Honda CB450 K4

1971 CB450 K So, what is it then? First, it's not a "Black Bomber", although it's basically the same frame and engine.

What it is is a US model CB450 K4, which is the later, disk-braked model that we didn't get here in the UK. It's pretty obvious that it's a US model as the seating position is bolt upright, the bars are higher than you'd get in the UK and the foot pegs are in a position that doesn't lend itself to putting on ace bars, anyway.

Not much to say yet, really. TOG found it at the Kempton Park autojumble - I had asked him to keep out an eye for a reasonably priced classic as I had just lost most of the keys for my bikes in a burglary, although the bikes were still in the garage. Just a bit on the immobilised side. I bought it unseen but not unheard over the phone and the seller kindly agreed to drop it off at my place on the way home from the jumble.

Gold-painted caliper. Yuck.

So far it appears to be in rather nice condition, the chrome is all good, the paint isn't bad - although it has been repainted, and God only knows why someone chose to repaint it in the colour scheme of a CB500T, which usually ranks as just about the worst parallel twin Honda ever made. And that's before you notice that someone (possibly the same someone) has painted the brake caliper gold.

Overall it's not bad for a 1971 bike. Probably helped by the fact that it's a US import so at least the chrome hasn't suffered from the best of British weather.


Added 29 June 2004

The CB450 non-airfilter

Well, the above impression didn't last too long. On closer investigation, the air filters don't look too clever - in other words, there aren't any, but the remains look really sporty. See picture on the right. Oh well, at least nobody decided to wrap them in carpet underlay...

Nicely wedged into the battery tray

The battery is the wrong size but some genius has made it fit the slightly, erm, undersized battery tray and the 'leccy bits aren't as healthy as they first appeared as it isn't charging. The current suspicion is that the non-original solid state rectifier is causing these problems as it doesn't appear to be working quite as well as it should. David Silver Spares to the rescue, hopefully.

The air filters are a slightly different story. RHS ones seem to be readily available but none of the usual suppliers can deliver the LHS ones. Googling the part number brought up a potential source in Switzerland; they promptly sent off the filter but after I paid I was told that I had just paid for a RHS filter although I had mentioned several times that the filter I needed was the LHS one, plus the part number I quoted is recognised as the LHS filter by just about everybody else. Oh well, the filter is on the way, let's see which one it is. I'm on the trail of a few other LHS filters, but I believe that if I see them.


Added 3 Feb 2005

The inside of the headlamp bowl

Well, the air filters mentioned above turned out to be for the right side after all, so it wasn't too bad. Unfortunately digging a bit deeper showed that someone had managed to fit an H4 headlight to the bike - glued into the rim with white bathroom silicone, no less - and that had, erm, some repercussions. Like a fried rectifier that stopped the battery from charging. A new rectifier was purchased from David Silver and I'm now getting DC at the battery again instead of AC that boiled the battery. Nice.

The wiring

Another nasty side effect from the H4 headlight "conversion" appears to be that the wiring loom has been butchered somewhat to accommodate the different connectors for the H4 light, plus someone (presumably the same genius who fitted the light) bodged a new cable into the wiring loom to feed the headlight. Given the location where the cable has been spliced into the loom, it looks like part of the loom has been fried by the current drawn by the headlight. Nice.

The wiring

On further inspection of the wiring it appears that not only has the headlamp been grafted in using Scotchblok (always a good idea for something that draws about 5A), some of the wires have also been soldered badly. That they've also been left uninsulated was just a mere detail that I'll quickly gloss over then.

Oh, and the splitter for the throttle cable has been 'fixed' with insulating tape. No wonder the rhs carb opens half an hour after the lhs one. And only after receiving a written invitation, no less.

Never mind, Dave Silver - him again - could provide the throttle cable and some other bits and pieces like NOS mirrors. Unfortunately, neither the headlight rim nor a wiring loom seemed to be available. At least I managed to weedle the part number for the headlight rim out of the sales person so I could go and search for one.

A couple of days' searching on ebay produced both an NOS headlight rim and a main wiring loom for a K6. I hope the latter isn't too different from the K4 loom. They shouldn't be as the bike really didn't change much in the 1970s - the headlight got bigger (but still sealed beam as far as I'm aware) but apart from that it seems that it was mostly the colours that changed, if that.

So now that the wiring loom has made its appearance I can take the bike apart to fit the new old loom. The plan is to use this as an excuse to get the bodywork resprayed as well - I'm not too fond of the black anyway, and why would anyone actually go and make a CB450 looks like a CB500T? Why?


