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1964 CB77 saga

Clavertonman

Member
Joined
Mar 10, 2025
Total Posts
16
Total likes
10
Location
Bath, UK
I bought the CB77 from the these three pictures
IMG_6038.jpgIMG_6039.jpgIMG_6040.jpg
and a video of the machine running. The last owner (who never rode it and has several CB77s among other bikes, and needed the space) bought it six or seven years ago from a person who apparently used it regularly. Here it is tucked up in the garage.
Home at lasts.jpeg
It was a bit too red when I got it, this was fixed with new tank badges and after a lot of hammering to remove a fork slider jammed with a bit of broken damper valve, replacement the very rough chrome hand painted red fork seal holders, and the fork gaiters with shrouds. It has had a Thai mudflap (fitted reasonably well and looks OK, a Thai chainguard (of which the best that can be said is that it covers the chain - this also involved welding the broken front outer mounting), a Thai clutch cable (just fits, could do with being 50mm longer, and I had to file down the clutch end nipple), a David Silver spares throttle cable- (fitted properly after I'd filed down the throttle end nipple). I don't know how original the paint is, and I've found a reasonable red that will do as I don't intend to properly restore it. Might even repaint it black - the original registration document says black, though subsequent ones say red. The brakes work now, the carbs don't overflow and I've put a quick releaseself sealing petrol coupling in the reserve fuel line, so it's possible to remove the tank without draining it - I'd forgotten about that little surprise ... (though why 15mm OD fuel pipes so they wouldn't fit properly onto the fuel tap). The front mudguard is non standard and will do for now, the speedo packing is positively horrid and a Thai one is in its way - (I await it with interest and anticipation!). The new mirrors and exhausts are from David Silver spares (the old exhausts were missing their baffles and rotted out inside - looks like the case is stainless and the baffle partitions are mild) - and are fitted to pattern pipes that are just slightly the wrong shape. A lot of packing and fiddling and they fit now. Not started it yet so I'll have to see how well the joints seal. On that subject, why would somebody fit two plain washers in the head to pipe joint instead of the proper crush washer - they are easy enough to get - and why a wrong throttle cable (knackered and too short), a wrong clutch cable (would have been OK if it wasn't for the incorrect and rusty chrome curved steel tube section at the handlebar end making it too long and impossible to route). And what's the problem with running the wiring harness correctly? Though the last has meant the discovery of TESA tape - magic stuff! - so it's been divested of the blue and black PVC tape and the split gray tube and rewrapped with some extra wires for indicators and a running light. Thinking that a 61 year old selenium rectifier may not be the most reliable charging solution a Sparck Moto replacement is on its way. I'll leave the alternator wiring through the headlamp switch as it is for now. Most surprising finds so far are the felt rings for the brake cam shafts, and the grease nipples for the kickstart shaft and clutch release. The fifth shot is the key fob I've just spent a horrific sum on - nice. though, isn't it?

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The last shots are of it in its interim state. More to follow, and I hope to be riding it in a month or so This is a first posting, so please forgive me if it's badly formatted
 
I like those style key fobs. I got my first one back in the '70's when they were quite common.
You're right, new ones made from leather and "vintage" examples are pricey now.
 
As you can see, this is not the right knob. The lights were intermittent, so I dismantled the light switch to investigate. a bit of verdigris, but otherwise unworn. reassembled it with dielectric grease and a good clean. The knob was a struggle to refit, and on inspection the holes in the switch and the knob shaft were way out of alignment. If you lifted the shaft away from the headlamp shell, however, it would be possible. When the switch was apart, it could be seen that spring tension held the wiper assembly towards the base, and the wipers were then held against the contacts in the base with more spring pressure. So pulling the shaft out to enable the knob to be screwed on was reducing the spring pressure holding the wipers against the base contacts, and hence causing the intermittency. (I've not tried it out yet, but going by the condition of the wipers and the contacts, I'm pretty confident. Ho Hum !
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I converted my 450 restomod to a CB77 headlight and gauge last year about this time, and I needed the same knob for my parking light switch (that's what I used it for). I found a similar knob called a "chicken head" from a musical instrument supply, intended for use on a guitar to switch pickups. It's not correct either but the price is right.

