Continued wrenching on the domestic CL72 went along well, in the early stages, starting with the installation of some spare CB77 shock covers found in a box. The shock body dampers were both still working and not leaking, so the cover installations went smoothly. All that was left of the old shock covers were metal washers, remnants of the original covers which apparently suffered metal fatigue and broke off.
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Next job was to tackle the left carburetor choke arm and replace the o-rings after a cleaning and inspection. Using a MAPP gas torch and some flux/solder, the linkage was mended up enough to resume its place on the carb body. A spare CB77 carb body was disassembled to use the choke arm, but it was discovered that the 26mm carb choke pivot rod length was longer than for a 22mm carb body, so repairs were the order of the day.
The carb internals were in decent shape with #115 main jets installed, so just a quick check of the idle jet, float level and the air bleed passages was all that was required. It was interesting to see that the carburetor bodies were stamped CL72II, although it is unclear as to what other parts might be different from the standard CL72 carbs. Unfortunately, the carbs were rebuilt with Keyster carb kits and the needles have no markings upon them and the originals were not given back with the bike. According to the Japanese parts book listings, the carburetor has a -274-code main jet holder and throttle slide, but no other specifics are given.
My buddy, Scott, whose “endless supply” of Honda 250-305 parts has finally drawn down to a few scraps now, came up with a spare set of “Superior” brand CL72 air filters. Those were installed with the old connector tubes and everything was buttoned up. There was so little gas left in the tank that half of the trip over to the local 7-11 for gas was coasting through parking lots on a dead engine. Once refilled, the bike fired on the first kick and sounded fairly happy. A quick couple of miles of driving proved to be rewarding with a nice transmission function and a happy sounding engine, but on the return up a grade a misfire became evident, so the bike was nursed home for a checkover. After putting it on the centerstand and taking off my helmet, I turned back to the bike and was horrified to see oil dripping off the back side of the engine, drooling down the centerstand legs. #$%TQ$#^!!
Wiping down the oil pools, the search was on to find the “source” of the leak and it was finally traced to oil coming out the breather tube! That is never a good sign, however it really didn’t make sense as the engine does not smoke, the plugs were dry and the compression was excellent. Now what????
The engine top cover nuts showed signs of being removed previously, so the thought was that someone had put the baffle plate in backwards, which causes oil to pool at the top cover and then become expelled during high speed operation. One positive feature about working on the Scramblers is that you can remove the top cover without pulling the motor from the chassis, so that was the next step. Removing the upper motor mount is quick and easy, but that is also where the condenser is mounted. I had an odd spare condenser in stock that was marked for a Dream, but the leads were too short, so I thought it might be for the Type 2 Scrambler instead. With the motor mount out of the way, the 8 cylinder head nuts came off easily and the top cover was then gently pried off the cylinder head… Yuck!
Whatever gasket set was used before had turned into a version of wet cardboard, where it was unsupported and not clamped down firmly between metal surfaces. The gasket separated on both surfaces, tearing apart here and there. Surprisingly, the drain holes in the plate and gasket were in the correct orientation, but it appears that the excess gasket material was blocking drainage and perhaps even the evacuation of the crankcase breather fumes, except in high rpm operation. After the gasket surfaces were cleaned up and new gaskets and a spare clean breather plate installed, the cover was placed back onto the head and all the nuts retorqued. It was obvious that the previous mechanic was not aware that the copper sealing washers go the outside corners, with the steel ones on the inside four studs, as they were all reversed.
The condenser was replaced but the leads were on the short side as well, but long enough to route them safely. There appeared to be some kind of wood/insulation between the coil primary terminals and the frame, stuck in place to help isolate the coil from shorting out. The Type 2 coil is, of course, unique to this model and the mount is welded to the coil case, so there is nothing to do in the way of repositioning it away from the frame, other than elongating the holes. As I was inspecting the coil’s terminals, suddenly one of the spark plug wire connectors separated from the coil connection base! The spark plug wires were held in place by large Bakelite nuts, which screwed onto the coil output terminals, but the terminals were actually adapters which were glued into the coil top surface. I guess the wiser course of action should have been to just try to re-glue the terminal end back onto the coil base, but I tried to unscrew the two parts instead… bad choice. The Bakelite crumbled in my hands and all that was left was a half functional ignition coil with dim possibilities of finding a factory replacement part. Searching the web by the part number turned up ZERO hits. The next step was to hunt down a suitable 12v dual tower coil and adapt it to the frame.
Somewhere, recently, I saw an XS650 coil installed into a Honda Dream, so my search went that direction. Apparently Yamaha did both a single coil and twin coil ignition systems for their 650 twin and the XS650 site had an attractive aftermarket alternative for $39.95! That coil was a 4.5 ohm, 12v unit designed for bikes with points/condenser ignition systems, so it seemed to be a perfect match for my needs. During my web search time, I received an email message from a customer who was looking for a set of OEM Honda needles for his CL77. I wasn’t sure if I had them, but forwarded the message to my mentor/friend Ed Moore, who specializes in Scramblers, but has parts for the other models, as well. I had visited Ed back in 2007 and discovered an odd CL72 Scrambler chassis in his backyard boneyard. It was a big brake model, seldom seen in the US. I had asked him about whether that chassis still had rear turnsignal brackets, because the handlebars had a turnsignal switch mounted up on the right side. It turned out that the bike did have the mounts and a few other bits I needed, so they were earmarked for me once the weather cleared down in Kerrville. Ed emailed a message back to me to call him, which I did to clarify my parts needs for the CL72. In telling him my tale of woe about the dead Type 2 coil, he chimed in and said, “Oh, I have one of those coils!” He was going to build some kind of Type 2 Scrambler on his own and had picked up the coil and saved it for future use. Ed said that he wasn’t going to be able to get around to that project so offered the coil to me for a very reasonable price. Problem solved!
So, until the parts arrive from Texas, the CL72 is on hiatus, resting beneath the bike cover awaiting the spark of life again. Once it is back up and running, the crankcase breather situation can be rechecked and the misfire problems evaluated and corrected, as necessary. I also tracked down a set of OEM Honda Dream points made by Nippon-Denso from a Honda dealer who had an online catalog of their NOS vintage parts. I will change out the Daiichi point set with the N-D versions when I have the coil ready to install. Hopefully, this will have a positive conclusion for all the above-mentioned problems affecting the engine and the ignition systems.
In the meantime, it is back to the 1966 CB77 again for a new battery installation and other minor details.
Bill “MrHonda” Silver