Reviving a Honda CL350

Discover the love of improving classic bikes with time and care while reviving a Honda CL350 by applying problem-solving skills.

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by John L. Stein

You know how occasionally, someone says something that’s obvious to everyone but yourself? Years ago, a girlfriend commented (most likely while watching her BF grapple with a derelict car repair), “You know, I’ve never seen you happier than when something’s broken.” That offhanded compliment stuck with me for years, but its oddity also gnawed at me.

Because, what did she mean exactly — that I’m some moto-bumpkin who doesn’t know that life is better when you buy new things on the E-Z Pay Plan, that always work as advertised? Or was it just an innocent observation, from her disinterested-in-mechanical-stuff standpoint, about her guy’s penchant for mechanical pain? Hopefully it was only the latter, but many times it’s made me wonder — not just about myself, but about other people who like classic bikes and cars, and the more broken the better. Such as the 1973 Honda CL350 Scrambler shown here … beautifully original but lame with a sour cylinder and needing love.

A case for broken bikes

Are such classic bikes actually physical manifestations of Greek mythology, like wheeled descendants of Centaur who’ve selected hosts … us … to fulfill their mission? Maybe that’s a little far-fetched (unless you’re quarantined with a bottle of Patrón), so here’s another possibility: Fixing classic motorcycles makes us feel good, because applying problem-solving, tool skills and persistence can transition them from lumps of useless metal into rolling art that can also serve a functional role in our lives — the joy of riding. And maybe also, resale.

As my Cycle magazine editor Phil Schilling counseled, we feel good about old motorcycles because while new bikes can only go downhill with miles and years, classic bikes — especially original ones found in non-running condition — actually improve with time and care. Any decent shrink will confirm that you feel better with accomplishment, and so adopting old bikes is a useful tonic, especially in trying times.

Pretty, and pretty tortured

All of which brings us to the aforementioned CL350. Owned previously by creative director Napper Tandy, this is to me the prettiest of Honda’s CLs. With its racy upswept chromed exhausts and heat shields, cross-braced handlebar, dual gauges — still the delicate small ones — a slim 2.4-gallon fuel tank, and a dashing red and white paint scheme, the CL was breathtakingly beautiful. As Napper explained on the phone, his friend took it for a ride, the engine went “Bang!” and then — as Rolls-Royce once proffered — “failed to proceed.” But that’s about all he knew. And since Napper already had a vintage dirt bike, an Alfa Romeo and a pair of International trucks, he scarcely needed a fifth project.

But he could easily explain his original attraction to the Scrambler. “I have a passion for the vintage aesthetic of the 1960s and 1970s,” he said. “The CL fell into my lap via someone at work, who was looking to sell the old girl. I took one look and it screamed ‘vintage scrambler’ so I shook his hand and the deed was done.” But once the damage was done, he needed to sell, and while I didn’t need another bike, my heart opened instantly for the Honda.

Personal power

In simple terms, this article, the first of two parts by the way, is my proposition that acquiring broken classic motorcycles is a good thing to do, for several reasons. One, our skill sets broaden when we take on, struggle with and ultimately solve puzzles we don’t understand and aren’t even sure we can do. “You don’t know how high you can go until you can’t get back down; you don’t know how deep you can ride until you can’t get back out” wrote motorcycle photographer and filmmaker Bill Delaney in 1976’s seminal surfing movie Free Ride. So true with bikes too!

And so, it is empowering — in theory at least — to adopt a bike that’s broken, or even just a non-runner. There are surely thousands, if not tens or even hundreds of thousands, of them out there. Additionally, such projects can build camaraderie with other interested parties, turn useless hulks into ridable, useful bikes, and maybe even save money or make a bit on the project.

Make a plan

It’s easy enough to just dive in, take something apart, and hope and believe that, somehow, you’ll find your way — like a rat bumping through a maze — to the other side. Fine if true. But being a logical sort, and having much experience with Bikes That Won’t Run, I feel that dividing a project into manageable phases or steps is easiest, calmest and best. And with this Honda CL350, I wanted it to serve a function by introducing people who might otherwise hesitate, bypass or avoid such projects, to stop by and immerse in this one. Thankfully previous owner Napper; Amanda Clapp, a doctoral student in psychoanalytic psychology; and my son Derek, a psychology undergrad, all wanted to help.