www.mojotone.com

Mojotone Black Chicken Head Knob

SpecsMojotone Black Chicken Head Knob with set screw
www.mojotone.com www.mojotone.com
 
Looks perfect - I've thrown more money at a new one - I'm sure I spent less on the last CB77 than I've spent on the key fob and light switch knob! I've also found a supplier for the boot that goes over the wiring joints at the back of the crankcase cover. (not the right boot, but a boot - nothing there at the moment apart from half a roll of blue insulating tape. I may replace the socket head screws with JIS cross head screws (or fore head as the manual has it) - somebody does kits of them. I'm working on ways to fit flashing indicators - the UK model never had them. I think the European export LH switch is available, but as the chances of getting all the correct parts is slim and the cost will exceed that of a small house, I'll probably fit an obviously after market period sort of switch, and some modern unobtrusive lights. As it's pre 1980 I can fit an old style black number plate with embossed raised lettering when I can find a suitable one.
 
Clavertonman said:
As it's pre 1980 I can fit an old style black number plate with embossed raised lettering when I can find a suitable one.
Click to expand...
In theory we are supposed to buy BSAU marked plates but I've never had any bother just buying cheap black and white 'show' plates by mail order from Ebay. Guess it depends how fussy your local plod are. Avoids all the hassle of taking your V5 along in person to get ripped off by Halfords or other approved supplier of plates.

For example, slightly smaller than the regulation size, black plate with embossed white letters and bare aluminium surround.

1743953595108.jpeg
 
And here's a screen grab from the UK TV series 'Agatha Raisin', Sir Charles Fraith offering Agatha a pillion ride on his 'vintage motorcycle'. DVLA says it's a 1966 250cc Honda, currently on SORN. Period front number plate. Bike is a CB72, I assume ?

1743954304182.jpeg
 
that plate looks like the sort that I was thinking of - do you remember who supplied it? i seem to see only painted ones at the moment.
 
Yes it is, if it is indeed a 250 cc version. Just like in the Netherlands, the CB77's are very rare, most 77's went to the US.
 
Clavertonman said:
that plate looks like the sort that I was thinking of - do you remember who supplied it? i seem to see only painted ones at the moment.
Click to expand...
Interesting, The supplier of the plate I showed doesn't seem to be trading anymore, and all of the pressed plates currently available seem to have a black background with silver, rather than white, lettering. FWIW, here's my original order:

1743964728759.png
 
Now we are into the spare key saga. I've learned more about keys and blanks than I ever wanted to over the last few days, though knowledge is always useful! The key I have is a cut replacement on a Silca HON27 blank. This will turn successfully clockwise from off through on to park. It will also turn successfully anticlockwise from park through on to off though is a bit notchy from park to on. I got some blanks that claimed to be correct, but wouldn't work because the blade was too narrow. Silca appear to have discontinued their HON27 blank. I ordered a key cut to code which arrived cut on a Silca HON2R blank, this would successfully turn clockwise from off through on to park, though will not turn anticlockwise from park to on, though will turn anticlockwise from on to off. This was the same as one that I ordered cut to code from CMSNL and subsequently ruined by some ill advised filing. After a lot of cleaning and lubrication the newest key will turn anticlockwise from park if it is lifted in the lock. Measuring the key suggests that lifting the key should make it worse. So the difficulties must be down to wear in the lock. After only 61 years. I think I shall call that a result, though. I've ordered some HON2R blanks and will try and get a successful copy cut from the working key. It's great to report, though, that the bike successfully made the journey to get some petrol last week. The only real problem is very leaky fork seals - the tubes look OK so I'll get some new ones. If the tubes are worn they'll have to go to AM Philpot Ltd in Luton to be re hard chromed - I've sent several sets to them, always a fantastic job, they grind off the old plating and replate with 30 microns of hard chrome then grind to size - can't recommend them highly enough. About the same cost as a new set of tubes, but with much deeper plating. There was some not unexpected noise in second gear, and the tappets need adjusting so I can hear how bad the cam chain tensioner is. Happy Days, though
 
