Now that my broken thumb is mostly on the mend, I have been taking in some repair work a little at a time.
This month, two CL77s were in, plus the little CB200T was sold. Now a new challenge has arrived in the form of another SL90 (check old stories for the first oddball version) and as well as a restored CB92 with subtle carb problems. Oh, then there is the sad, but promising 1965 CB77 project recently acquired.
First, the little CB200T with the broken camshaft found a new home in Oceanside, CA about 70 miles away and circumstances created me having to deliver it for a $100 fee. Between replacing the camshaft and the starter switch, and a new front rim/tire. The bike mostly sat in the garage due to the hand injury.
Once the 200T was out of the way, one of my clients who had purchased a 1967 CL77 from an earlier client, brought it back as the spark timing wasn’t returning properly. It would require a cam sprocket replacement, which can be done with the engine still in the chassis, but it isn’t an easy task, The ultimate reason for replacement was that the spark advance return spring was missing! It took several hours to complete the task, but now the engine idle problems are solved. Now, the customer wants the transmission gears X’d and that will be a full engine pull, bottom end tear-down and replacement of the usual parts, including the low gear bushing, no doubt. That one is on HOLD for now.
The next CL77 project came back to me, as the customer reminded me that I had rebuilt the engine when I lived in San Clemente, back in the 1996-2001 era! For some reason, I installed a S12 337cc kit, which now gives 200psi compression readings. The bike was being prepped for sale, and has been mostly revived and repainted. It even still has the old Probe electronic ignition system in place, but needed a full carb cleaning, petcock cleaning, and overall tuning and service work. I couldn’t even pull the clutch lever in due to heavy clutch springs that Honda had specified in later years. Those got tossed and replaced with normal springs, used in CB77s, then the clutch adjuster was replaced with one of the new CMSNL reproduction units. Now I can pull the clutch lever in normally.
Then, the rogue CB77 that was offered to me back when I had a broken hand and was recovering from the Hawk GT650 crash. The bike was abandoned with a friend of a friend of a friend, but did have a clean CA title on non-op status. It had been sitting outdoors, about a mile from the ocean for a couple of years, and was covered in rust and corrosion. With a healed hand, I chased down the players involved and was able to pick it up when I was already in N. County for a chiropractor appointment, which is 40 miles from home.
There is a separate story on the CB77, which at least did turn over and gave the impression that it had been operated in the last few years. I serviced the carbs, recharged the supplied battery and the bike actually fired up and sounded pretty healthy. The over-sized tires were replaced and some fenders acquired to replace the missing ones. The “cafe” handlebars are being replaced with OEM style flat bars and lots of de-rusting will be in the work flow. UPDATE: Sold to an enthusiast in AZ.
Update on the latest SL90 engine project: It took about 3 hours to full disassemble this relatively simple engine. The whole engine was covered in scale and rust to start with and there were non-standard copper washers under the cylinder head nuts. The point cover screws were rusted in place, so needed the use of an impact driver just to access the point plate, which was also corroded. The camshaft had a non-standard looking set of lobes and the valve springs appeared to be some kind of heavy duty racing parts.
Once the cylinder head was removed a GIANT high-dome piston was revealed inside the cylinder. The piston had a groove cutaway on the side to allow for clearance on the spark plug tip. Once the cylinder was removed, it was apparent that this was the biggest 90 piston allowed at 55mm. The bottom of the cylinder wall was 1mm thick. The piston had no signs of actually being used or run in as there was no trace of carbon on the crown. The engine had been sitting with the piston at near TDC, so some rust had formed below it on the bottom of the liner. When engines sit outdoors, untouched for years at a time, whatever oil that was on any parts above the oil level runs off exposing raw steel to the atmosphere inside the crankcases. With changes to temperatures and weather conditions, the air space condenses moisture into water droplets which attach to the exposed steel parts and the rust process develops.
With the top end removed, I attempted to remove the clutch cover screws, using my tried and true vintage impact driver, using various sized hammers. Basically, none of them would budge in spite of repeated blows. The only way to remove them was to use a chisel and notch the edges of the screws, then work on the edges with the chisel and hammer with repeated blows. Slowly, each one finally gave up their grip on the case threads and finally backed out for removal. It took 1 to 2 minutes per screw to remove the clutch cover, only to discover that the asbestos cover gasket was coated with sealant. So obviously someone had been in there previously. In fact, the little cover over the end of the clutch release plate only had one screw instead of two and the screw type was incorrect.
