Monday, May 27, 2019

A most unusual Honda CB400F… Part 2


There is a whole separate story about the poor shipper who bid on the bike’s shipping costs and got waylaid during his trip, but I will cut to the chase and evaluate what showed up at my residence a week or so later.

The bike was dirty, oily and smelled of gasoline when it arrived. The rims had rust, spokes were dull, the rear brake backing plate was devoid of its factory finish, both fork seals started bleeding oil after arrival and the battery was held in with a bit of copper wire, plus lacked the requisite battery vent tube. Lacking the vent tube, battery acids flew backwards, beneath the bodywork, spraying sulfuric acid on the frame tubing and the rectifier, which is bolted to the frame on that side. The drive chain was dirty and rusty and there were unsightly blemishes in the black paint where apparently a tarp was laid across the bodywork for a few generations.  The master cylinder was drooling a bit of brake fluid and the caliper proved to be packed with decades-old muck, requiring replacement of the seal ring, piston and brake pads. The fuel tank was seeping fuel out of a lengthwise crack that had been unsuccessfully repaired with a layer of fiberglass cloth and resin.  The leak drooled gasoline all over the cylinder head and much of the upper end of the bike, which mixed with old dirt, oil and other contaminants.

It appeared that the engine might have been removed before it was painted satin black, as there wasn’t any noticeable overspray to be seen on the frame mounts. Whatever it was, after 40 years, the paint was no longer staying adhered to the engine components. I was tempted to call the bike “Calico” due to the blotchy spots of paint that remained all over the engine.

Apparently, the Tracy bodywork installation required removal of the side cover anchor bracket on the left side and removal of both of the welded-on seat brackets. Perhaps the mislabeled bike title “1975 CB450” was a clue as to the actual ownership knowledge of the machine. The fuel tank had some kind of silver coating, which was disintegrating rapidly. The petcock appeared to be an aftermarket copy of a dual outlet CB750 SOHC unit, but only one fitting can be used on the single feed CB400F carb sets. An interesting side note is that the big rectangular tail light lens has Suzuki on the edge and appears to be from an early 1980s GS850 or similar model. I finally got the key (copy) in the mail with the title, but the bike only turned over a few times before the battery went dead. It showed 11.75 volts on the bench before connecting the charger to the terminals.  A day later it was showing 13.25 volts, so there was some hope for it.

In the meantime, the 1-piece bodywork was wrestled off the chassis and rolled over to expose some ugly fiberglass work done on the bottom, probably to address fuel leaks there. The tail light wiring was held together with wire nuts and the two bodywork mounting bolts at the rear frame had no nuts attached.

As mentioned previously, the engine had been painted satin black, perhaps 40 years ago, but the paint was peeling off in many areas. The carburetors were fitted with K&N pod filters, instead of the factory air box. There was old gasoline and oil residue all over the top of the engine as well as underneath.

I decided to just pull the carburetors off and disassemble them for cleaning and to see what jetting sizes had been installed. All four carburetor throttle bodies were coated in a brown, slimy coating on the insides, leading to the intake manifolds and inlet ports on the cylinder head.  The intake manifolds appeared to be originals, so new replacements were ordered, along with new carb kits, brake parts, fork seals, spoke kits, a battery strap, spark plugs, tune-up parts and lots more, which ran up a $300 bill at

A lengthy carb strip, cleaning and installation of new o-rings brought the carbs back up to spec and the bike started up and ran cleanly, initially... I was pleased to see that the jets installed were #40 idle jets and #80 main jets. Stock jetting is #40 and #75, so obviously the bike needed extra fueling to compensate for the 4:1 Kerker exhaust and the lack of a proper air box/filter for the intake side. Additional main jet increases may be required due to the CA alcohol infused fuels, which is the only option these days in California. The carb rack is nearly identical to the one used on the CB350F predecessor, which are calibrated with #35 and #75 jetting.

On subsequent restarts the engine would only run on 3 cylinders, leaving #4 with a cold exhaust pipe. The carb rack was removed again and a tiny piece of fluff was found to have gotten into the #4 cylinder’s pilot jet. With carbs reinstalled, the engine fired up sounding healthy once again. While checking for other #4 cylinder possible problem areas, a test of the plug caps found that all of them had between 9k and 10k ohm resistance readings, so they were all replaced with new NGK 5k ohm caps. 

The engine now sounds good with no unusual tapping, clicking or banging around inside. An oil cooler had been fitted to the bike, but 40 year-old oil lines were dripping at the connections. New hoses, oil and filter helped to clean things up, inside and out.

An additional $250 was spent on new tires, tubes and rim bands. The 4.10x18 (replaces 3.50x18) sized tires were mounted on both wheels, which were over-sized for the rim width up front and were probably 40 years old. The bike got a good bath to degrease and clean the engine and chassis, while a fresh batch of Caswell tank sealer was ordered to help remedy the failing fuel tank cavity.
Removing the points cover revealed OEM Honda points and condensers in place. Once the engine has been evaluated for reliability, perhaps a Dyna ignition will be installed.  Compression readings ran right around 170 psi on all cylinders, which is right at OEM specifications.

The bike did come with some takeoff parts, including a poorly repainted stock fuel tank (with dent), a stock seat, one repainted side cover, the OEM rear outer fender (also painted yellow) and tail light assembly, plus the matching Tracy quarter fairing, which had not been installed on the bike. The fuel tank had an aftermarket keyed gas cap latch, which was missing the key portion. A screwdriver was used to open the latch and mercifully the fuel tank was shiny and clean inside. The OEM petcock was with the tank and a good usable part. The seat was original, but starting to split along the heat stamped seams, so would need a new cover, but can’t be used on this chassis due to lack of brackets.