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Clavertonman said:
Now we are into the spare key saga. I've learned more about keys and blanks than I ever wanted to over the last few days, though knowledge is always useful! The key I have is a cut replacement on a Silca HON27 blank. This will turn successfully clockwise from off through on to park. It will also turn successfully anticlockwise from park through on to off though is a bit notchy from park to on. I got some blanks that claimed to be correct, but wouldn't work because the blade was too narrow. Silca appear to have discontinued their HON27 blank. I ordered a key cut to code which arrived cut on a Silca HON2R blank, this would successfully turn clockwise from off through on to park, though will not turn anticlockwise from park to on, though will turn anticlockwise from on to off. This was the same as one that I ordered cut to code from CMSNL and subsequently ruined by some ill advised filing. After a lot of cleaning and lubrication the newest key will turn anticlockwise from park if it is lifted in the lock. Measuring the key suggests that lifting the key should make it worse. So the difficulties must be down to wear in the lock. After only 61 years. I think I shall call that a result, though. I've ordered some HON2R blanks and will try and get a successful copy cut from the working key. It's great to report, though, that the bike successfully made the journey to get some petrol last week. The only real problem is very leaky fork seals - the tubes look OK so I'll get some new ones. If the tubes are worn they'll have to go to AM Philpot Ltd in Luton to be re hard chromed - I've sent several sets to them, always a fantastic job, they grind off the old plating and replate with 30 microns of hard chrome then grind to size - can't recommend them highly enough. About the same cost as a new set of tubes, but with much deeper plating. There was some not unexpected noise in second gear, and the tappets need adjusting so I can hear how bad the cam chain tensioner is. Happy Days, though
Click to expand...
Spent a happy afternoon doing the fork seals. The holders needed quite a lot of mud and rubbish washing out, then I could see the seals, remove the retaining circlip, clean everything up and reassemble them. Then I was going to check the valve clearances - plugs removed, rotor cover removed, T mark located, and what's this? no LT mark and C72 stamped on the rotor. As far as I know the rotors are the same apart from the LT mark, and as this rotor seems to give a good alternator output, I'm reluctant to change it. Just have to check the timing the old way, with a degree wheel - though as it starts and runs well, I doubt it's far out. The big question remains, though, where did they find it? Not many C72s where imported into UK as far as I know.
I've since thought about this, and wonder if the higher battery capacity on the C72/77 may be added to by a higher output from the alternator, which may be due to different magnets in the rotor. Can't see it, though - perhaps fellowmembers may know?
 
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Clavertonman said:
Indeed. but they really weren't common here.
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Understood, which makes it all the more curious. The points cover says Type I, but have you removed the points cover so far? I know you mentioned doing valves but of course the points cover doesn't have to be removed to do that. Does it indeed have two sets of points?
 
A very good point. I've not removed the points cover, though it appears to have two coils and two capacitors. Another point that the forum may be able to help with is that everything looks a bit clean under the valve covers. To ease my paranoia, I'd like to check the oil feed to the top end - from memory the oil galleries are closed by the cylinder head top nuts, so if I slacken the relevant ones (from memory the front outer ones) I should get an oil seepage. Sound feasible? As far as the replying to the notification email is concerned, all I can say is Oops! and in mitigation things are harder to do on a phone ....
 
