mylovelyhorse
Member
Several years ago, in a set of strangely difficult to quickly explain circumstances, I acquired a history-unknown 1979 CB400A Hondamatic. After some fussing, including new tyres, an oil & filter change, a carb strip & clean, a fresh battery and other TLC I'm pleased to say it ran. I didn't ride it much, in part because it wasn't easy to start on the kick-start and the electric starter mechanism made a horrid screeching sound.
So a while ago I was considering what I might do to to improve the bike when it came upon me that I might do some tinkering about to sort out this and that, like replacing the seals and oil on both forks. I also wanted to fix that starter problem. I don't want a perfect restored vehicle - there's dents in the tank that would prevent that anyhow - but I would like it to run and behave as nicely as possible. At about that time I was offered a whole car-full of spare CB spares in middling to awful condition, including a spare engine that was so externally scruffy it immediately gained the nickname 'the Boat Anchor' on account of it looking like it had been left underwater for a few years. This plus some wheels, a whole host of other things like a pair of clocks, two & a half sets of carbs and so on cost me a total of £230 (about $320). Twice what I paid for the bike itself, mind...
I first partly stripped down the boat anchor, very quickly realising that it was actually - internally only - looking to be in better order than the original engine. Here's some examples - original generator & boat anchor generator assemblies. So at the very least it was (a) practice engine disassembly / reassembly and (b) possible spares for the original engine. Externally, the only usable part was the generator cover and by gum that was going to need some work.
To cut a long story somewhat shorter, the original engine is now on the bench in many, many parts, all of which have been cleaned, labelled and packaged away. All except the crankshaft, rods and shells. Once i removed the starter roller and clutch assembly I found three very unpleasant looking areas of damage. I am not sure what on earth has gone on there but I don't like the look of it at all. Further, the original torx bolts holding the mechanism to the crank had gone, the crank tapped and new allen head bolts put in. Someone has clearly had a good mess about in here and I am not overly impressed with their handiwork. Plus at least one filter appears to have disintegrated (this is mainly paper residue) and the engine not cleaned up.
While the original engine is stamped BBB on the cases and the boat anchor BBA, the boat anchor crankshaft has none of the damage that's on the original. I considered a crankectomy and did some measuring, which nicely justified some tool purchases, so that was a bonus. All looked good and after doing the crank and shells transplant, I applied plastigauge and torqued things up. All measured nicely within tolerance, so after taking advice and discussing things with several extremely knowledgeable engineers of my acquaintance I have decided the swap is to be permanent.
I've also very thoroughly cleaned out the forks, repainted the lower sections, replaced one slider as it had chrome defects in the swept area and reassembled with 140ml of Honda fork oil and new seals. Very little fork oil came out, so goodness knows how long since someone last paid the forks any attention.
I have found the Honda Service Manual, CB400A supplement and parts catalogue to be invaluable as I work on the bike. Parts aren't cheap but I hope - once the bike is finished - to sell off a good number of the spares i have in my lock-up, so that should help replace some of the funds spent. Need to order some gaskets soon, will go for Honda ones where possible.
So that's where the bike stands at the moment. Next job is to replace the balancer weights with solid ones as the rubbers are in poor condition & I have a set from a CB400N, complete with chain and uprated return spring. After that - and further internal cleaning - the engine will very slowly go back together. I say slowly because I am in no rush and I only have one day a week to work on the bike. Also I like to check and recheck things just in case...
So a while ago I was considering what I might do to to improve the bike when it came upon me that I might do some tinkering about to sort out this and that, like replacing the seals and oil on both forks. I also wanted to fix that starter problem. I don't want a perfect restored vehicle - there's dents in the tank that would prevent that anyhow - but I would like it to run and behave as nicely as possible. At about that time I was offered a whole car-full of spare CB spares in middling to awful condition, including a spare engine that was so externally scruffy it immediately gained the nickname 'the Boat Anchor' on account of it looking like it had been left underwater for a few years. This plus some wheels, a whole host of other things like a pair of clocks, two & a half sets of carbs and so on cost me a total of £230 (about $320). Twice what I paid for the bike itself, mind...
I first partly stripped down the boat anchor, very quickly realising that it was actually - internally only - looking to be in better order than the original engine. Here's some examples - original generator & boat anchor generator assemblies. So at the very least it was (a) practice engine disassembly / reassembly and (b) possible spares for the original engine. Externally, the only usable part was the generator cover and by gum that was going to need some work.
To cut a long story somewhat shorter, the original engine is now on the bench in many, many parts, all of which have been cleaned, labelled and packaged away. All except the crankshaft, rods and shells. Once i removed the starter roller and clutch assembly I found three very unpleasant looking areas of damage. I am not sure what on earth has gone on there but I don't like the look of it at all. Further, the original torx bolts holding the mechanism to the crank had gone, the crank tapped and new allen head bolts put in. Someone has clearly had a good mess about in here and I am not overly impressed with their handiwork. Plus at least one filter appears to have disintegrated (this is mainly paper residue) and the engine not cleaned up.
While the original engine is stamped BBB on the cases and the boat anchor BBA, the boat anchor crankshaft has none of the damage that's on the original. I considered a crankectomy and did some measuring, which nicely justified some tool purchases, so that was a bonus. All looked good and after doing the crank and shells transplant, I applied plastigauge and torqued things up. All measured nicely within tolerance, so after taking advice and discussing things with several extremely knowledgeable engineers of my acquaintance I have decided the swap is to be permanent.
I've also very thoroughly cleaned out the forks, repainted the lower sections, replaced one slider as it had chrome defects in the swept area and reassembled with 140ml of Honda fork oil and new seals. Very little fork oil came out, so goodness knows how long since someone last paid the forks any attention.
I have found the Honda Service Manual, CB400A supplement and parts catalogue to be invaluable as I work on the bike. Parts aren't cheap but I hope - once the bike is finished - to sell off a good number of the spares i have in my lock-up, so that should help replace some of the funds spent. Need to order some gaskets soon, will go for Honda ones where possible.
So that's where the bike stands at the moment. Next job is to replace the balancer weights with solid ones as the rubbers are in poor condition & I have a set from a CB400N, complete with chain and uprated return spring. After that - and further internal cleaning - the engine will very slowly go back together. I say slowly because I am in no rush and I only have one day a week to work on the bike. Also I like to check and recheck things just in case...







