Added 22nd April

I finally got around to fitting the new throttle cable to the bike. So it's only been six months since I got the cable, where's the hurry?

Once the old cable was removed it became clear that the bike didn't want to run properly because the splitter housing of the cable was broken, allowing one of the two cables to flop about and thus open the second carb considerably later. Didn't help the smooth running, that. Fitting the new cable was a pretty easy job as it's only a single "pull" cable, not a push/pull cable as on the CB750 Four of the same era.

This little obstacle out of the way and the carbs balanced by eye the bike started up second kick. It had never done that before. A bit of fettling later and both carbs opened and closed roughly in sync, the engine was warming up properly and once warm, revved smoothly. Well, as smooth as they ever are with that daft points ignition Honda fitted. According to The Fang's website the best thing you can do is fit Newtronic electronic ignition to one of these twins. Incidentally this is exactly what I'm planning to do once I got the bike back together and running.

Unfortunately I got a bit overenthusiastic and managed to drop the bike on the left hand side. Result, one artfully bent gear lever which David Silver confirms, has been unobtainable for some time. Let's hope that I can convince a mate of mine to help me straighten the lever, otherwise I'm in a spot of bother here. Does anyone who's reading this have a spare one flying about? Not a happy bunny I am.

The following weekend - after I had finally found someone who could respray this bike in the colour scheme I want and had some time to work on it this side of the next century - saw me remove most of the bike's bodywork. I left the fork shrouds on as I didn't want to disassemble the forks - the bike has to stay maneuverable - but fortunately David Silver (them again) could supply me with a set of NOS ones. Everything arrived in time, I got the parts taken off in time and the whole collection went to the painter two weeks ago. Yesterday I received a call that the parts should be ready for collection today or tomorrow.  All parts came off easily with the exception of the headlamp shell. The H4 "conversion" fitted to the bike required a few updates to the wiring which I unfortunately had to cut off. Even more unfortunately most of the modifications had been made to the connectors from the switch. Instead of just making an adapters from the old bullet connectors to the new H4 connector, my old friends the Scotchblock came out in force to hook into the wiring, plus a couple of soldered cables. A drunken spider would have been proud of that mess.


Added April 24th

Picture of the repainted tank

Picked up the repainted bodywork, and blimey does it look lovely. The paintwork was done by Bike Craft - I had seen a bike he had repainted in Classic Bike, and as I seem to have misplaced the contact details for the guy who repainted the Corsaro, I contacted Bike Craft instead. He had them done within half the time quoted (which was mainly due to the good condition the parts were in) and given that all he had to work off were two ropey side panels for colour matching and a couple of photos off the Internet I'm rather pleased with the result.

Now all I need is some time to put the bike back together. There isn't that much work left - the biggest job is swapping the wiring loom.


Added June 14th

Finally managed to get started on the wiring loom. The "new" loom I've got is supposedly off a K6, but so far everything seems to match up. Mind you, I haven't managed to get to the bottom of this particular spaghetti bowl yet, the most interesting part is yet to come and that's wiring up everything inside the headlamp bowl. But that's got to wait a little as I have to do the rest of the loom first and then install the new rhs switchgear as well.


Added June 19th 2005

The loom has now mostly been fitted to the bike. So far the only snag is that the '+' connector from the main loom to the wiring has had the ring connector broken off and bodged on. I should be able to carefully remove the rest of the connector and crimp a new one on. It has been made much easier by the fact that someone's decided to solder on the original, so I've somehow got to undo that first.

Apart from this little problem, the rest of the loom connected up. Well, mostly, there are currently two unused connectors near the horn, but I've left one of the horn leads disconnected as I haven't been able to work out which of the two leads it connects to - got a little colour mismatch there, see.

And as you can see from the picture on the right, the whole collection of parts is now beginning to resemble a motorcycle again, although there is still some detail work left to do before I can put it back together and get it tested.

And thanks to "Wicked Uncle Nigel" and his rather better-equipped workshop, the gearlever is now back on the bike and in useable condition.

Some discolouration is noticeable on the parts that he heated up but that'll hopefully polish out to the point where it's hardly noticeable. To satisfy the concours people, I do have another NOS gearlever but I loathe to put that on the bike just in case it bends in a similar fashion if the bike gets dropped again. Needless to say that there aren't any new ones available any more...


Added October 16th 2005

No progress since June, unfortunately. I've moved house and the bike has been sitting in its new home, partially dismantled, more or less patiently waiting while I'm trying to sort out the house and the garage first.

Hopefully I'll be able to restart the restoration in about a month or earlier if I get bored with all the other DIY!


Parts (still) wanted

I'm still looking for a handful of parts for the bike: