Sunday, July 19, 2020

Desert Dweller comes home to roost… 1970 CB175

Rather than rescue puppies and kittens, I always seem to be drawn to the unfortunate, neglected Honda motorcycles from the 1960s-80s. Here was the text of the Craigslist posting:

There a few added photos of the extra parts that indicated that the bike was, indeed, beginning a resurrection. The “problem for me” is that the bike was located way out in the desert about 100 miles away. I asked if he ever came back into San Diego, so perhaps he could bring it closer to me and we could meet up somewhere for the purchase. The seller, Sam, came back and said he was going to have breakfast with his son in nearby Lemon Grove (5 miles away), so “no problem” to bring the bike and parts all the way to my driveway for no additional cost. SOLD!

We already had discussions about what it needed, right away, in order to get it back together again. The parts list included a right side air filter/tube, cables, sprockets and chain. So, we arranged for the transfer on 6/9/20 around 9am. Before the deal was consummated, I had already ordered $120 worth of parts to get the ball rolling as soon as possible. The first order of business will be to assess the actual needed parts that are missing or damaged, then clean the whole chassis bits. Beyond that, I have to decide what to do about the color choices. The bike is the same color/year as one that I had bought new in Puerto Rico, during my stay courtesy of the USAF in 1969-70.

Paint options include a professional job by my local paint wizard Jerry, buying a $600 used tank from the UK or doing a rattle can job in some other color just to get by for now. The frame is black, so hopefully can be cleaned and touched up with gloss black paint, but the side covers and fuel tank will need something special to set it off from the normal paint schemes, I think.

The next day….

Well, the first thing in the morning, before the bike arrived, I realized that I had made a big mistake on ordering the air filter parts that were mentioned as missing. Despite the seemingly identical appearance between a 1969 and a 1970 CB175, there ARE differences in a lot of small items, including the whole air filter system! The 1969 bikes have a small, uncovered filter with a separate air filter connector tube. The 1970 models have a different filter system that includes plastic covers to enshroud the whole filter assembly leaving an air intake port high in the outer cover. The air filters have an integral connector tube, as well. The bike turned out to have a 12/69 build date, putting it squarely in the 1970 production run, not the “as-advertised” 1969 model year stated.

Other changes were the shape and design of the outer side covers, rear shock covers, seat cover pattern, rear sprocket, fork covers and minor changes in the paint scheme. The main product code for the 1969 is 306, but the 1970 looks like it has 315 coded parts added on. According to the parts list, the top fork bolts are 273 code from the CL72!

So, what could go wrong…?
1. The supplied rear tire is a 3.50x18, so too big for the bike.
2. The supplied left air filter is a 351 code for CB200T, not a 315 CB175K4 code part.
3. The forks were stuck in the steering stem, but finally worked loose. When dismantled for a fork seal change, there was very little fork oil left in the forks, replaced by moisture which caused the fork bushing and rebound valve to be firmly rusted in place. Used fork set was ordered from eBay.
4. Both handlebar controls were damaged and unusable. $120 for a pair.
5. Headlight shell was cracked around the edge (brittle plastic) and replacements are in the $150-250 range. Found used for $60
6. Air filters are $75-85 each side, when you can find them. DSS to the rescue. $150 a set
7. The left side carburetor slide was MIA, so a used replacement was found for $30. A few weeks later the seller found the slide hidden beneath his Harley...
8. All of the side cover grommets, instrument cushions and fork cushions needed to be replaced.
9. The rear brake shoes were worn down, requiring replacement.
10. The bike had the chain come off the sprockets at some point, damaging the sprocket mounting bolts and nuts, plus wore a groove in the rear shock body. Replaced all the hardware and front sprocket.
11. The front sprocket required use of a 3-jaw puller to remove from the rusted shaft.
12. All the cables were fried due to heat and age, which was visible and expected.
13. Someone had tried to replace the point set with something from a different model or manufacturer, so they re-drilled screw holes in the point plate to get the points to mount up and function. $30 for used parts
14. Coil leads were stiff and broken, so a replacement coil was ordered. $30
15. The centerstand leg on the left side was bent forward and there was a big ugly weld on the foot. Heated up with a MAPP gas torch and straightened out somewhat.
16. Pinholes in the top of the front of the gas tank! REDCOAT sealer used, but failed to seal up the pinholes.

I repacked the steering head bearings and slowly cleaned/painted the frame, as I went from front to back. Finally, I realized that the best thing to do is to remove the engine from the frame and finish cleaning it up, plus get the engine down on the ground for a major descaling and cleaning job.

With the engine out, I noticed signs of water in the right side intake port, so the cylinder head was removed to find some water damage in the cylinder and piston. It was still on STD bore, so it seemed reasonable to just have it bored out to .5mm oversize and have a fresh set of cylinders to work with. The camchain tensioner rollers were hard and pitted, so those needed replacement, as well.

