1967 CB450K0 Black Bomber Rebuild - By Royhall

[royhall]

Since the tank has come back from the painters I thought I would have a go at building that up. This is what it used to be like:

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Bit of a crusty mess I think you would agree. This is how the tank looks today. Well pleased with it.

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These are my favourite parts of a rebuild. Makes no difference that the tank wont be going onto the bike for ages, it's like a shot in the arm.

[royhall]

The engine is now finished except for installing the electronic ignition. I shall do that on the bike when I am doing the rest of the wiring. Here's the finished product.

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There may be a break in proceedings now whilst I reassemble the engine on my CB350F so that I can make room in the garage for the Bombers rolling frame.

[royhall]

Morning!

Finished the other jobs so the back end of the garage is now clear meaning I now have a chance to get back to the Bomber. My storage lock-up is only about a half mile away so decided to just push it back to the garage. It was amazing the interest it got from people in the streets, I met an old guy that restores BSA's that I had never met or heard of that lives in the next Avenue. He was round at the garage for nearly two hours. Really nice chap, and he's going to help out with a few items.

Now back in the garage the old girl is looking a bit past her best (sorry about the thumb in photo 1).

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It should be fairly easy to take apart as it looks to be just loosely assembled, plus I have spent weeks soaking everything in Plus-Gas.
An hour and a half later it's packed away in boxes and bags.

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From the look of the parts, this one is going to take quite a time to complete. When i've finished packing it all away, I am going to take it one chunk at a time. I am going to start with the wheels as they require re-chroming, new parts, polishing, and wheel building so I would like to get that aspect underway quickly.

[royhall]

Not sure how old the tyres were but they took some wrestling to get them off, I was laying on top of it on the floor at one point. They were as hard as nails but I got them off in the end. Got the wheels on the bench and first measured and recorded the offset for both wheels. I'm trying to help the wheel builder a bit and also reduce the chances of a mistake. With that in mind, I have decided to carefully remove the old spokes so they can be replicated in stainless. I would normally just angle grind through them to speed up the job. Bit of a long boring job but eventually I got every spoke out intact.

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I have got an OEM replacement rim for the rear wheel as the corrosion on the old one is just too far gone. The front rim is slightly rusty but should be okay for a re-chrome. Unfortunately the rear hub is also scrap as there is extensive cracking around the cush drive areas of the casting. Three out of the four bosses are cracked. So that's the whole wheel that's scrap, hub/spokes/rim. I guess it's to be expected on a 52 year old bike.

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Looks like the search is on for a new rear hub. I need to research a bit more but I think they are the same on all the CB450K models plus the 500T so am hoping the search wont be too hard. But I think I will start with our very own Mr Ashimoto as he appears to have a good stash of Bomber bits so will PM him.

[AshimotoK0]

I have a decent rear hub you can have Roy ... see PM. Just need to go to my stash and get it and check it.

Did you note that Bomber spoke nipples are made of plated brass .. Mick (kettle738) told me about that.

[royhall]

Thanks Ash your a Superstar. Yes I had noted the brass nipples. I am going stainless with the new wheel build so will have to ask the wheel man about that, hopefully he will be able to get silver nipples of some sort.

[royhall]

Had a look at the rear shocks with a mind to rebuilding them. I watched a few YouTube videos about the rebuild and to be honest it didn't look too hard to do. Unfortunately on inspection the shocks look too far gone to be reclaimed. Looks like they are heading to the same place as the rear wheel, ie the bin.

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After a fruitless search for replacements that were either rebuildable or new replicas I had resigned myself to settling for more modern units although they will spoil the look of the bike. I had a look at Hagon who do a shock that looks close but there are internet reports that they foul the chain guard so they are no use.

As we were going to the NEC bike show last Monday, and Hagon have a stall there, I decided to take the shocks and see what they said about it. They had some very helpful people on that stall who said they could build a shock from stock pieces that would not foul the chain guard and would look correct. So at £263 a pair I decided to give them a go, they even asked for my weight to set the spring rate correctly.

