Help needed to identify my CB500-4

[AshimotoK0]

Had a reply from Honda UK which said the information has to come from Japan and may take up to 6 weeks. I guess this is their std system so waiting with fingers crossed

That happened to me with my CB250K2 but they eventually came up with the info from Japan. I suspect their service has become a lot better in recent years and until they come up with goods you don't have to pay a penny and still much cheaper than VJMC.

[Trigger]

Had a reply from Honda UK which said the information has to come from Japan and may take up to 6 weeks. I guess this is their std system so waiting with fingers crossed

10 years ago i had to get a dating letter from Honda UK for my first UK 500K0 but, on my second one i have been advised to go through Japan. Looks like Honda UK can not be bothered to put past history on computer's   
This is how MCN lost all of its archives and binned thousands of articles when they moved .

[Oddjob]

Honda Japan claim a fire destroyed some of their records and as a result there were gaps in the histories of some bikes. Mine was in one of the gaps, so they claim, and they duly returned my cheque and politely said go away. I wasn't accepting that and eventually I got Honda Europe to check for me, they also hit a dead end BUT they managed to find engine/frame numbers both prior and post mine and were able to say roughly when it was manufactured, not a firm date but a month which was close enough. I must they didn't work this out until I pointed it out by referencing some of Bryans records, gave them an frame number just lower than mine and the date made and same for one just after mine. They got the point and gave me a certificate of manufacture, which as it turns out I didn't need as the Government decided to change the qualifying date and thus mine being an L reg qualified without a dating certificate. Typical.

Honda Europe are far more approachable than HondaUk whop quite frankly are useless. If it involves work they run a mile.

[AshimotoK0]

I’d have asked him why the 500 wasn’t imported at all, only the press bikes were imported as far as I can make out. It’s a brand new model, the 2nd in line four and HondaUK act like it didn’t exist, something wrong there.

This is one question I asked him Ken:-

Hi again Ian,
I live in Willerby, Hull, East Yorkshire...so quite a distance from you I suspect ! There is absolutely no rush at all getting information  for me. It's just really nice to be in touch, at last, with somebody who was with Honda when a lot of my bikes were launched. From what I understand the CB500/4 used gearbox components similar to the CB250/350K and there was a weakness there, which I think they tried to cover up in the States. The faults  were quickly rectified but the USA started selling K0 models in showrooms with the known faults, alongside the K1 and found themselves with a USA law action against them, which lead to a refund being given to some purchasers of the K0. This was the reason I though that maybe the UK stayed clear of the K0 and only introduced the CB500 a year after it's initial launch and only in it's K1 form. There definitely was a UK version of the K0 in the UK (flat handlebars and UK switch-gear etc) but my understanding is that only 4 were officially sold, although quite a number were imported from Europe. 

[Oddjob]

Might be a fault with your logic there Ash, I’d imagine the gearbox fault on the K0 didn’t come to light immediately and Honda would have covered it up for a short while, so unless the US got the 500 many months before the rest of the world it wouldn’t really have been known about for the UK to have declined importing it, and even if your logic is right why not stop selling in all of Europe until they’d fixed the problem. I’m thinking that it could be the press reviews in the UK that prompted HondaUK to say no, the headlight switch problem was something so dangerous that if someone had been killed as a result then the brand would have suffered so badly they decided not to import until Honda had fixed the problem. Someone imports one from Europe and they can legitimately say not our fault, not a UK spec bike, a get out of jail free card in effect.

[AshimotoK0]

Might be a fault with your logic there Ash, I’d imagine the gearbox fault on the K0 didn’t come to light immediately and Honda would have covered it up for a short while, so unless the US got the 500 many months before the rest of the world it wouldn’t really have been known about for the UK to have declined importing it, and even if your logic is right why not stop selling in all of Europe until they’d fixed the problem. I’m thinking that it could be the press reviews in the UK that prompted HondaUK to say no, the headlight switch problem was something so dangerous that if someone had been killed as a result then the brand would have suffered so badly they decided not to import until Honda had fixed the problem. Someone imports one from Europe and they can legitimately say not our fault, not a UK spec bike, a get out of jail free card in effect.

Maybe, TBH my main reason for contacting him was to ask him about the UK CB750 launch / Brighton PP bike and the BBC programme associated with it. My Cb500K0 is a USA, square crankcase, (green) model anyway so I have no particular interest in the UK 500 bikes. your logic doesn't follow either cos the CB750K0  WAS sold in the UK in significant numbers with the same lighting switch..I think  (but had a black kill switch knob)

[Trigger]

Also the UK 750 K1 had the same switch Ash. No complaints or recalls on that one also 

[B11sey]

I think the switch problem is greatly overstated. Ran my K0 for 9 yrs (commuting to work in the dark all winter) before layup and I didn’t even know there was a problem until read it on here

[AshimotoK0]

I think the switch problem is greatly overstated. Ran my K0 for 9 yrs (commuting to work in the dark all winter) before layup and I didn’t even know there was a problem until read it on here

Yes I agree. Quite a few other UK Honda's  around that period had that 'LpH' switch arrangement as well (SS125 etc)
The K0 needle roller seizing on the mainshaft issue was significant though ... my bearing was well and truly fooked and Graham (Trigger) once  showed me a very low mileage K0 countershaft that had been fried by the needle bearing seizing. It's a double-bunched roller type and on mine the alloy carrier cage had disintegrated.

