1975 CB125S refurb

spurlock

New Member
We've had a string of rainy days here so I've been holed up in my shop finishing up some final details on my '75 CB125S and thought I would share what I've done with it and my experiences with parts suppliers. When I bought the bike 6 months and 1,800 miles ago it had only 3,140 well cared for miles on it so it was in exceptional condition for its age. So I've just been taking it to the next level. It's been really satisfying to me as I get back in touch with my Honda shop wrenching days from 1965 to 1980.

The main mechanical work has been replacement of a few seals and O rings to stop minor oil seepage, replacement of wheel bearings and steering stem bearings, a bit of electrical maintenance and modifying the rear shocks to make damping adjustment possible. But most of the work has been cosmetic: cleaning, buffing, and painting. For the most part I have tried to maintain originality. Exceptions are the rear shock modification (which I consider an essential safety issue), retaining the lower-than-stock handlebars which came on the bike, going up one tooth on the countershaft sprocket, and polishing some parts that were not originally polished. So here goes some pictures and comments.
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This little bike is amazingly fun and capable. I only weigh 140# so it cruises comfortably at 45 - 55 and easily pulls away from 30 mph in 5th gear. I started attacking the most glaring cosmetic problems first, but as I worked around the bike and the overall look improved I found myself going back and refining bits that looked "good enough" the first time around. For original Honda parts I've used several online dealers but have found Service Honda to have better prices in many cases. Anyone have other suggestions for a best go-to source of still available original parts? For discontinued NOS parts I've had good luck using several ebay vendors in Thailand. But many ebay ads clearly have incorrect part descriptions so it's obviously buyer beware time.

