at high speed. On some occasions, I removed the rotor after I had checked the ignition timing prior to the race.
The muffler was stock in the beginning. I ground off the edge welds once and split the muffler open, removing the baffles and added some length to the exhaust pipe, but the weld broke the first time we raced it, after we had welded it back up and re-chromed it again. I had to grind it apart again and remove the loose pipe extension. We just welded it back up, almost empty inside. I added a little accessory fiberglass racing seat to save some weight and lower my riding position. CB125s came with solid foot pegs, so we cut them off and welded on some fold-up pegs, in the same location. The rules at that time for Production Racing were that it had to have a stock frame, gas tank, muffler, front forks and that the engine must use parts that were offered in that series of machines (no 32mm carburetors from a 350cc machine, for instance!). You could overbore to .040” and you had to use the stock crankshaft stroke length. Engine modifications for four strokes included pistons, camshafts, valves, racing transmissions (same number of speeds as the street version, though).
The Honda was pretty happy with the 5-speed gearbox, due to the torque of the engine, pulling out of corners. 1973-74 was when the RD125 Yamahas started to appear and once they were ported for power, the low-end torque was gone. It was necessary to “slip the clutch” in slow corners for the Yamaha riders who were carrying those TA125 racing transmissions in their crankcases. One particular machine, ridden by a lady officer of the racing club, was my constant nemesis and I never did defeat her and her heavily-modified RD125. The other bike that only showed up a couple of times was John Ulrich‟s “Killer Deek” 125 DKW Enduro machine. When it was first brought out, it was on par with my bike, but once he had some Sachs engine guru massage it, there was no contest. The bike came with a 6-speed transmission, 30-32mm carburetor and went about 90 mph. Despite the “leading link” front fork suspension, the combination of John‟s riding and the horsepower of the bike overwhelmed to everything else in the class, winning the championship easily in 1975. Because of the number of races I attended and mostly won (including my win at a “one-time” event at Laguna Seca), I scored sufficient points in the class to be the 1974 125cc Production Champion in both the AFM and CMC racing clubs.
I was quite thrilled to have accomplished this feat, using a new $549 street bike, $600 worth of racing parts, a pair of hand me-down leathers and USAF service boots to put a 4-stroke Honda single in the winner‟s circle. For me, my first year of road racing was exciting, rewarding, challenging, scary and weary. Being owner, builder, financier, transporter and racer was more than I had ever done before and the end result was success. I attended the awards dinner in No. California to receive my championship trophy, surprising the group by making the 500-mile trip just for dinner and a cup! It was a pretty wild group and I was glad to have a designated driver, my cousin Suzy, who lived nearby, in my corner.
The results of the 1974 125cc Production class wins.
Tow Vehicles: I had a number of different cars during the year, all of which had to serve as a transportation vehicle for the little Honda. I bought some sturdy bumper mounted racks, designed for motorcycles and strapped them onto an early-70s Toyota Corolla station wagon and a 1949 Cadillac 2-dr fastback, at varying times of the year.
Over the years of moving and getting married, the stash of trophies were all disposed of, but I kept one plaque and my award for being the 125cc Production Championship. It’s been 51 years since my first year of road-racing adventures and most of the people and details have faded away, but I have to say that my uncharted efforts, just to see what it was like, left me with a bit of pride in knowing that you can often achieve your goals if you just keep trying, despite the challenges and obstacles on the path. I saw the potential in the little bike and learned a lot about engine building, tuning and riding at various tracks that are mostly all gone now.
I won races at Carlsbad, Orange County, Riverside, Ontario, Willow Springs and even at Laguna Seca racetracks and only two of those venues are left, now in 2025. I hadn’t planned on continuing to race after the 1974 season, but once the racing bug bites you, it is hard to go back to your pre-racing life, even at this low level. I upgraded the racing experience to 350-400F bikes for a few years, but eventually tragedy struck one of my 6 hr endurance race teammates and in the following year, 1980, I had a BIG get-off that ended my racing efforts completely.
I think everyone has had moments of triumph and a sense of accomplishment in some area of life that should be recognized and held onto deep in your soul as a moment of glory and self-worth. It doesn’t have to be a Championship effort, recognized by your peers and family. Only you know when you have done the right thing and felt the sense of accomplishment and achievement. Carry that memory forward, towards more experiences like that which make life worth living.
Thanks for indulging me, reading my story of the past. I appreciate your feedback and comments. No one really remembers those moments, other than me. Sometimes little snippets come to me in my dreams at night and when I awaken the little voice inside my mind says “Share your story now”! If you are sitting on your own success story, then share it now, before it is too late.
Bill Silver
aka MrHonda