Clearances now set (good as for now, they were pretty close anyway) - I'd forgotten what an utter PITA the inlet ones are to set. I bought a thing called a turnbuckle wrench - don't know what it's for, but the 3.5mm size is a good fit on the square ends on my adjusters. Marked out a pencil line for the T and LT marks (once again, good as for now) and confirmed that the machine does have two sets of points. The timing was about 2 degrees retarded, so I reset it - didn't check the left hand points, though, as I'll have to do a proper timing mark for that. Re oil flow - it seemed pretty oily on closer inspection so I didn't bother to check the flow - in any case I'd have had to cut a slot in a washer to fit in place of the copper washer on the cylinder head nut and it would still have possibly altered the head / barrel joint clamping. I thought of removing the rev counter drive as the oil feed to the rockers passes through the cover and the flow could be checked there. Maybe something to check when the engine is stripped. I'll need to find some tensioner wheels for the cam chain and the primary drive for that, though. Does anybody have any experience if the Sparck Moto regulator? I'm getting 12 volts ish on the battery whether the lights are on or off (I've left the alternator switched through the headlamp switch for now) and I'd have expected 13.2 or higher. There are 15V going into it. The battery floats up to 13.5 volts when charged from the solar charger (No mains power in the garage) which suggests that the battery is OK . I'll send the supplier an email asking for their advice about it. Any replies will be posted here.
 
Clavertonman said:
Indeed. but they really weren't common here.
Click to expand...
Jensen, in the Netherlands, pointed out differences in the rotors. Side by side, one can see the difference in the magnet portions.

Blue Dream CA78

No picture? . Oops. Thanks. They are larger than the smaller bikes I've done recently.
www.vintagehondatwins.com www.vintagehondatwins.com


As ancientdad said, it may simply be lacking the additional scribe marks for timing the 180 degree crank. It should be easy to add the other marks with a scratch awl.
 
Clavertonman said:
Does anybody have any experience if the Sparck Moto regulator? I'm getting 12 volts ish on the battery whether the lights are on or off (I've left the alternator switched through the headlamp switch for now) and I'd have expected 13.2 or higher.
Click to expand...
You won't get 13.2v on any older Honda twin at idle, they don't break even until above about 2500 rpm.
 
I do recommend the Sparcks rec/reg, but needs some mods to mount in original location. It became needed when I converted to LED headlamp bulb.

Blue Dream CA78

1. Next step is to measure stator outputs, I guess. I've just never done it. Do I leave everything connected and measure voltage from the three stator wires to ground? 2. I've already done the resistance checks before I installed the stator and attempted to gauge the magnetic strength of the...
www.vintagehondatwins.com www.vintagehondatwins.com
 
ballbearian said:
I do recommend the Sparcks rec/reg, but needs some mods to mount in original location. It became needed when I converted to LED headlamp bulb.

Blue Dream CA78

1. Next step is to measure stator outputs, I guess. I've just never done it. Do I leave everything connected and measure voltage from the three stator wires to ground? 2. I've already done the resistance checks before I installed the stator and attempted to gauge the magnetic strength of the...
www.vintagehondatwins.com www.vintagehondatwins.com
Click to expand...
the outputs should be measured from the common wire (brown) and the white wire (daytime coils) and the yellow wire (nighttime coils) though they are connected together via the headlamp switch to balance the nighttime requirements. No idea what they should be, though
 
Clavertonman said:
the outputs should be measured from the common wire (brown) and the white wire (daytime coils) and the yellow wire (nighttime coils) though they are connected together via the headlamp switch to balance the nighttime requirements. No idea what they should be, though
Click to expand...
And one has to bear in mind that a lot of voltmeters only read AC correctly around 50Hz - the alternator output is probably very much higher.
 
ancientdad said:
Probably because it isn't pushing high amperage like a car alternator, so the battery voltage won't jump to 13.5 or higher, it takes time at higher rpm.
Click to expand...
That's why I have a phone charger/volt meter on my handlebars for real time monitoring of battery DC volts at all times.
 
I posted a video of one of my 175 engines running a while back. Towards the end of the video you will see the readings on an attached voltmeter, rising from just over 12v at idle, up to a maximum of just over 14v when revved. Engine fitted with a cheap Ebay combination regulator / rectifier.

 
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