1971 CB500K0 Resto 3/71 VIN 1000896

[AshimotoK0]

I deliberated over how to remove the yellowy brown film on the inside of the crankcases. Neither my ultrasonic cleaner on maximum sonics and full heating  would touch it. I was reluctant to dig out my 4l  tub of Hydroflouric acid, as this stuff is off the scale in terms of nastiness but a known cleaner used on aluminium (it used to be widely used by car aluminium wheel valeters until they saw sense). However, I found a bottle of weak sulphuric/ Nitric acid mix that a mate mixed me up ages ago, intended for 'desmutting' aluminium prior to anodizing so I decided to try that. Again, pretty nasty stuff but deffo lower league than hydroflouric acid in terms of nastiness.   I tried brushing that on the inside of the cases (obviously keeping it off any bearing surfaces etc.) and that semed to work fairly well. I then pressure washed it off with water and then hot tanked it in my US cleaner bath to removed all traces of the acid.

[AshimotoK0]

Just appreciating what a lovely engine the CB500 is to work on, particularly compared with the CB750.

Still cleaning up the crankcases ready for paint... bit of a tedious task, so doing half an hour here and there until they are prepared enough. I still need to improvise a curing oven for the paint. I kept our old kitchen oven that would have been perfect but that's at work and I am not allowed access to work, so going to try to impovise an oven at home. Using our kitchen oven is a big no-no, as my wife Cathy suffers from quite bad asthma.

Ultrasonically cleaned the cylinder head but still need to clean out the ports as the U/S cleaner softened the carbon  deposits but it's going to need my Dremel and little brushes to clean out properly.  Valves are looking fine after a clean and grinding in, with just under 1mm seat width still, plus valve stem/guide clearance is OK and valve springs well within limits .. a bit of a relief as I was thinking I might have had to send the head to Trigger & Julie for seat recutting etc.

Managed to find a decent counter shaft among my spares....Bryan ... I used one I got for £1 from Newark autojumble, so I can let you have the one back you kindly donated to me when I came down to see you. I fitted all NOS needle roller bearings including the one in the starter ring plus new bearing to the primary shaft (plus I have the other  6205 bearing (new) to fit in the cases). I bought a rare NOS gearbox output bearing (283 part) as a panic, mega money buy, when I first got the bike but the one already fitted to the gearbox shaft was absolutely fine so I didn't fit the NOS one  (may need it for my Bomber engine possibly). All of the gears look fine with no chipping or drive dog wear. Fitted the 8 new primary drive rubbers. So the gearbox is all good to go back now.

Received the 'oil guide B' in the post from Julie ... massive thanks for that.

[Bryanj]

Centre selector in good order mate? And are you fitting the later selector /clutch parts? If so dont polish the original clutch case the required one with mods is slightly different and  that plate you wanted is part of the mod kit.

[AshimotoK0]

Centre selector in good order mate? And are you fitting the later selector /clutch parts? If so dont polish the original clutch case the required one with mods is slightly different and  that plate you wanted is part of the mod kit.

Thanks Bryan .. I think I may just add the mod plate to better lubricate the bearing and stick with the original cover etc as the bike won't be doing many miles and I guess the ones James owns and SteveD's will have the original shift mechanism. Or is that a big no.no?

The centre selecter measured fine and no signs of discolouring ... is there anything else I should be looking for? I do have spares as it's a CB350/250K part but it looked OK to me.

[Bryanj]

It might be that plate that makes it need a different cover, not  sure. The mod was for better gear detent and to locate selector drum better plus better clutch operation so up to you

[Laverda Dave]

What a great thread Ash! I have read the whole thing from start to finish during the past 90 minutes.  You have stopped me from going into my own garage to work on the Triton! Keep the progress reports coming and did you ever complete the CB175 mention in one of your original posts, I have a soft spot for those and the CB160 & CB200 .  I wish I had room in the garage for the CB500KO James has for sale.

[JamesH]

What a great thread Ash! I have read the whole thing from start to finish during the past 90 minutes.  You have stopped me from going into my own garage to work on the Triton! Keep the progress reports coming and did you ever complete the CB175 mention in one of your original posts, I have a soft spot for those and the CB160 & CB200 .  I wish I had room in the garage for the CB500KO James has for sale.

Let's do trade for your restored 400/4 Dave :-)

[AshimotoK0]

What a great thread Ash! I have read the whole thing from start to finish during the past 90 minutes.  You have stopped me from going into my own garage to work on the Triton! Keep the progress reports coming and did you ever complete the CB175 mention in one of your original posts, I have a soft spot for those and the CB160 & CB200 .

Cheers Dave .. I suppose these long winded resto threads are not everones cup of tea but useful if you get a similar bike as a project and need advice.

After I bought the 500K0 & the CB175 from a forum member my list of projects kind of grew as bikes just came along by chance, quite cheaply,  that I normlly always sat on the fence to buy, as they were  all usuall  quite expensive and parts were rare. But  after I got  this 500 I 'acquired' a '64 CB72 and '67 CB450K0 (all found in boxes in a garden in Crawley). Then I got a CD175 sloper press bike, a '66 S90 and a '61 CB92  .. all projects again from the same source but with the mega hard to find bits included in the sale. The CB175K5 still needs it's engine putting together (kickstart mechanism was knacked) but it's not a bike I am going to fully restore as it is low milage and the chrome is lovely, so best left alone ith with almost 50 year patina really.  The exhausts on the CB175 were 'OK' but I found a much nicer set in Japan that I obtailed via my mate Chris who lives there. I did own a CB160 when I was a student but it always seemed a bit dated even then and I much preferred the CB175,  so never had desires to own one again but the engine was ground breaking when released. Same with the C200 90cc.. I had one when I was at school and all of the girls laughed at it ... which left a permanent scar and no real desire to ever own one again.

[mattsz]

Like Dave, just reading through this from the beginning - I've got some time!

The exchange below is from this thread - almost three years ago.  Nurse Julie foreshadows things to come...

Been busy cleaning up and  satinizing the fork lowers...

I thought that said sanitising the first time I read it Ash, I thought, Gosh, he's really giving them forks an intense super clean ...

[AshimotoK0]

Discovered differences in early 500K0 clutch cover compared with the  upgraded one supplied as per Service Bulletin #4.

CB500/4 Service Bulletins

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

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[Bryanj]

Is that where that little oil feed press steel bit fits Ash?

[AshimotoK0]

Is that where that little oil feed press steel bit fits Ash?

Possibly Bryan.. I think I might need to take you up on those upgrade parts if you have any of them,  once all of this nightmare is over mate. Jason found me the little plate but talking to Trigger, every early K0 he's come across for an engine rebuild had those upgrade parts fitted and he he fitted them to the UK one he restored.

I hope I didn't come over as ungrateful when you first offered them .. it's just that I feared for your families health going on an trip to your lock-up on my behalf. I can assemble most of my engine without the clutch for the time being anyway. I will just make sure the screw in my shift drum is free, as part of the upgrade is to replace the shifter plate and pins.. Oodles of other projects to get on with anyway.

[Bryanj]

Ash, give me a bit of time to sort it all, you can build all the rest of the engine except clutch etc as the mod was done in situ.