Wednesday, November 24, 2021

What? Not again… another CB77 rescue

The past few months, it seems that all the local lame and wounded vintage Hondas have found their way to my little messy shop for repair and rejuvenation. Having been embroiled in a pair of “beach bike” CB350s, suddenly a sad, but salvageable later-model CB77 pops on Facebook forums as a project bike with a seriously seized engine. Seller was taking offers and finally settled on mine. All I had to do is drive 150 miles up the road to fetch it and bring home the remains for revival. Very few CB77s have shown up in SoCal in the past year, so I guess you have to go out and haul them in if you want to own one again.

I already have my low-budget 1963 CB77, which was a bike I pieced together 6-7 years ago, then let it go to a woman who lost her garage space and sold it to her girlfriend. She rode it out to Joshua Tree from San Diego on a woman’s ride, making the journey safely, but the bike was seeping oil out of the tachometer cable seal and she parked it in 2016. I wound up buying it back and putting it back into regular service now and was happy to have it for my runs to the post office and local trips.

Over the past year or so, I have snagged bits and pieces of Super Hawks, either to keep for emergencies or to put a little stash together in case a bike like this new one shows up for repairs. I have collected a kickstarter cover, cylinders, cylinder heads, valves, wiring harness and NOS ignition switch along with a lot of other little tidbits. So, now it looks like they will be put into play for the latest project.

The pickup adventure…

Leaving at 8:30 AM gave me about 3 hours to cover 150 miles up to and beyond LA. Waze GPS app took me off the I-5 once, across the 91W to the 605N, then back to the I-5 again. I have learned to trust it and sure enough, the bulk of the journey north went smoothly and I was there in 3 hours flat.

I gave the bike a quick once-over, noting that the cylinders were full of rust and the tank had stalactites inside once the cap was removed. It would appear that the cap was left off and the bike left outside to collect rainwater, which flowed into the open petcock, filled the carburetor bowls, then traveled down the right side cylinder’s open intake valve.

The bike only had 12k miles showing and was a 18K series 1965 model with an array of little mods including chromed fenders (front one chopped off), chromed side covers, transmission cover, footpegs and horn cover. The bike did have OEM exhaust pipes, but one muffler looked rusted out on the inside, also on the right side.

We loaded it up, I left a copy of my Classic Honda Motorcycles for Dave and the shop guys and hit the highway once again. The return leg had me headed down the I-5, then east on the I-10, then down the 710, then back to the I-5 again. In the end, the Tacoma covered 340 miles in 6.15 hours getting 26.4 mpg on the way as we tooled down the highway at 80 mph for much of the return trip.

Once the bike was unloaded, I hauled the engine up on the workbench and filled the cylinders first with Metal Rescue and Kroil, but switched to straight Metal Prep (phosphoric acid) after trying to loosen the pistons with my little steering wheel puller (as a pusher) tool attempt.

                                                           How it started out...

The next day…

Popping the float bowls off the carburetors revealed massive amounts of water damage corrosion to both carbs and the petcock. Metal was etched away on one carb main jet holder area and the petcock had a pinhole at the top where the metal had been eaten away. Fortunately, I had a spare set of square bowl carburetor bodies that should be good enough to bring the bike back to life again, once everything is put back together.

I ordered $100 worth of bits from and a new AGM MotoBatt battery from an eBay supplier.

I filled the gas tank with ¾ gallon of Metal Prep, let it sit for awhile then added water to the top opening and will let it sit for a few days. Hopefully, the pistons will loosen up and I can continue with the engine rebuild without resorting to violence on the piston crowns.

The worst one ever…

Using my steering wheel puller tool as a piston pusher, the pistons refused to budge, especially the left side one which was near TDC. The right side finally moved slightly, which just raised the cylinders off the crankcases ever so slightly. More pressure on the left side resulted in a loud crack and the top of the cylinder liner snapped off. The liner/piston combo could only go down so far before hitting the crankshaft, so this strategy wasn’t really working out. All I could do was totally destroy the cylinder block in order to remove the pistons from the crankshaft.