[B11sey]

 The K0 needle roller seizing on the mainshaft issue was significant though ... my bearing was well and truly fooked and Graham (Trigger) once  showed me a very low mileage K0 countershaft that had been fried by the needle bearing seizing. It's a double-bunched roller type and on mine the alloy carrier cage had disintegrated.

I’ll check mine when I split the cases. Are there any proprietary fixes for the K0 gearbox issues?

[AshimotoK0]

The K0 needle roller seizing on the mainshaft issue was significant though ... my bearing was well and truly fooked and Graham (Trigger) once  showed me a very low mileage K0 countershaft that had been fried by the needle bearing seizing. It's a double-bunched roller type and on mine the alloy carrier cage had disintegrated.

I’ll check mine when I split the cases. Are there any proprietary fixes for the K0 gearbox issues?

Yours is a UK / Euro model ... it was probably well sorted out by then. I think the centre shift fork is still prone to wear though so worth checking .. Trigger/Oddjob /Bryan can advise on this better than me.

Here are the Service Bulletins with numbers. from my Dropbox links ... you need service Bulletin #4
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CB500/4 Service Bulletins .. MASSIVE THANKS TO BRYAN JONES FOR COLLECTING THESE AND LOANING FOR ME TO SCAN

https://www.dropbox.com/sh/z8s0vpxu8niqva3/AAC1D8GaKGw_tvX0y2-CTcHaa?dl=0

[Oddjob]

What year did the 750k1 come out though Ash? Was it before the 500k0? I’d imagine it may have been as the 750 came out in 69 and Honda never seem to hang about with a new version so probably 70?

I recall vividly the press slating the 500 for its switchgear, you remember me saying one was written off whilst being tested, what if that’s why it got written off? The press rider claims it left him with no lights on a dark road, he goes off the road and hits something, this may or may not be true, he could have claimed this was the reason for the crash when in fact he was drunk, doesn’t matter, Honda can’t afford to take the chance, if they know about it and someone else has an off or worse gets killed they are liable and completely exposed. So what does Honda do? It removes the offending switch and fits a separate one for on/off. They wouldn’t do this without a damned good reason, it’s expensive to change the production line, expensive to have a completely new switch made and tbh it did spoil the look of the handlebar layout with something that clearly looked to be an afterthought. Just looked at the parts book for the 750 and the light switch is a 750 part number and to me it looks like it wasn’t introduced till 71, it shows on the K0/1 parts lists but there is no part number shown so it may have been an addition to the book added later, pics of one taken at the time don’t show one fitted. So not only did Honda change the 500 specs it also changed the 750 specs and that switch is changed for the 550 for a completely different one.
The gearbox fault wasn’t really well known about at the time for that to have been the reason, Honda did know early enough to change the later engines to avoid the problem but that’s info they would have kept secret in order to not damage sales or reputation of the brand.

These are all just theories, until we know for certain it’s all conjecture

[B11sey]

Ashimoto
My engine number shows it was made before the gearbox mods so I definatly need to check this

[AshimotoK0]

What year did the 750k1 come out though Ash? Was it before the 500k0? I’d imagine it may have been as the 750 came out in 69 and Honda never seem to hang about with a new version so probably 70?

I recall vividly the press slating the 500 for its switchgear, you remember me saying one was written off whilst being tested, what if that’s why it got written off? The press rider claims it left him with no lights on a dark road, he goes off the road and hits something, this may or may not be true, he could have claimed this was the reason for the crash when in fact he was drunk, doesn’t matter, Honda can’t afford to take the chance, if they know about it and someone else has an off or worse gets killed they are liable and completely exposed. So what does Honda do? It removes the offending switch and fits a separate one for on/off. They wouldn’t do this without a damned good reason, it’s expensive to change the production line, expensive to have a completely new switch made and tbh it did spoil the look of the handlebar layout with something that clearly looked to be an afterthought. Just looked at the parts book for the 750 and the light switch is a 750 part number and to me it looks like it wasn’t introduced till 71, it shows on the K0/1 parts lists but there is no part number shown so it may have been an addition to the book added later, pics of one taken at the time don’t show one fitted. So not only did Honda change the 500 specs it also changed the 750 specs and that switch is changed for the 550 for a completely different one.
The gearbox fault wasn’t really well known about at the time for that to have been the reason, Honda did know early enough to change the later engines to avoid the problem but that’s info they would have kept secret in order to not damage sales or reputation of the brand.

These are all just theories, until we know for certain it’s all conjecture

The 750K1 came out in late 1970 in the US (not sure about UK) so before the 500K0 was introduced .
If you look at the 1st full MCM magazine review of the 750 in June 1970 (attached) you will see that rather than slating the headlamp switch the reviewer  was actually in praise of it!

I suppose we will have wait and see if Ian can throw any light on the subject  . He was the Press release man at Honda at the time and was the rider of the bike that was in the 1st UK brochure. If not, we will just have to keep guessing, as I don't know of anyone else around who was with Honda at the time. Perhaps we were a relatively insignificant market and just not offered the model in sufficient quantities to make it viable to sell here.

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[Oddjob]

I think we have to take that review in context Ash, they may be praising the switch as it was so much superior to what the British bikes were offering at the time, I seem to recall they had a switch on the headlight bowl which meant you needed to remove a hand off the bars in order to switch them on, plus it was before the 500 reviews came out and as we know it's defect was pointed out then. As you say though, we won't know for sure until someone who was there says the real reason.

I wonder if an enquiry to one of the magazines of the day, like MotorCycle Mechanics or Bike or any that's still going to see if they know. I'd love to know which magazine wrote one off.