1967 CB450K0 Black Bomber Rebuild - By Royhall

[AshimotoK0]

Thanks for that Ash. The plot just thickened a bit read below.

CB450 K4 vs K5 alternator rotor swap- beware!

I think  have heard about the keyway issue  before Roy but I think Nigel Harris actually has a K5 setup on his Bomber and he's been into Bombers for a really long time, so I need to ask him if he modified anything to get everything to work reliably. It's a case of possibly modifying later parts or ditch having an electric starter altogether. The chances of finding decent K0 parts is pretty slim.

[royhall]

I have been trying to compare your two rotors from the picture. The timing marks look the same in relation to the keyway but it is a bit hard to be sure. He's talking about a 20 degree error and it doesn't look anything like that. The part I need is really 31101-283-013 which covers later K0 to K4. Which one do you have there marked K0? Could I ask a big favour Ash, if I pay the postage both ways could I borrow both rotors to make sure my other parts fit. If it's certain that's the right part I will buy a new one from the pirate but need to be sure first as it's an expensive part. Cheers.

[AshimotoK0]

I have been trying to compare your two rotors from the picture. The timing marks look the same in relation to the keyway but it is a bit hard to be sure. He's talking about a 20 degree error and it doesn't look anything like that. The part I need is really 31101-283-013 which covers later K0 to K4. Which one do you have there marked K0? Could I ask a big favour Ash, if I pay the postage both ways could I borrow both rotors to make sure my other parts fit. If it's certain that's the right part I will buy a new one from the pirate but need to be sure first as it's an expensive part. Cheers.

OK....  pretty heavy though ...and I will need to pack pretty well as the NOS 500T one owes me a few bob.  The Bomber one is Jason's (Woodside on here) as we pooled our spare parts to try to come up with two sets for each of our bikes. Graham Curtis is looking into re-bushing the sprocket part for us using a hardened sleeve. He's just made a beautiful job of rebuilding a Bomber crank from one I donated to him.

https://www.facebook.com/groups/19998773432/permalink/10158733868393433/?comment_id=10158734015688433&reply_comment_id=10158734043888433

[royhall]

Just measured my rotor and its quite a way off the CB500 item. How confident are you with the measurements as mine is very close to the K0 one but not bang on measured with a micrometre. If you used a vernier that may be the difference. Do you think you K0 rotor is part number 31101-283-013 for the later K0? Can I go ahead and borrow the K0 rotor just to try the clutch mechanism and check the timing marks etc before I shell out big money. I can have it back to you fairly quickly, probably as soon as silvers can deliver from the USA warehouse. Let me know the postage and I will get it to you. I don't think there's much point sending the 500T as the sizes are off. Cheers.

[AshimotoK0]

Hi Roy no worries it's over 2kg packed so I may as well send you the two K0 ones I have to compare late & early. (see pic)

I wonder if a knackered late sprocket wheel hub could be machined down to the size to fit the smaller aperture rotor and then hardened.

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[royhall]

I think it's a fully hardened piece anyway. Thanks for the lend that would be perfect. Let me know the postage costs and I will PayPal it. Cheers.

[royhall]

Still not been able to locate the correct rotor for the sprag clutch I have. I am thinking of machining the old one as it's knackered anyway. My thoughts are to clock it up in a four jaw chuck so the taper runs true then turn off the aluminium up to somewhere around the steel riveted part (careful of the screw holes). Then make a stepped steel ring to shrink on to the rotor and then fix with four correctly spaced countersunk screws (to keep the balance right). My only concern is that a steel ring may interfere with the magnetic flux, I considered making an alloy ring but am concerned that the centrifugal forces along with the forces exerted by the starter may cause an unplanned disassembly. Thoughts please.

I am going to reassemble it for now without the starter chain on so I can kickstart it and do the setting up work to get the project finished. But one way or another this is not going to be one of those fully restored Bombers that you see for sale that is perfect except it has no electric starter.

[AshimotoK0]

Bummer Roy.. I would just assemble without the starter for now .. I managed to get a 5 speed rotor/starter clutch assy. assembly from DK that I am  hoping fits my K0 .. must have grabbed it within a short time of them listing it. Let me be the guinea pig to see if it actually fits the K0 properly. I will keep my eyes peeled for another. They accepted 120 for it and it included the chain and motor sprocket .. so at least you know the UK benchmark price for a really nice one. The Americans seem to ask silly money just for the component parts. It's one of those situations where if you wait then something will usually crop up.

[royhall]

Talk about confusing. These are the code numbers for the alternator rotor for what is an almost identical engine.

K0 - Early 31101-283-003
K0 - Later 31101-283-013

K1 - 31101-292-003

K2 - 31101-292-670

K3 - 31101-292-003

K4 - 31101-292-003

K5 - 31101-346-670

K6 - 31101-346-670

K7 - 31101-346-670

I cant find dimensions for any of the above so am unable to match up to the sprag clutch I have got. Why the strange change at K2, don't get it really.

[Bryanj]

 Numbers changes dont surprise me , Honda were trying to cure a known problem

[royhall]

I have finally got to the bottom of the K0 numbers for the rotor. Here we go.

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Neither of these parts fit the sprag clutch that I have indicating that at some point in the past it has been upgraded to the later 5 speed parts. So the hunt is now on for a K1 to K4 rotor, not sure about the K2 as the part number is different.

Just to highlight the difficulty and confusion surrounding this part, CMS have this one up for sale that the part number has as late K0, but from the picture clearly isn't (note the part number at the top of the picture).

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[AshimotoK0]

Not quite sure Roy but  that seems incorrect to me

The rotor with the thicker alloy tabs on the outside has the smaller dia. sprocket hub and was for early K0

The rotor with the thinner alloy tabs on the outside has the larger dia  sprocket hub and used n later K0's and the 500T has the same style tabs

I just bought a later one from early 5 speed CB450 from DK  and it has the thin tabs and the larger diameter sprocket hub.

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[royhall]

No I'm sure it's right. Both the K0 rotors take the smaller sprag clutch. The first one has the thin lugs set back from the outside diameter, the second one has thicker lugs right out to the diameter, but they both have the same internal size. I have had both of these items in my hands to measure and they both came with the remnants of the original Honda box with the part number on them. The one you have as later K0 is a K1 item, the one you have as early K0 is the later one. If that makes sense. You see what I mean about confusion.

[AshimotoK0]

Still confused Roy but I think you are correct about that very early one. However, in your photo the later part labelled the -013 part doesn't look like this?

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[royhall]

Pretty sure CMS have it labelled wrongly.