First, I took a hacksaw and sawed the cylinder block in half through the camchain cavity. Then, I had to pull the whole bottom end off the bench and over to my air compressor where I used an air chisel to pound out the right side piston from the sleeve. Next, the left side sleeve was pushed off the cylinder casting, leaving it intact and hanging from the connecting rod. I gathered it back up and put it back on the workbench, then attacked the sleeve with a Dremel tool with a cutoff wheel(s). Cutting down both sides of the sleeve about halfway allowed me to split the sleeve with a chisel, revealing a fully rusted piston from top to bottom and rust below the piston in the sleeve as well. I have never seen so much corrosion buildup between the piston and sleeve on a water-seized engine before.

The piston was finally clear of the cylinder sleeve, but we weren’t done just yet! Using a very big piston pin pusher tool, the pin was stubbornly stuck in the piston pin bores. I had to break out the Dremel tool again and cut the piston apart through the pin bore which finally relaxed enough to release the pin and the rest of the piston. I figure that it took about 6 hours of labor just to remove the pistons and cylinders from the crankcase and crankshaft. Worst one ever….

The cylinder head combustion chamber on the right side was pitted from years of standing water on that side, so it went to the scrap heap, as well. I continued to dismantle the rest of the engine in order to clean out all the debris from the piston removal process and check over the transmission and kickstarter parts. Fortunately, the bottom end was pretty clean and just needed a lot of washing of parts in order to clear the leftovers from the piston destruction process.

The whole outside of the engine was covered in layers of grease, dirt, oil, corrosion that took plenty of time just to scrape off the worst of it. I discovered a local shop that had a vapor blaster machine and was willing to clean the parts properly. Everything came back looking like fresh alloy, but needed a second cleaning/rinsing to clear leftover glass bead debris from the cleaning process. Now I could start to rebuild the engine using nice clean parts.

The spare cylinder head had good seats for the valves, only needing a little pass with the valve seat cutters to make nice shiny little circles in the cast-iron skull that comprises the combustion chamber, valve seats and spark plug hole. I installed a new set of valves with the original valve springs which had blue paint on the ends, which I had never noticed before on CB engines.

The spare cylinders on hand were still at STD bore, but one side had a single scratch down the side, but below the top couple of inches of piston travel. I cleaned up a set of STD pistons and rings that were hiding in a box and set about putting the whole top end back together with replacement parts from stock. The bottom end really didn’t need much in the way of replacements, apart from the kickstarter pawl which was somewhat rounded off on the contact surface.

Reassembly of these engines takes more time than you would expect, especially when each part needs to be cleaned and evaluated for re-use. I spent a couple of afternoons cleaning and assembling all the bits and pieces until I had a gleaming shiny engine assembly sitting on the bench. Next step, the chassis..

I spent a good part of a day first removing the front wheel and forks in order to replace the left side upper fork ear, which was flattened out from some impact. I was able to get a NOS part from for $65, which came in factory primer, so needed a coat of black paint to match the rest of the bike. While apart, I cleaned the fork seal holders and the chromed trim rings which had some pitting, but were good enough for the moment.

Invariably, the brake cams on these bikes are all sticky from 50-year-old grease and the intrusion of moisture over the years, so they must be dismantled, cleaned and lubricated. Honda didn’t make it very easy to dismantle the brake plates, as the brake shoe pivot bolts are held into the plate with nuts on the outside which have little punch mark stakes in two places. There is no room to get a socket onto the nuts, so I went in from the backside and used an air tool to break the 19mm head bolts loose from the 17mm nuts on the outside. Once apart, I replaced the front shoes with new aftermarket Vesrah brand replacements, which are non-asbestos materials. The original 5mm shoe thickness was worn down to about 4.3mm on the front and 3.4mm on the rears. I wound up using the used front shoes on the rear brakes in the end.

Both brake drums were rusted, as expected, but a half hour of cleaning with a drill motor and small wire wheel eventually removes all the rust and scale from the drums. More time was spent cleaning the rims with 0000 steel wool, just to make them look a little more presentable. The whole bike was just dirty and corroded to a degree, but Honda’s chrome was of pretty good quality and a lot of the original finishes came back up pretty well.

The bobbed front fender, which had been chromed was a problem to solve. I discovered an eBay vendor who had some of the Japanese made replacement fenders which I have seen before on other bikes in the past. The front fenders on CBs come in two versions, depending upon how they mount to the forks. This early bike has the steel fork sliders, so needs the early hockey stick type of center mounting ears. I knew that it wasn’t really the best option but at $100 it seemed like a good temporary fix for the front fender situation. The fender arrived quickly, but the troubles were just beginning.