When I met Napper to inspect the bike, he had already removed the right-hand spark plug. It seemed normal except that the tip — the part that lives inside the combustion chamber — looked like Krakatoa circa 1883. Utter devastation, with the porcelain and both electrodes gone, the steel shell smashed and the center embedded with fragged steel and aluminum. With the Honda almost a half-century out of warranty (!), the problem would be all mine.

I paid the man, we pushed the Scrambler into my pickup, and I headed home, hatching a plan and hoping for the best.

A clean machine

Having worked on dirty motorcycles and clean ones, on new bikes and machines now 105 years old, I can report that in all cases, it’s more satisfying and offers a better outcome to start with a clean bike. Washing the Honda was satisfying because within 20 minutes, what had been a dirty and broken motorcycle turned into a gleaming and broken motorcycle. See, an improvement already!

Appropriately, this needed magic happened with a few choice Pro Honda products. One was aerosol Chain Cleaner, which emulsifies grease and grime on the chain, swingarm and chain guard, allowing it to be hosed off. Another was Hondabrite, a spray-on cleaner safe for virtually all motorcycle surfaces, from plastic instruments to vinyl seats, tire rubber, paint and plating. Wet bike, spray on product, hose off grime, towel dry. Simple. Following came a light coating of HP Chain Lube, while Pro Honda’s Spray Cleaner & Polish added some welcome shine.

Diagnose it

It was exciting to see a little group organically form to diagnose the Honda’s woes, a rewarding initial goal. Amanda already owned the 1969 Suzuki TS250 used in It Don’t Come Easy (Motorcycle Classics, March/April 2018). And having struggled with that bike’s fuel system, she was keen to learn new skills courtesy of the Honda. “I can’t say my interest in either my Suzuki or this Honda is nostalgia, because they’re both way older than me,” she admitted. “Instead, I like the simple mechanics, the sound, and the joy of stewardship over a well-crafted piece of machinery which has a lifespan that’s potentially limitless and determined by the quality of our care.”

In case you’re wondering how a millennial female Ph.D. candidate became interested in old bikes, here’s Amanda’s pathway. “Growing up in the country, I was surrounded by motorized vehicles,” she explained. “I started riding our family ATV through orchards, creek beds and gravel quarries when I was 10, and also experienced my brother’s Honda 80 dirt bike and some Trail 70s. When I was 19, I got my motorcycle license so I could ride a Yamaha Vino 125 during college. Then later, a boyfriend who collected vintage bikes really got me into riding. I rode his ’70s Kawasaki KZ400 one summer and fell in love with the sport.”

Amanda arrived ready to work, first measuring the battery voltage (slightly low at 12.46 volts), hooking up an OptiMate battery charger, and pulling both spark plugs with a Honda-specific CruzTOOLS kit to see for herself. The left plug presented normally except being dusky with soot. “When I saw the right spark plug, I was hopeful that it would be the only reason for the engine not turning over since they are cheap and easy to replace,” she admitted.

Next, she turned the ignition key, pushed a compression gauge into the left spark-plug hole, opened the throttle, and hit the starter button. Whir, whir, chuff, chuff, and the gauge read 155psi — a healthy number indicating the left side of the motor was likely fine. “Using the compression tester was pretty straightforward,” Amanda noted. “Having sailed with hydraulic systems and being a scuba diver, I guess measuring pressure wasn’t a novel experience. But next, when the needle didn’t even budge on the right side, I figured there was a bigger issue.”

Incidentally, having a compression gauge is a good call if you own a classic 4-stroke. But getting the right one is important, because if you work alone and your bike has only a kickstarter, imagine the fun (or rather, no fun!) of holding the gauge and working the throttle and kickstarter simultaneously. In this case, buying a screw-in gauge will help — or better yet, get two people on the job.

When 100% is bad

At this point, it wouldn’t take much mechanical skill to reason that something serious happened inside the little Honda’s right-hand cylinder. But what, exactly? Call it unrealistic optimism, but I privately hoped maybe just a spark-plug tip had come off and bent a valve, a potentially straightforward repair. But as a matter of discipline, I wanted to see what specifics could be learned before taking the engine apart.

Motion Pro’s Standard 4-Stroke Leak Down Tester provided the method. The tester meters up to 80psi of compressed air into the cylinder, with the piston located at top dead center (TDC) and both valves closed. An integrated gauge then shows the percentage of loss as air escapes. The lower the reading, the better. For instance: A 0% reading would indicate a cylinder is losing no compression through the valves, piston rings or head gasket, while a 100% reading would implicate a cylinder with a complete loss of compression due to a holed piston or broken valve. Gulp.