Cracked side covers
When I bought it its worst flaw was cracked plastic side covers. Of course originals are unavailable so I ordered aftermarket copies from Thailand on ebay. They were economical even with shipping, but were white so I bit the bullet and ordered the silver base, candy riviera blue, and clear top coat from VMR Paints ($140 for three rattle cans). I found the paints very well behaved, the color match is perfect, and the catalyzed clear coat seems very hard.
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Handlebars
The non-stock low bars felt great but just a bit too wide for such a small bike, so I sawed 2" off each end and shortened the cables to match.
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Engine cleaning
The engine was quite clean but I scrubbed it with household cleaner and a bristle brush to get between the fins. Really brightened up the aluminum. I also used a Scotchbrite pad to brighten up the outer edges of the fins.
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Engine polishing/painting
I buffed and clear coated the points and alternator covers, tappet caps, and oil filter screen cap, then repainted the silver painted case covers since the original paint was dulled. I used DupliColor DE1636 Clear and for the silver parts DE1615 Aluminum. I've read that the DupliColor silver caliper paint is maybe the best match for the original Honda Cloud Silver, but have not found it locally. The frame steering neck, down tube and lower front engine bracket were dinged from road rocks so I used Krylon Black Gloss on them. The Dupli-Color DA1600 Gloss Black seems to be more of a grey black whereas the Krylon black seems more of a blue-black like the original. What have others used for Honda black parts?
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The clutch cover also got new silver paint, and as I had any screws, brackets etc. off I buffed them. New 6mm nuts from the local hardware store are just about an exact match for the originals, so rather than buffing old nuts I replaced them, like the clutch adj. nut at the bottom of this case.
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Spokes
The original spokes were not rusty but had their typical tarnish. Originals are unavailable so I gambled and lost on Thailand aftermarket spokes. Next time I will go with Buchanan. After disassembling the front wheel I found the Thailand spokes were a bit too long, the nipples not a good fit for the dimples in the rims, the spokes too fat to slide easily into the hub, and the heads at the hub bends too big to sit in the hub recesses. So I went to plan B and buffed each spoke and nipple individually. The original plating is not perfect and never was great, but the end result is real nice. While apart I buffed the outer hub flanges and glass bed blasted the hub centers, then clear coated. I waxed the buffed spokes with paste wax and laced 'em back up. Oh, and replaced the wheel bearings while I was at it.
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The rear hub got the same treatment. Notice the spoke balance weights - after lacing the wheels I static balanced them. You might not think that important for a little low speed bike, but I like to do it and feel it contributes to a smooth ride. It can be revealing to put the bike on the center stand and run it up to cruising speed in top gear. Before balancing, the wheel and swing arm would hop up and down, and afterwards it spins turbine smooth.
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Steering stem
The steering stem bearings had a very slight tendency to self center as though the races were worn. It may have just been old stiff grease, but the parts were cheap and available so I replaced them. Plus the stem had some rust so this was a chance to paint it and the steering neck area of the frame.
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Fork crown, cable cleaning
The original fork crown anodizing was worn and faded so I painted it and the bar clamps with Dupli-Color 1608 Semi-Gloss Black. More shiny than original but I like it. I also cleaned up the darkening of the cables using acetone and a scotchbrite pad. The split photo below shows the brake cable before and after.
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Kick stands
The center stand, side stand and footpeg bar also got repainted with semi gloss, with springs and all fasteners buffed.
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Front disc brake
The mechanical front brake caliper got a work over including the semi-gloss paint, hardware polish, and brake pad replacement to correct a grease contaminated pad. I found the replacement aftermarket pads on ebay from a vendor in Canada. These mechanical brakes are weaklings compared to hydraulics, but better than the puny drums used on earlier and later 125 models. One quirk is that as the brake is applied and the front end dives, the loop at the top of the cable bends sharper which makes the inner cable effectively shorter than the outer. This adds more braking force, sort of like a power brake booster. Handy on smooth ground but a bit odd when braking over bumps as the braking force changes slightly with each bump. The forks got an oil change and flush, and the fork lowers got a stripping, buffing and clear coating also.
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Soon afterwards the brake developed squeaking problems so I tried the usual magic greases and squeak stop compounds, beveling the edges of the pads, etc. but the squeaks always came back. Two last modifications seem to have solved the problem. First I added a very thin rubber impregnated cloth disc (cut from player piano bellows material) behind the stationary pad. Second, I found that the caliper always wanted to ride lightly against the inboard side of the disc, apparently due to the stiffness of the cable. So I added the spring wire visible below (from the fender bolt and bearing against the outer caliper) and carefully adjusted it until neither pad drags on the disc. So far so good.
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Pitted chrome
All the chrome parts on the bike are original and look great from 5' away, but closeup in good light they show their age. The original chrome on these little bikes was really rough and thin at best, and 39 years have taken their toll. The bike would never show well in sunlight. Not that I plan to display it in shows since I love to ride it so much. But it is surprising how nice it looks from a distance when up close the original crude factory grinding marks and subsequent rust marks stand out.
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Hardware
I have buffed and clear coated most of the bolts and parts that were originally zinc plated, like this passenger peg. Even though it makes them more shiny than original, they were not bad enough to warrant replating and this way I can arrest further corrosion.
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Though I've buffed several parts that were originally dull I draw the line at buffing the carburetor - I always thought a highly polished carb looked tacky. So I just gave it a good ultrasonic cleaning. The exposed brass parts got rubbed with a scotchbright pad and clear coated. The coil wire clip was rusty so I glass bead blasted it and the carb spacer and clear coated them as well. The original rubber air filter to carb tube was cracked so I replaced with a NOS one from an ebay vendor in Thailand.
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Magnetic drain plug
I'm a believer in magnetic drain plugs, especially for engines without paper oil filters. There will still be clutch and aluminum particles floating around in the oil unless the centrifugal filter gets them. But I like getting steel out of the system upstream from the oil pump intake. Magnetic plugs are also a good way to monitor for possible engine problems. If there is suddenly an increase in metal fuzz on the magnet during oil change, it's time to look for a problem, often a ball bearing crapping out. So I routinely drill drain plugs for 1/4" x 1/2" rare earth magnets and epoxy the magnets in place. Can't hurt, might help. Opinions?
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Electrical/ignition service
The electrics were in great shape, it had a brand new battery and rectifier and some new bulbs so I suspect the bike was run with the original battery badly sulfated so the charging system fried a few things. So just for reliability I made sure all connections were clean and tight. Also, since the system is only 6 volt and it needs every volt it has I checked for voltage drops through all switches. With the key on and the engine running, a voltmeter spanning the two key switch terminals showed a 0.15 volt drop. After disassembling, cleaning and lubricating the internal switch contacts the drop was less than .05 volts. So I then did the same treatment to all the handlebar switches. And to maximize ignition power I did a few things: first set the points gap to the minimum .3mm figuring that the longer they are closed (maximum dwell) the more time the coil will have to get fully charged. Next I checked voltage drop across the handlebar on/off switch and was surprised to find a 0.1 volt drop. So I bypassed the (useless, never needed) kill switch and eliminated that small loss. Finally I replaced the original 20K ohm resister spark plug cap with an NGK non-resistor cap from my Honda rototiller.