I have to say that I failed to do my “due diligence” before the purchase in getting more detailed photos, asking more pertinent questions and working out the paperwork details. In hindsight, it wasn’t the best purchase I have ever made, despite being a hard to find CB400F with the one-of-three (reportedly) Tracy bodywork. The photos of the bike didn’t reveal the paint discoloration, leaking forks (which is an automatic with these bikes for some reason) and other details. Still, it had “good bones” but was probably over-priced for the condition that it was in.

Wrestling a 4.5 foot long hunk of fiberglass became taxing in a hurry. In order to seal the fuel tank, an order of Caswell epoxy sealer was made and received. They recommended using a quick splash of acetone or good old Dawn dishwasher detergent and lots of water to flush. The difficulty with the Dawn rinse was getting the tank dried out again afterwards. Plus there was quite a bit of the old thick sealer bits floating around inside which needed to be extracted mostly by shaking the whole assembly upside down. The whole thing is quite unwieldy to say the least, but after a few rounds of compressed air and a heat gun, it seemed to be ready to seal up with the Caswell product. 

The petcock had been removed and the holes sealed with a couple of 6mm screws and a rubber plug for the center hole. A plastic storage bag was employed to seal up a spare gas cap, when the tank was inverted to seal up the top surfaces. After mixing the sealant cans and pouring them down inside the tank, the cap was installed and the whole unit turned in all possible axis and angles in order to fully coat the rough interior of the tank chamber.  Surprisingly, once the gyrations were completed, virtually no excess sealer drained out of the tank openings. I’m not sure about the actual capacity of the fuel tank chamber, but it appears to be more extended than first realized. The bumpy internal surfaces seemed to have absorbed the fuel tank sealer, due to excessive surface area than would be found inside a steel fuel tank.

The tank cured in the SoCal sun for 2 days, hardening to a fuel-proof (I hope) glaze. Before remounting the Tracy bodywork, more repairs were made, including trying to piece together the original airbox and air filter assemblies, which were gutted because of the installation of the K&N pod filters. There are numerous pieces to replace in the air box assembly, which is mostly a carryover from the parent CB350F model.  A few of the pieces have been reproduced, but building up a system from scratch could run up into the $300 range. I slowly picked up bits and pieces from eBay sellers and my friends at 4:1 in SFO to resurrect the OEM air filter system trying to keep the cost down around $100, but I had to pay $50 just for the air box lid.

As an alternate to the Tracy bodywork option, a roundup of OEM headlight components was initiated to replace the massive H4 unit installed upon rather crudely-welded and modified headlight mount.  Again, an eBay seller came up with a whole front bracket and turn signal light assembly at a fraction of the “new price” or even some of the used parts on the market.
The inner rear fender liner was missing, so another check of eBay found a decent one for sale at a good price. The rear mounting holes are fitted with 6mm sized bolt holes which are a good bit smaller than the big holes drilled for the Tracy bodywork setup. A couple of fender washers will help take up the hole size in the rear frame crossover bracket and should clamp the whole assembly down securely.

The rest of the chassis was treated to new front fork seals and dust boots and the 13.25” Koni shocks replaced with a supplied set of vintage Mulholland branded shocks of the correct 12.5” lengths. Both wheels were stripped apart, cleaned and re-spoked with kits from Marty at the site. The front brake caliper was cleaned out with a new piston and seal ring installed. New pads completed the front brake repairs, but the master cylinder remains to be rebuilt.

The engine was first degreased then a spray-on, citrus based, paint stripper used on the leftover black paint splotches. For the most part, the 1-2 punch cleaned and removed much of the black paint, but there are still little nooks and crannies where the spray didn’t reach effectively.

Small stopper brackets were made to prevent the centerstand from hitting the drive chain in the retracted position. The usual stopper for the stand rests against the OEM muffler, which is no longer present.

New wiring leads were made for the sub-harness coming back from the rear bodywork section which feeds the tail light and turn signals. It isn’t clear as to whether the rear signal units are still available and of a kind which will mount up to the OEM Honda headlight mount and signal stalks.
After paying DMV handsomely for current registration and tags, the bike was ready for a short test run, finally! With a 16t front sprocket, the acceleration was brisk and the engine ran cleanly all the way up to redline in lower gears. The rear shocks/springs, which date back almost as old as the whole bike, seemed to have decent spring rate and damping, but these chassis are still 40+ years old and lack refinement to match even the cheapest of today’s street machines.

Surprisingly, the Kerker exhaust is relatively well muffled, but still gives off a distinctive sound when the revs come up to 5 figures. With a 458cc kit and a hotter camshaft, the whole package would be more in keeping with the futuristic body styling. The handlebars are stock OEM first generation low riser types, so the whole riding setup is café style, but not unbearable for us older folks.

To date, a week after the fuel tank sealing adventure, there is no sign of gasoline leaking from the tank. The petcock location is somewhat unfortunate, in that the petcock fuel fitting location puts the fuel line up next to the carburetor body. The whole bodywork package precludes use of the tool tray, which normally sits atop the air filter housing, so the practicality of this bodywork option is lacking in that regard.

Hopefully, the tainted paint work might rub out with compound and a good wax job. The whole bike is a bit above “rat bike” status, cosmetically, but it seems to be solid mechanically and is fun to ride, so far. It will either be the bike that I take to my grave or perhaps someone will feel the need to take over a restoration project like this and wind up with one very unique CB400F.

Bill “MrHonda” Silver

No comments:

Post a Comment