Enough of the excuses … here’s the latest. Over the past few days I’ve completed the truing of the wheels and have mounted the new tires. Once I find my set of balancing weights, I’ll balance the wheels. 2 years ago the hubs were vapor blasted and look like new. Also, the stainless steel spokes are a nice upgrade from stock. The hubs have new bearings pressed in as well. The aluminum rims are from Borrani in Italy and match the flanged style of the original steel rims.

The new old stock (NOS) engine side covers got several coats of ceramic aluminum engine paint, followed by a heat treatment. The original covers had damage and needed replacing. The right side cover is hard to find, too, as it contains a cast-in kick starter shaft bushing, which tended to wear over the decades on these kick start-only bikes.

I’ll focus on completing the frame pieces and panels that will be painted their original light silver. I’ll get the sanding and prep work done next. Since the warm weather is fading, I’ll outsource the painting to the pros, which will allow me to put the engine back together during that time.

My goal is to work on this during the off-season and have it ready to ride when the snow clears in Spring 2021.

I will return the motorcycle to its original light silver color, so the non-standard blue paint had to come off.  For this work I used Aircraft brand paint remover.  This blue paint was rock hard and initially resisted the paint remover, so I had to lightly sand the surfaces to allow the paint remover to do its work.  The paint eventually surrendered and flaked off as expected.  At this point I discovered a few areas with very thin body filler under the paint.  The paint remover also removed the body filler, so I’ll need to fix that before priming the panels.

I also began the process of reassembling the engine.  The alternator rotor needed to come off, which required an M16 1.5 fine thread pitch bolt to be screwed into the rotor.  My local hardware store only stocked M16 2.0 standard thread pitch bolts, so I had to order a single bolt online.  Armed with my special bolt, the alternator rotor easily popped off as I threaded the bolt into the rotor.  This allowed the old crankshaft seal to finally be removed.

I disassembled all the transmission pieces, cleaning each piece with solvent before reassembling them with engine assembly lube.  The engine assembly lube has graphite and molybdenum to aid in lubricating the engine during the initial start-up, before the oil has a chance to circulate the first time.  I was quite pleased with the condition of the transmission gears.  I wasn’t able to find a single tooth that exhibited any visible wear.  The gear “dogs”, which engage the gears when the transmission is shifted, looked like new, without the slightest rounding.  This transmission should shift nicely.

The crankshaft was cleaned and the bearings lubricated before being set into the crankcase.  The camshaft drive chain was installed at this stage.  All engine seals were replaced as I reassembled the engine’s lower end.  I stopped at this point but will pick up next time with the installation of the pistons, cylinder and head.

I used a graphite-moly engine assembly lube during reassembly.  It only took about 10 minutes to reassemble.  This oil pump body also contains the oil drain bolt.  The original drain bolt was previously chewed up by earlier owners that apparently had only a pliers in the tool box.  I replaced this with a new zinc chromate plated magnetic drain plug.

I will soon be reassembling the engine.  I have ordered the M16 1.5 pitch bolt I need to remove the alternator rotor from the crankshaft, after which I can remove the old seal and re-lubricate the bearings before reassembly.

Today I finished rebuilding the carburetors.  It’s a fairly simple process, made easier since the carburetor bodies were cleaned with the vapor honing process I covered in my January 29 post.  The carburetor rebuild kit included parts specific to this model of motorcycle, so reassembling the carburetors was easy work.

The carburetor rebuild kit included new brass jets, springs, gaskets, o-rings, float bowl valves and adjustment screws for both carburetors.  The adjustment screws and throttle jet needles were set to the default setting, which should be fine for starting the engine.  Once the engine warms up and breaks in for at least 50 miles, I’ll go through the process of setting the adjustments to balance the carburetors and fine-tune the settings for a smooth idle.

I have all the engine parts needed to begin reassembly, so stay tuned.