The shift drum detent plate screw was glued in place as well, requiring more demolition work for extraction. Every inside screw needed the same hammer and chisel effort for removal. With the cases split there were rust spots on the outer edges of the crankshaft, near the connecting rod. Only the transmission gears had escaped the rust attacks.
At this point, several options are under consideration. First, just find a decent used engine and start over again, using the old engine cases. Second, replace the monster piston with probably a 12:1 compression rating down to a normal S90 piston and cylinder. The camshaft profile may or may not work as an upgrade to the stock cam. In any case, I have more than 3 hours of pretty intense labor just disassembling this engine and am left with a pile of rusty and corroded parts to show for it.
BTW the carburetor and manifold which had water damage inside the bowl, still had the stock jetting, which never would have worked on the engine combination that was assembled. The cylinder head did show some signs of port work, but it is apparent that the project never reached fruition.
Fortunately, I went onto a S90/CL90/SL90 Facebook forum and saw some engines for sale in Louisana. That lead to a conversation with the owner who is closing out his collection of bikes and parts, including a nice CL90 engine and a whole SL90 engine. He’s willing to ship them to SoCal once we determine which option is the best. It does take a village to get some of these old bikes back into service once again.
UPDATE:
I received a mostly intact CL90 engine from my friend in LA, nicely boxed in a reinforced plastic container. After I extracted it from the mound of peanut packing, the disassembly began. To my surprise, the top end contained a recently re-bored to .25mm piston and cylinder, all in great shape. The disassembly of the cases followed the same path as the first one. All the case screws were seized up in their threads and required repeated blows from a big hammer and chisel to break the thread bonds loose for removal. There are 9 screws in the center cases and it took several minutes per screw to extract each one.
Once the case screws were removed, the case halves were separated carefully and the transmission gears and crankshaft were extracted. Overall, the transmission gears were in fine condition. Again, because of sitting somewhere moist for many years the outside of the shift forks had a fine layer of rust buildup. A combination of rust removal and a wire brush cleaned them up for re-use. The inner cheeks of the crankshaft were also freckled with surface rust and were also cleaned with similar results.
Starting with the newly vapor blasted engine cases, I removed the existing transmission bearings which had been contaminated with vapor blast media and swapped them with the CL90 bearings. A new seal was installed in the left case half and reassembly of the transmission and shift fork unit was performed. The crankshaft was installed in the left case and a new gasket laid down. Gently the cases were reassembled but the kickstarter gear engagement with the transmission caused some difficulty, until the engagement was completed by turning the kickstarter shaft slightly and pushing the cases back together again. I had a set of leftover new case screws available from the last engine build, so was able to snug the cases together.
The next step was to disassemble the cylinder head and clean the valves. Another trip to the vapor blast shop had it looking fresh again, along with the cylinder which was stripped of the original black paint. The cylinder was taped up for a fresh coat of paint. The cleaned up valves, which showed nice seating patterns were reinstalled. On the 90 engine the intake valve was fitted with a small valve stem seal. The head was reassembled and then the rest of the engine began the assembly process.
The engine cases go together but with some tricky business to get the kickstarter shaft and gears to nest into each other so the cases will fit up properly. All the transmission gears were in good shape. The camchain tensioner roller needed to be replaced, but the rest of it slowly found its way back together again.
The SL90 carburetor is pretty unique and all the carb kits that were offered were of the S/CL90 style float valve which is not used on the SL90 engine. After some research, I found that the carb kits for the XL/SL70 used the same float valve, so that finally solved the problem. The float bowl was plastered with JB Weld and after being vapor blasted, a hole was found in the bottom of the bowl. More JB-Weld was employed to help seal it all up again.
You have to remember to install the camsprocket on the chain before you put the cylinder head back on the motor. It’s all a little puzzle of parts that go back together in a specific sequence. I discovered that the rubber packing gasket B came in two types with the aftermarket kit. When I had filled the engine with oil, a leak was discovered coming out of the camchain chamber and around this gasket. The chamber area is not a rectangular shape, but bows out on the outside. I wound up using the piece that was in the engine previously that had the correct shape to prevent any oil leaks.
Fortunately, the replacement cylinder and piston were ready to install after a bit of cleaning. It’s hard to find shops that will do boring of small displacement engines here in San Diego, so we saved time and money with the Louisana CL90 motor. Tearing two of these motors down to make one takes a good bit of time and effort, but it is looking good for installation now.
Bill Silver aka MrHonda www.vintagehonda.com
PS
I’m finding that those green “non-asbestos” gaskets from Thailand and elsewhere are seeping oil out of the gasket material. Am I the only one that has noticed this problem?
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