The leak-down tester reads 92%, an almost total loss of compression. The spark plug that came out of the right cylinder.

A couple of days later, Napper and his son Ever arrived to begin this diagnosis. With the garage air compressor delivering steady pressure to the Motion Pro tester, the left-hand reading indicated 55%, a surprisingly high number considering that the compression gauge had suggested a healthy cylinder. (Disclosure: I wasn’t able to get a perfect seal between the tester’s adapter hose and the Honda cylinder head; this allowed some air leak to escape through the spark-plug hole, raising the number.) Air could also be heard leaking from the crankcase and left-hand exhaust tip, indicating less than a perfect seal at the exhaust valve and piston rings. It was fascinating to discover that even with a good compression reading, this leak-down tester still revealed multiple pressure loss locations.

With that, Napper and his son delved into the right side of the bike. Repeating the test here proved sobering as the Motion Pro tester needle jumped to 92%, confirming essentially a total loss of compression. And with airflow now heard loudly from the crankcase and exhaust pipe, both the valve train and piston were clearly compromised. (Noise emanating from the right-hand carburetor might have revealed leakage through the intake valve too, but I failed to suggest holding the throttle open to check. My bad!)

Midway through this diagnosis, I asked Napper why he decided to invest time in a broken bike he’d already parted with, and received this thoughtful and practical answer. “I’ve always loved fixing things, as it’s incredibly rewarding to resolve that which is broken — in essence, bringing order back to that which has lost its way,” he explained. Deep!

“Also, if you’re going to own vintage machines, you better have some sense of how they work and what it takes to fix them,” he added. “If you have no clue how these machines work you’ll drive yourself crazy stumbling around in the darkness, cursing your toys because they never quite function the way they should.”

Out with the old

With the engine trauma now pinpointed, what remains is to remove the engine, and remove and rebuild the top end — at the very least. To make the job neater, cleaner and less frustrating, draining the oil made sense beforehand. For this, I employed the collegiate Derek. He’d grown up with modern dirt bikes, and found them neat and tidy in both design and maintenance ease.

In contrast to modern bikes’ steel oil drain plugs, the Honda 350 uses a giant cast-aluminum plug. It was stuck tight and its 19mm hexagonal head already had rounded corners from 47 years in service. This meant a 12-point box-end wrench lacked the working surface area necessary to loosen the plug. Instead, a six-point impact socket and a breaker bar — coupled with penetrant spray and patience — judiciously worked the plug loose. Whew. But what emerged from the sump looked like the oil gusher Jed Clampett found in the woods in The Beverly Hillbillies — “Black Gold! Texas Tea!” Even more disturbing were metal fragments found inside the hollow drain plug and a tortured aluminum chunk at the bottom of the drain pan.

“Draining the oil seemed like an intimidating task at first but turned out to be extremely easy; it did look super-dirty though, and seeing the little bits of metal was crazy!” Derek said. “Even so, not many classic bikes have caught my attention in the way the CL350 was able to — it’s absolutely gorgeous!” He also allowed the CL350 some allowances for its age, stating, “There’s no way one of these older bikes can come close to the practicality and easiness of a modern one, but classic bikes seem to have a unique charm to them — they just feel special.”

Time to rock

Ironically and inarguably, our CL350 now looks worse than it did after its initial bath. The tank and seat are off, exposing the grubby frame tubes and original wiring harness. Various engine covers removed during our diagnoses give the motor a disheveled look, and the twin horns dangle precariously, having been loosened to gain access to the right-hand exhaust tappet cover. But we’re underway.

It’s understood, these efforts represent only the first few meters in a 10k run, and what follows will be dirtier, harder, heavier, more technical, and will require more money, space and organization. And that’s mostly because pulling the engine and at least the top end are now required. And who knows if all those fasteners and gasket seals are original to 1973 — and thus firmly stuck. Let alone, what’s happened inside that fragment-strewn lower end …

At least though, due to the commitment to diagnose first — using the appropriate tools — we have a good understanding of what lies ahead, so thanks to Amanda, Derek and Napper, and to CruzTOOLS, Motion Pro and Pro Honda for getting us this far. Having never owned a Honda 350, I’m actually looking forward to the teardown and repair, and hope that it’ll be limited to a wounded piston and valves. While I know the job’s a crapshoot, I still like the odds and look forward to sharing the journey with you — including testing Honda’s first 350 Scrambler both on- and off-road — in an upcoming issue.

But I have a feeling, once the bike is repaired and running, I’m going to have to stand in line for the first ride. MC

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