Replacing wheel bearings is normally a quick process, but as luck would have it, one bearing came apart during removal, leaving the outer bearing race stuck in the hub.  Furthermore, the three screws that secured the bearing retainer had stripped heads and needed to be drilled out.  That’s never fun.

Fortunately, drilling out the screws was fairly easy with the drill press.  I then used a large screw extractor to bite into the screw and unscrew the remaining screw material.  All three backed out fairly easily.  The threads in all three holes are in excellent shape, so no new tapping is required.  That’s one problem out of the way.

On the same hub I still had to remove the stuck outer bearing race.  There was no edge or lip exposed from inside the hub, so I couldn’t pound it out from the opposite side.  My only option was to cut it out with a rotary tool fitted with a small abrasive cutting blade.  The tool cut into the hard steel race with no issues.  I was careful to avoid cutting into the aluminum hub.  After a few minutes of cutting, I was able to pry the two halves of the bearing race out of the hub.

I heated the hubs to around 400 degrees in order to expand them, making it easier to press the bearings in.  The bearings were frozen, to contract them a bit, also to aid in pressing them into the hub.  All 4 bearings were easily pressed in, and they roll as smooth as silk.  These hubs are ready for lacing once the rims arrive.

The results are incredible, and my parts look as good as when they were first cast over 50 years ago.  It will be like building an engine from new parts.  Vapor Honing has gained favor in the automotive and motorcycle restoration business, in addition to firearms restoration.  The results speak for themselves.

In another example of overkill, these forged aluminum pistons from Wiseco are designed for high-performance applications, but are lighter and stronger than the stock cast aluminum pistons.  The new iron cylinder liners will be installed in the cylinder block after I have it media blasted to clean away decades of oxidation and grime.  The cylinders will then be bored and honed by a machine shop to fit the new pistons.

I’ll be taking the engine block castings, cylinder and head to a media blasting company in January.  I want to be reassembling the engine in February to stay on track.  As always, I’ll post updates when progress is made.

Typical for Honda engines of the period, there is no external oil filter, but instead a centrifugal oil “slinger” which removes particles from the oil by spinning a finned chamber at high speeds, causing the particles to be thrown to the outside of the chamber instead of circulating through the engine.  There was a heavy accumulation of crud in the chamber when I opened it, which required heavy scraping to remove.  I suspect that this chamber wasn’t cleaned with any regularity, if ever.

I have yet to clean all the head parts, but so far I’m pleased with their condition.  The valves look great, as do the valve seats.  At this point I plan to clean and lightly lap the valves into their seats during reassembly.  The valve guides are also in excellent condition.  After taking measurements with a micrometer, the camshafts are all within spec, and at the high end of the range, too.  I already have a new camshaft chain, so I didn’t bother measuring the original.

I’ve removed the iron cylinder sleeves, and will simply retire them.  I’ve ordered new forged pistons and iron cylinder sleeves, which should arrive by the end of the year.  The engines cases, cylinder block and head still need to be cleaned and either bead blasted or vapor blasted to return them to original appearance, after which I’ll have the cylinders machined and honed to fit the new pistons.

These engine rebuilds are lot of fun.  I’ll post updates as progress is made.

It took about 2 hours to take the engine apart.  Like other Japanese motorcycle engines of the era, there were quite a few Phillips screws used to assemble the engine.  Roughly half of these screws loosened with the hand-held impact screwdriver, but the other half turned to mush and required drilling.  This means I’ll need to extract the remnants of those screws before the engine goes back together.  Although I’m aiming for an authentic restoration with this project, I will not be using Phillips screws when the engine goes back together.  These will be replaced with Allen-socket button head screws.

These engines were known to wear out the kick-start bushings, so I’ll press in new bronze bushings.  The transmission gears were in excellent condition, including the engagement “dogs”, of which none showed any signs of rounding.  I haven’t taken any measurements of the transmission shaft bushings, but I’ll replace anything out of spec.

