I'm new to CB77's and the 305 engine but not new to bikes. I've had bad bikes all my adult life and know my way around a garage. I've just about completed a nut and bolt restoration of a CB750 (1976) and wanted to go even more old school for my next project. I got the chance to get a rough CB77 and took it.
The bike is bad. I broke all my own rules about buying a project bike. Don't buy it sight unseen (eBay) and with unknown history.. Don't buy a bike with lots of original (expensive) parts missing. Generally speaking, don't be on eBay if there is nothing you really need!
I will post a couple of pics so you can see how silly I have been ...
CB77 restoration by a newbie in Scotland
CB77 restoration by a newbie in Scotland
The frame and swing arm look a little rough in places but are solid with no rot. Front forks are straight. Wheels a little rough but usable. All the rubber is ruined of course. The front fender could be straightened up and used if need be. Carbs look fine but will of course require a full clean and rebuild kit. That's about as much good as I can say for the moment!
I was sold the bike as a 1965 but as far as I can tell it is a 1963. Frame number is 3139XX and the engine number is 6 more than that so is the original with the bike. 1963 is interesting in the UK because it was the first year that age related number plates were introduced. It will either be a non-age related (three letters and three numbers - XXX123) or the first age-related "A" registration (XXX123A). Either is cool. The bad? Where to start ... Engine is seized - not surprisingly. I have the cylinder head off and stripped. It is uniquely put together and it took me a wee while to work out what was happening. The tapered bolt head that locks it in place is odd, but I like how it has been done. Quirky! Sadly, I found lots of bits of metal in the head so it was obvious there was big problems somewhere. There is a stop bolt behind the clutch which I believe is the stopper for the kick start. It was chewed at the end and had clearly been scraping and banging on something. I'm assuming that is where the metal bits have come from. Someone has been inside the engine before me because whatever it was hitting against has been removed. The kickstart gear was nowhere to be found. When the bike was put to rest one of the valves was open. No surprised, that cylinder is in a bad way. The other one is fine (I think). I took the bottom crankcase off and gave the cylinders a tap. One moved, the bad one didn't. I'm not ready to batter it yet, more on that to follow. Everything in the crankcase if gummed up or seized. Should the oil pump turn by hand? It doesn't. I will tear that down and see what is happening inside. Clutch is gummed up and the clutch basket has a lug broken off. I'm thinking a whole new (used) clutch. Too far gone. Both stands gone which is a pain. Rear fender is too far gone unless I go down the Cafe route in which case it will get cut down or disposed of. The seat is toast, but at least I have a chrome trim! The wiring is horrible. Too many parts missing to even begin to list.
I restore parts as much as I can rather than replace. I enjoy a bit of zinc plating and happy to share my method if anyone wants to give it a go. Essentially, rusted bolts get a nice long bath in vinegar before being acid bathed in something more aggressive (33% muriatic acid is a good one) for 20-30 secs. It is then into the zinc electrolysis bath for two or three coats, then a quick chromate dip to finish. The results can be very good indeed and save a fortune on difficult to source parts. Anyway, here's the mad scientist part.
The stuck cylinder is causing me concern. I've done this before and it worked. I have propped up the engine with the cylinders pointing up. I then poured vinegar straight into the cylinder. like a good french dressing, a couple of drops of oil seals it from the elements. I'm going to leave it like that overnight and see if the vinegar can break down the rust and free the rings. If it works, great! If not, I'll let everyone know it is a stupid idea and not to do it. I think it is work a try though. I've tried a washing soda electrolysis bath and it works great on some parts. However, vinegar works in a much more gently way and seem to avoid removing lots of metal somehow. I'm not a chemist, I just know it works well for small and delicate rusted parts and once re-plated look new again. The only question mark is what effect this will have on the piston. Some alloys don't like vinegar and will either turn black or dissolve! Either suits me fine, I will likely be replacing the piston. Welcome to the Forum
Looks like you have a good project there. Not too much missing and you have the unmolested front fender which is good. Take a careful look at your kickstart cover - they are prone to cracking and can be difficult to repair and expensive to buy. I usually begin with something much worse than yours....:-) David Silver has replica exhausts. Have fun! G '60 C77 '60 C72 '62 C72 Dream '63 CL72
'61 CB72 '64 CB77 '65 CB160 '66 Matchless 350 '67 CL77 '67 S90 '77 CB400F
I had a similar seized engine to yours, using 'coca cola' to try and release, I used a piece of angle iron across diagonal studs, drilled and tapped the angle with M10 and used a bolt to press down on the piston with a piece wood between, I have heard people say use a hammer to knock the piston down but I was concerned about shock damage to the crank, others say use heat but it is a steel liner in an aluminium barrel. It took 2 weeks to free off alternating from left to right cylinders and the crank was reusable, it was stripped cleaned and rebuilt. My pistons were midway incidentally, if you have one at TDC and one at BDC or near then you may have problems.
1977 CB400F
1973 CL175 1976 XL175 - Sold 1964 CL72 1966 CA78
63 CB77Hello Eddiebpool
Looks like you have a proper project on your hands there, where about in Scotland are you based. Gordon
Thankfully one of the Pistons is fine, put away with both valves closed near the top. I've soaked in WD40 and it soaks in nicely. The other is the problem. I've been soaking in WD40 too for a week now and I will give it a few firm smacks this weekend to see what's what.
I like the idea of a screw down solution, makes sense. I have some angle steel and might try to fabricate something. I'm thinking a hydraulic solution might work better still. Hammer first, then get creative. I found the bike was originally blue and badly painted over black at some later date. Are there any recommendations on either a good black or blue paint for a hard wearing and original look?
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