For all appearances, the fender should have bolted up to the forks, as planned, but when the locating pins were pushed into the fender stay pads, the bolt holes were off about half a hole diameter. Well, that was weird, but perhaps they just had a bad day at the factory back then, I thought. Unfortunately, the more I whittled on the fender mounting hardware, the more it seemed like this was really NOT designed for this bike! The fender sits up about 2” above the tire and neither of the fender stays come within 2” of connecting to the fork slider. The curvature seems a little off, as well, perhaps due to the possibility that the fender was designed for a 19” wheel not the 18” wheel of a CB77. So, I really don’t know what this fender was destined for but it doesn’t appear to be for a Super Hawk model. The only other fender of that type of mounting system is the early CB450K0 Black Bombers, but I was never aware that there were aftermarket fenders designed for that model. So, no I am stuck with an ugly $100 fender that doesn’t work at all on this bike and is so carved up that it can’t be returned now. Interesting lesson learned here…

Next up, the marriage…

The chassis needed a good scrubbing to clear off years of dirt, oil and corrosion, so it got a good bath before the engine was reinstalled into its original place. Once cleaned off, there are still many hours of work to do in order to make this machine come back to life again.

As in interesting sidelight, the guy who did my vapor blasting had a black CB77 rolling chassis with motor sitting on a second level floor, just kind of hanging out there. It had a seat and fuel tank, which I needed for the LA bike, so I asked about it. The owner said, “You sold me that bike for $100 years ago and you can have it back for $100.” So, I added $100 to the bill and brought back yet another CB77 to make it a trio at the house for now.

Fired up, but leaking oil…

The engine started up on the first few turns, coughing and smoking out the mufflers for a few minutes. A few oil drips showed up quickly on both cylinder head covers, probably due to my reuse of the parts that still had the original gaskets. They looked good enough to reuse, but they were hard and just didn’t seal well. I replaced both cover gaskets, which cured the oil leaks there, but a more serious one materialized at the middle of the brand new head gasket. The head gasket was from an aftermarket company with little dimples across the surfaces. I don’t know what happened there, but it was disappointing to see and required another engine removal to replace the gasket and check the o-rings for sealing. The o-rings are supposed to be 2mm thick, but some of the aftermarket versions seem to be closer to 1.75mm. Digging into a Harbor Freight box of Viton o-rings, I came up with some that were about 2.4mm thick, so I opted to use those instead. I also coated the inside of the o-ring holes in the head gasket with some liquid sealer to prevent oil migration laterally through the gasket material. I coated the gasket with Gasket-Cinch and let it set up before installing the gasket and cylinder head.

Using a hydraulic bike lift to help handle the engine assembly made it a bit easier on my aging spine, but I still have to lift it up/down about a foot from the bench to the lift. I always feel it the next day or two, though. It winds up being a good 3-4 hour job to manually dismantle the bike’s external parts and ease the motor down and out of the frame. A good hour or so was spent on the bench, dismantling the cylinder head from the engine and cleaning, inspecting, gasket scraping, and prepping the parts for reassembly. Then, it is back onto the lift and back over to the frame. Unlike the Scramblers, the Super Hawk engines go straight up into the frame from the bottom, so jockeying it around and into the mounting points is much less of a strain on the old bones.

Fired up 2.0...

Once the bike was nearly back together again, the engine was test-fired to verify that the head gasket leak was solved and everything was back to specs again. For almost all of the CB77s that have come my way, I have installed #140 main jets to compensate for the alcohol in today’s fuel supplies. This setup in my 1963 CB77 works flawlessly, with easy cold starts and smooth fuel delivery all the way to redline. This 1965 bike wasn’t having any of that...

First, the bike sounded like it was running very rich at mid-range and spitting back through the left carburetor off-idle, which is a confusing combination of symptoms. I discovered that once the fuel tank was cinched down onto the frame, apparently the throttle cable was getting pinched off somehow and the carb synch was WAY OFF. The left side was lifting 1/4” before the right side started up. It wasn’t making much sense as the new cable was used and the carb slides and adjusters were matching height at first. When the fuel tank was loosened up, the carb synch issues swapped sides! Pushing the parts around finally got the cables to match up normally and the carb synch was restored. I had installed a set of OEM carb needles and have moved the needle clips up and down, trying to find the happy place for the engine.