One small surprise was a hairline crack in the upper engine case.  Oddly, the crack is only visible from the inside of the upper crankcase, not from the outside.  I have a spare upper engine crankcase that I could use as a replacement if necessary.  I had intended on retaining the original upper case to preserve the relationship between the frame serial number and the engine serial number, but I may have to use the spare upper crankcase anyway.  The lower crankcase will not be reused, as the lower right casting was broken away and missing.  The replacement lower crankcase is in good condition and all sections are intact.

The cylinders appear to be in good condition, but I expect to replace the cylinder liners anyway since my plan is to also replace the original cast aluminum pistons with stronger aftermarket forged aluminum pistons.  That will require the cylinders to be machined to fit the new pistons, so it only makes sense to replace the cylinder liners too.

The most difficult parts to get are replacement chains, and inside this engine, there are a bunch.  The centrifugal oil filter is driven by a tiny chain.  The overhead camshaft is chain-driven, and the engine’s primary chain, which connects the crankshaft to the clutch and transmission, is a noted weak point, good for roughly 10,000 miles.  This bike has 19,000 miles on it.  I’ll have to do some research on replacement chains, and take measurements of the existing chains to determine their condition.  The primary chain tensioner wheel is aged and the rubber is cracking, so that can’t be reused.  Same with the camshaft chain tensioner.  I’ll look for aftermarket options and do some research.

During this Winter I’ll continue to work on the engine.  I have some parts to hunt down.  I’d like to be reassembling the Scrambler in the Spring of 2018, so I have to get busy!

That said, my neighbor Don decided that I was just the right person to take ownership of his “baby”.  He priced it low, too, after I had initially passed on the offer.  Sure, twist my arm, Don.  Today, the 1966 Honda CL77 Scrambler was rolled into my garage, waiting in line for its turn for a rebuild.

The Honda CL77 Scrambler was a 305 cc twin-cylinder motorcycle made from 1965-1967, although some bikes made in this period were titled with a later model year.  Like most 50+ year old motorcycles, this example has accumulated a fair number of modifications that I’ll need to correct to bring it back to near-original condition.

While the vibrant blue paint is well done and striking, it’s totally wrong for this machine, which came from the factory with a light silver color on the fuel tank, fenders and side covers.  Since the CL77 had at least some light-duty off-road inclinations, I found it rather odd that a previous owner added “highway pegs” to the front, allowing the legs to rest straight forward as with a chopper-style bike.  Likewise, the handlebar is a tall, cruiser-style mini ape-hanger that looks out of place here.  The seat was unprofessionally re-covered at some point and looks like a tall sack of potting soil, so that will go, too.

Some changes I’ll be making will be to improve reliability and durability.  This engine used a twin set of points in the ignition, so I’ve already acquired a nice electronic ignition module to replace it.  Once the ignition timing is set, I’ll never have to touch it again.  Electronic ignitions, with their modern circuitry, require a fairly constant, spike-free voltage level, and this CL77 didn’t come with a voltage regulator.  I’ll install a combination voltage regulator/rectifier that is matched to this model’s alternator.  The original ignition coils will be replaced with high-output coils that will produce 2 to 3 times the voltage at the spark plugs, improving starting and engine performance.

I’ll replace the wheel bearings, but the wheels and spokes are in great condition, and the tires were replaced 2 years ago, so those will stay.  Gaskets and seals will get the usual attention, and because they are cheap, all the cables will be replaced.

Fortunately, I should be able to clean and re-use the exhaust pieces.  That’s good, because as motorcyclists like to say, this exhaust system is made from “unobtanium” and when good pieces do show up online, they get bid into crazy price levels.  While it may be possible to replace the high-rise exhaust with a standard low set of pipes from the CB77, it would obliterate the key feature which defines a Scrambler, so I’ll do everything I can to retain this exhaust.

With travel planned for April and May, and the Dnepr waiting to be completed, I expect to start this CL77 rebuild later in the Summer.  I’ll post the updates here.