Ongoing maintenance
I love this little bike and want it to last as long as possible so I'm changing the oil every 300 miles, after all it is only 1 quart and inspecting the magnetic drain plugs is a good way to monitor for problems. I plan to change fork oil every year. The fork seals appear original and there are no leaks so I think it's worth extra effort to maximize seal and bushing life. Other than that it is just routine adjustments and lubrication, avoiding rain and sun, and most importantly riding fun twisty roads.

Again I don't pretend that my refurbishing compares to the complete and total restorations that happen out there, but I find it really satisfying to have reversed the aging of this vintage bike and am loving riding it. I can't stop in a parking lot without getting offers to buy it or comments of "wow, that is a beautiful bike, what year is that?"
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-Bill
 
Nice bike.................wish mine looked half that.

1/4 that.......................
 
Gotta say Bill, 5 posts into this forum and you're already earning a great deal of respect from a number of members whose respect is remarkably difficult to earn. Job well done sir, that CB looks clean enough to eat off of!
 
This baby is too clean!! You really went the extra mile with every step. I wish I could get my hands on some candy riviera paint... I opted to just Frankenstein my broken side cover together.

The magnetic oil plug is a good idea. Any fear that it might come loose?

Also, this should help explain posting pictures with bbcode http://www.wikihow.com/Upload-Images-in-BBCode
 
maxDTM said:
The magnetic oil plug is a good idea. Any fear that it might come loose?

Also, this should help explain posting pictures with bbcode http://www.wikihow.com/Upload-Images-in-BBCode

Thanks for the image posting info, I will try embedding direct image code. It is so much easier to explain something when you can alternate text with pictures.

I'm not worried about the magnets coming loose, maybe I should be but have done this for about 40 years on all kinds of engines. I use a good quality stiff epoxy made for bonding parts, usually that will be black or dark grey and have high density filler as a stiffener. But I do bead blast the end that will be epoxied to rough it up, or grinding a notch in one end would lock it in place as well. And of course first make sure that it does not protrude into the case far enough to touch any moving parts!

-Bill
 
Back in the day, I had a RD200 and my brother had a cb125s ....
although I cafe'd the arse out of my RD, I loved riding the bog standard CB, and it would go to the moon and back on a tank of petrol.
 
grcamna5 said:
spurlock,
Tell/show us the mods you made to the rear shocks for damping adjustment.

Here's my original post on the VJMOG forum. It has a couple of photos and a link to a photobucket album with more pics::
http://www.vjmog.com/ftopict-10455-modify.html+rear+shocks+allow+damping

-Bill
 
Bill,
Great looking 'Gem' of a 75' CB125S you have there ! 8)
I purchased an 81' CB125S that sat outside for over 25 yrs. Very rusty.. I did PC and it'll get a full 'frankenMod' complete w/ pumped up XR200 engine;I won't be making it 'Sparkly' ;) 8) like yours because I live in a low rent apt. and it'll spend much time parked outside in all kinds of weather/parking situations,etc. it'll be 90% of my full time everyday transportation complete w/ rack.
I love stock better though.. :D
Thanks for the link for your rear shock mods.
 

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bump,I'll be doing this rear shock 're-hab'/oil change to a pr. of oem Suzuki TS185 rear shocks to install on my CB125,I hope I get the viscosity of the damper oil correct. :)
They're only a 1/4" longer eye-eye than my oem stock CB125S shocks but have much better 'feel' to the damping :)
 

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Great work! Very clean. It's the details that matter!

Sounds like you pretty much used different types of Dupli-color DE for each part to get it back to looking like new.
I'm new to restoring and was wondering what the best method of getting the bike looking like new is. Any other tips?