Finally, I swapped out the #140 mains for a set of stock #135s and the engine began to smooth out through the rev range. The ignition timing was rechecked using an automotive timing light and it was discovered that when both sides were setup at the F mark at idle, the wear inside of the camsprocket advancer weight pads have compressed somewhat which creates excessive spark timing at full advance. I have found that you MUST contain the spark advance to stay close to the II marks on the rotor at full advance. Setting the spark advance timing to that limit yielded idle spark timing at the T mark instead of the F mark.

My friend Tim Miller, down in TX, dismantles the camsprockets and modifies the spark advance curves so that they have about 10 degrees less total timing advance, but this allows the engines to run about 10 degrees BTDC at idle, which is where they really like to be. If the engine has to come down again in the future, I will ship the camsprocket out to Tim for rebuilding.

A few local test rides are showing promise as the engine beds in and the carbon and oil is all burned out of the exhaust system. The engine compression readings are right at 160 psi on both sides, which is about normal for the later lower compression piston setups that Honda used after 1965.

Some of the big-ticket items for this revival included nearly $400 just for vapor blasting the engine components, $65 for the AGM battery, then another $50 just for the battery hold-down plate and cushion, $60 for a new drive chain, $65 for a set of mirrors, $155 for a set of cables to replace the original tach, speedo, clutch, front brake, rear brake and throttle units. I used the gas tank from the newly acquired $100 parts bike, which needed a $160 clean and seal, then a $125 black paint job. I added one of my little Dream 50 tail light lenses, which are an inch and a half shorter than the regular long lens used on all of the 1963-66 models. The stock right-side muffler had a section that was rusted through in one spot which required a $50 welding job. The speedometer went haywire on the first drive, so $275 was spent on getting the meters rebuilt at Foreign Speedometer here in San Diego. I picked up an aftermarket blue seat from my friend in TN who brought it to the Barber Vintage Festival in Oct. $90 including shipping back to San Diego. The original seat pan was poorly repaired with someone with an arc welder, instead of a TIG welder. Aftermarket copy seat bolts set me back another $20.

The spare cylinder head got a new set of valves which run about $100, then gaskets and seals add another $80 to the mix. I already had a spare set of cylinders, STD pistons/rings that were used but good enough to put together with confidence. The head and cylinders/pistons would have run another $250 if I had to purchase them elsewhere. Tim McDowell supplied a set of aftermarket air filters, air tubes speedometer packing, and other bits that ran up another $200. The carburetors needed kit parts and floats, so $80 more to the total. The new CA title costs $55 plus 2 trips to DMV and one to CHP offices for inspection and VIN verification appointments. After awhile, you step back and gasp at all of the money spent just to get a bike like this from parts bike status to a full running motorcycle again. The parts bills can easily run to $2k especially if you have to buy new pistons/rings and then bore the cylinders for $90 to machine two cylinders. And don’t ask about the hours invested in all the steps to clean, repair and assemble the whole bike again…

In the process of rebuilding the bike, which still has the original paint and all of the extra chromed parts attached, the former owner of my 1963 bike (which I bought back from her a few months ago) fed me a referral to an interested buyer for the 1965 bike. He brought his 12-year-old son with him and even though the bike wasn’t quite finished, then had a flat tire, but he was enamored with it and wished to buy it when everything is complete.

So, in less than 2 months, the very dead CB77 is now back on its wheels, with a running, rebuilt engine and a promising future with a new family who plan to keep it as an heirloom to be passed down to the next generation in years to come. The end result makes all the labor and expenses worthwhile.

                                                                   THE END...

Bill “MrHonda” Silver



  1. thank you for a brillant read, and saving another of these great bikes.

    (and reminding me to send a check to Tim Miller, who is working on a project for me)

  2. Entertaining as usual
    Really interesting as I am restoring my 2nd Super hawk (actually purchased some parts from you for it)Had to redo the top end on my Red 65 first and just got it back in the frame yesterday and started.Like you,had an oil leak but much simpler....clutch rod seal.Seems I replaced this before but it still meant removing rs exhaust and wait for the part.Bought one with a collar built around it.Hope thats an improvement.ALWAYS SOMETHING but its still fun

  3. Always a pleasure to read these stories!