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Honda 350 Imposters revealed… how things are not always what they seem

Restored in the 1970s, the bike was built with a WEBCO 350cc kit and roller rocker camshaft kit.
Restored in the 1970s, the bike was built with a WEBCO 350cc kit and roller rocker camshaft kit.
Bill Silver

In the last few days, a couple of vintage Hondas showed up in the driveway, one a newcomer to my stable and one a return visitor after a tough couple of years. One doesn’t look like a Honda 350 and the other one looks like one, but isn’t!

What appears to be a 1965 Honda CB77 Super Hawk is, if the story is correct, an actual WEBCO 350cc kitted bike with a H-C roller rocker camshaft kit installed, as well. The bike was reportedly built in the 1970s, back when some of these parts were still in active circulation. I had the WEBCO 350cc kit instructions as a part of my CB/CL72-77 Restoration Guide CD package, but was missing the Harmon-Collins roller cam instruction sheets until now. The bike came with a binder with some photocopies of the parts books, the WEBCO installation instructions and an original H-C roller cam instruction page.

The camshaft timing ticket shows this camshaft to be 7236 MK1 model with 50/84 and 42/90 inlet/exhaust - open/closing events, with .346/.316” valve lift. A quick look at the left side exhaust valve tappet cover revealed a stout-looking rocker arm and a bright and shiny alloy valve retainer, which is consistent with the roller camshaft installation. Setting up this engine configuration is time-consuming and detailed, so one would hope that the job was done right the first time.

My expectations were lowered abruptly when I removed the point cover on the right side of the cylinder head. The whole ignition plate was installed UPSIDE DOWN, which only means ONE THING; the point cam was installed 180 degrees out of phase and they didn’t notice it until the motor was put into the chassis. The only workaround is installing the point plate inverted to put the points back in phase with the camshaft timing. STRIKE ONE!

I quick look inside the float bowl revealed OLD gas lying in the bottom and the floats were hitting the edges of the float bowl gasket, preventing the float from traveling fully upwards to close the float valve. STRIKE TWO! On the tentative “plus-side,” the main jets were #145s, as called for by the instruction sheets.

The bike had NOS OEM 1 piece -670 muffler systems installed, however both header pipes were slightly discolored already. Normally-tuned CB77s won’t turn the header pipes blue/yellow unless they are not setup properly and then either left to idle too long or left with the choke ON too long. Incorrect ignition timing will also start an errant heat cycle, causing pipe discoloration, as well. STRIKE THREE!

In reviewing the overall build of the bike, I was dismayed to find that the suggested additional oiling modification for the cylinders was NOT performed. This oiling mod is created by drilling from the front of the cylinder block oil feed passage directly into the forward edge of the cylinder liner. The outer screw hole is then threaded and tapped for a small pipe plug.

The bike came without a battery, but the previous owner said that he had fired the bike up just after he purchased it a few years back, so the first order of business was to order a new, correct 12N9-3A battery. Apparently, this bike has not really been driven much, if at all. There is still the factory grease on the drive chain and the ribbed front tire is an OEM Bridgestone item, dating from WAY BACK WHEN.

According to the cam specifications tag, the valve clearances are to be set at .007” vs. .004” for a stock Super Hawk motor. I will verify these clearances prior to any attempt at starting the engine, with a prayer that the rest of the installation was done with some accuracy.

To be continued…

Meanwhile, I received a call from my friend Lisa, who owns “Rhonda the Honda,” a 1974 CB350F, which has been café-racered out a little bit, but is getting long in the tooth now. Lisa was hit nearly head-on with some errant cage driver, causing her to suffer a broken forearm and damaged hand injuries. This was two and a half years ago! She is just now getting some kind of settlement from the insurance companies involved, as the car drive was under-insured at the time of the collision.

The bike took a frontal hit, bending the wheel, forks, plus smashing the headlight and front fender. Lisa had it towed to a local vintage repair shop who did an estimate on it, then let it sit for months on end, while repair funds could be procured. Eventually, it was put back on its feet with mostly used parts from salvage yards and eBay sellers. Lisa wasn’t really able to drive the bike very much, so it went into long-term storage with old gas in the fuel system and a failing brake system. Lisa mentioned having to whack the caliper with a mallet every so often when the front brake would seize up. Finally, she had enough and parked it. Last week, the cry for help came via email and delivery was arranged a few days ago.

The brake system had just a bit of brake fluid left in the bottom of the reservoir, but little signs of fluid leakage around the brake lever, which is where they usually leak. I filled the little fluid cup and then went down to the brake caliper for a look. After removing the two large through-bolts, the caliper parted and it became evident that the brake fluid loss was down there, not up at the top. I dimly recalled doing a caliper clean on the bike, some years ago and surmised that the caliper piston was now deeply pitted causing the fluid leaks.

Using the master cylinder for fluid pressure, I was able to pump out the stuck brake pad, then the caliper piston followed shortly thereafter. Ker-plunk into the plastic drain pan it went! It didn’t take much of a close look to see that the piston was riddled with termite-looking pits, all around the circumference of the piston surface. Time to ring up my buddy, Marty Mattern, owner of a website business dedicated to providing vintage Honda owners with a lot of the hardware and system parts to rebuild 40-50 year old Honda models.

Thankfully, someone has created formed float bowl gaskets for the 350-400F carburetors and he was about to get a new shipment in within a day or so. He also had the rest of the brake parts, including reproduction caliper bodies and pistons. An order has been placed and parts should arrive within a few days. In the meantime, the next step was to remove the carburetors for inspection and cleaning. Having owned many 350-400F bikes in the past, I can have the carbs off in about 10 minutes or less. They reeked of stale gasoline, but once the bowls were off, the jets all looked pretty good, but something was missing! All of the spring clips that hold the main jets in place were gone! Apparently, Honda no longer makes these available under the 16061-323-004 part number (CB500 Four source), so some enterprising company in AZ has begun to reproduce them at $45 a set.

The biggest issue with the carbs, beyond that, is that there were a lot of fine rust particles in the bottom of the float bowls. Opening the gas cap revealed a lot of rust buildup inside fuel tank, as it was not left filled-up when it went into storage. The air space above the fuel level condensed during hot/cold cycles of the last year and the moisture attacked the insides of the fuel tank surfaces. Dealing with rusty fuel tanks is not high on my list of favorite tasks in motorcycle repair, so I will have to drain what’s in there and see just how bad things might really be.

So, why do I call this bike an imposter? When the head gasket started leaking, a few years back, I ordered a CB350F top end gasket set to make the repairs. Imagine my shock when the head gasket didn’t fit the cylinder block! I rechecked the engine serial numbers and discovered that they started with CB400F…

Stay tuned for the next installment...

Bill "MrHonda" Silver

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