A set of .50 pistons/rings and a bore job cost $160. The valves/seats were still in decent shape, so were cleaned and reinstalled with new stem seals on the exhaust sides. You could tell that the engine had been out for some reason before, as there were non-OEM nuts and bolts holding the engine into the frame. I pulled the clutch cover to get a quick view of the inside of the engine and found only 3 of the 4 required clutch spring bolts in place.

With the engine out and top cover off the camshaft and rockers looked dry, but not damaged, fortunately. The camchain tensioner rollers were worn out, so a good used tensioner was found on eBay along with a new center roller. I had to wait an extra 5 days for the correct center roller after the seller sent a mystery roller from his bag of three that wasn’t even close to fitting.

I sprung for the whole master carb kit from which included floats and various sizes of jets for idle and main jet calibration. For some reason, the left carburetor would not fill properly until the old parts were reinstalled.

New handlebar switches came from and my friends in Thailand, who supplied a new clutch adjuster. With 16k miles showing on the odometer, you expect to find worn parts here and there like the clutch adjuster. All new cables from were shipped at a reasonable cost, but there were some issues with the clutch cable end not fitting back into the clutch joint and the front brake cable fitting was 1mm too large for the backing plate. The throttle cable junction was made up of plastic and big molded rubber parts that got trapped between the tank and frame. 4into1 acknowledged some of the issues with their supplier and eventually refunded me the cost of the cable set.

The fork covers were all trashed from crashes, so I ordered up some various ones from DSS. The fork ears come in several variations of how the turn signals mount and where the reflector mounts. Most of them were very inexpensive so I bought a number of them just to see if I could put together something a little different than the original setup. DSS supplied most of the rubber grommets for the frame side covers and instrument mounts. The speedo and tach instrument light sockets are rubber coated and were baked into the meter housing openings. Once removed, the little indicator jewels fell apart from age and heat. Ultimately, the meters did operate correctly, so the other issues were left as-is.

There was LOTS of cleaning of the desert dust and corrosion. Most all of the chrome parts were pitted and caked with dirt/dust. I rattle-canned the frame with black Duplicolor engine paint, as I went along. This was destined to be a daily driver not a showpiece, so a whole teardown/powdercoat of the chassis was not in the budget, which still got blown up in the end. Even with generous discounts from my suppliers and careful eBay shopping, the parts bill ran up past $1200 quickly. My labor time was beyond 30 hours, but when you are in quarantine, what else is there to do, anyway?

When all the components were finally assembled, the bike fired up using a spare CL175K0 fuel tank that was given to me by my friend Ron Smith. I had soaked it for a few days with white vinegar to help clean out the insides, but it turned out to be inefficient as newly introduced fuel seemed to dissolve leftover fuel deposits which contaminated the petcock and carburetors. The original fuel tank had been coated with REDCOAT tank sealer, but it didn’t find its way all the way up towards the pinholes in the front of the tank. Even so, with a couple of gallons of gas, the bike was fired up safely and then developed more problems. There was smoke coming from the left side muffler and what sounded like camchain noises coming out of the engine… Gads!

I pulled the engine again, removed the top end to check for broken rings and possible causes of the camchain noises, but found nothing out of the ordinary. The intake ports in the head had gathered up a lot of unburned deposits, which apparently were being slowly sucked into the engine, causing plug fouling and smoke. A big shot of brake cleaner purged the intake ports and the engine was reassembled again. The aftermarket gasket kit was not very accurately made and the thin, non-asbestos paper that the kit was made from was pretty much a single-use product. The clutch cover gasket was cleaned and coated with Gasket-Cinch to help seal up the weeping on that side and the simple round 3 hole gasket for the dyno cover continues to leak oil for no apparent reason. The aftermarket gasket thickness is thinner than original OEM gasket materials.

After reinstalling the engine and taming the carburetor feed issues, the engine fired back up sounding much healthier and without smoking. The plugs came out tan-colored, instead of black and oily, finally. There is still a bit of an air leak or some kind of issue with the left side carburetor at idle, but the engine pulls with good power off-idle and beyond.

I’ve lined up a good used rear luggage rack for the bike and it will wind up being my mule to haul stuff back and forth the PO a couple of miles away. That was the original intent, anyway until I went out and bought a new Royal Enfield Interceptor 650!

Well, it lives again, but needs a good paint job unless a new buyer likes the “rat bike” look. The bike has made several post office trips and seems to be running normally, so far. May need to make a few more jetting adjustments, but otherwise, it is what it is… a 50-year-old Honda CB175.

Bill “MrHonda” Silver

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