Sent from my iPhone using DO THE TON
 
thefish said:
. . . I'm new to restoring and was wondering what the best method of getting the bike looking like new is. Any other tips?
Sent from my iPhone using DO THE TON

Well, depends on what shape it is in. But in general you need lots of elbow grease, a good buffing wheel, knowledge of paints and pre-painting surface prep, and usually some type of blasting cabinet comes in handy. Glass bead blasting is useful for cleaning/prepping surfaces to be painted, and soda blasting does a great job on bare aluminum cooling fins and other parts whre you con't want to remove any material. Oh, and did I mention lots of elbow grease?

Here are before and after shots of an engine and carbs on a CB400F I did. The head cover and crankcase covers were stripped and painted the original silver, then clear coated. The cylinder and head were just soda blasted and left unpainted as original.

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The alternator case was scarred and its cover plate chewed up.
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I repaired the case with epoxy and bought a new cover plate.
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Hope this helps,

-Bill
 
That came out nice 8) I like the job the soda blaster did on the fins,etc.Those CB400F's are always stained from the weeping head gaskets and tough to get between the fins;did you paint the cylinder/head fins also ?
 
grcamna5 said:
That came out nice 8) I like the job the soda blaster did on the fins,etc.Those CB400F's are always stained from the weeping head gaskets and tough to get between the fins;did you paint the cylinder/head fins also ?

Thanks. I went ahead and posted a full build thread on that bike here if anyone is interested: http://www.dotheton.com/forum/index.php?topic=72261.new#new

I left the cylinder and head unpainted raw aluminum just like stock. By the way the fix for the seeping head gaskets on old Honda fours is to give the new gasket four coats of Gasgacinch, allowing it to dry between coats, before assembly. Of course this assumes the head and cylinder surfaces are not warped or scarred and all O-rings are replaced with good OEM parts.

-Bill
 
spurlock said:
Thanks. I went ahead and posted a full build thread on that bike here if anyone is interested: http://www.dotheton.com/forum/index.php?topic=72261.new#new

I left the cylinder and head unpainted raw aluminum just like stock. By the way the fix for the seeping head gaskets on old Honda fours is to give the new gasket four coats of Gasgacinch, allowing it to dry between coats, before assembly. Of course this assumes the head and cylinder surfaces are not warped or scarred and all O-rings are replaced with good OEM parts.

-Bill

Would Copper Spray-a -Gasket work as well as Gasgacinch? The natural look of the fins on the CB400F looks better than I've seen.
 
grcamna5 said:
Would Copper Spray-a -Gasket work as well as Gasgacinch? The natural look of the fins on the CB400F looks better than I've seen.

I'm not familiar with that product, just know that Gasgacinch works well. I use the multiple coats/drying between coats/drying before assembly as standard procedure on all head gaskets with good results. And it still allows fairly easy disassembly in the future. Not to say other products would not do as well.

One other point though. Sometimes it is hard to tell exactly where an oil leak is coming from. In those cases, clean the engine thoroughly, then spray several coats of athlete's foot dry powder spray onto the area and run the engine until you spot the leak. After the rebuild this bike had a slight seepage around the cylinder that made me crazy since I had just replaced every possible gasket and seal. So I cleaned it up and sprayed some Tinactin athlete's powder spray on the area and took a ride. After a few miles I stopped and inspected. The white spray powder easily revealed the source of the leak, a flaw in the cylinder casting around one of the stud holes which happens to be an oil return passage from the top end. It turned out the engine had a freak casting flaw which had to exist from the factory 40 years ago. The powder allowed me to pinpoint the exact source of the leak. I roughed up the spot with a Dremel tool and applied a dab of epoxy and the leak was no more. But after more riding two different casting flaws showed up in other areas which required more epoxy. Finally the bike is totally leak free. It is very strange that this bike had multiple casting flaws from the factory. They were such slow leaks that it was always assumed to be a bad head gasket, but the athlete's foot powder finally allowed pinpointing the exact spots on the casting that were seeping. Here is the cylinder, coated with the spray powder showing the dark spot at the oil leak.
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-Bill
 
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