That was on the Monday morning, Wednesday afternoon a package arrived containing the shocks. They are the correct length and look correct. They even left off the Hagon stickers at my request. What do you think?

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That's some kind of top service in my opinion. Bit more than I really wanted to pay, but not too bad for a pair of custom built shocks. They are built from polished stainless so they should last well. Even the top black shroud is stainless. Can't try them on the bike to check they really don't foul the chain guard as it's in a thousand pieces but they do look and measure very close to the originals. If the worst happens and they do foul I shall modify the chain guard. Going to be a big scrap weigh in soon.

[taysidedragon]

Well done Hagon. The shocks look fantastic, well worth the money to keep the look.

[Spitfire]

That's great customer service, hope that they fit as well as they look.

Cheers

Dennis

[AshimotoK0]

Well .. I went to my stash of parts this morning and dug out a hub and initially it looked OK but on closer inspection  I think one section is starting to crack like yours Roy. It's hard to assess as I think there are also moulding flash lines around that region too.

I do have others but it will be a week before I can go back and investigate, as I am  away on business most of this week. I would hang fire on sourcing another though as I suspect this may be a common problem. I do have a 500T one somewhere at work too IIRC.

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[royhall]

That's a shame Ash it's a very good hub other than that. Is the crack at 9 o-clock on the picture.  I'm in no rush for it so whenever you can get back in there is good. Can't think of any reason a good welder couldn't repair a crack like that and save an otherwise good piece?

[AshimotoK0]

Well a trip to my stash of bits across town and more bad news. I had two more wheels .. one hub looked perfect but when I cleaned it up there was a minuscule crack on one cush drive area and the other one had a crack too ...nothing a bad as yours Roy but neverthless that's 4 of the b*ggers now including yours that we have found that are cracked to some degree. So I hightailed it to work to find the 500T one I got on a wheel my mate gave me to rob for it's rim and spokes but could't find it.... turned out it was in my garage at home all along    . Inspected it and it  looked very similar to the Bomber ones and all parts of casting around the cush drives are perfect but on closer inspection it's overall a bit taller than the Bomber one.

So that's both of us looking for a rear hub now unless they can be welded. 

I will ask on the Bomber Facebook group if this is a known common fault. My guess is that loads of them from UK bikes with decent mileages will be the to same to some degree. My CB500T one was from a USA import bike my mate got from Summerbud. I bet loads are cracked and nobody has noticed ... the cracks are very difficult to distinguish from casting flash marks in some cases.

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[royhall]

What are they like on sprocket position as it may just be the bearing retainer sleeve is different. Loads of people are selling 500T hubs as 450, is it just the K0 that's different to the rest. have you got a later 450 hub you can check against the K0.

They can't be vastly different as I know it's possible to fit a 500T engine straight into a bomber. Maybe they beefed it up at some point to stop the cracking.

Been watching one all week advertised as cb450/cl450/500T that the seller says has no cracks, he's also sure it will fit so I have put a sniper bid on. Finishes in 16 minutes so I may be the owner of more scrap iron.

Cheers.

[Laverda Dave]

I'm sure there are wheel specialists out there who can repair the cracks. Alloy wheels on early Porches were prone to stress cracking. These can now be repaired (I've seen it done on Wheeler Dealers!). The crack is ground out, filled by welding, dressed and polished. I'm sure they can undertake the same repair on these hubs?

[Trigger]

I can repair those hubs but, it is always a bit of a gamble with jap cast alloy in a stress area. The weld is pure alloy which is stronger than the cast and though it will not crack in the same place the stress can be transferred to another weak part of the cast alloy, that may crack again in the first month of may take a few years. All depends on the stress level . This will happen to about 12% of the hub repairs I do .


Just had a scan of the picture of the hub and those cracks look like they were made when the bushes were pressed in