Honda-SOHC

As you can imagine I was totally gutted when my newly rebuilt 750K0 tacho fell off a shelf and the shaft that the needle fits into snapped off  . When this happens, I believe even pro. gauge restorers write off the alloy cup/shaft/hairspring assembly. However, I am determined to come up with a fix. I stripped down a late model, large diameter N.D. 550 tatty but working tacho that I got for £2 from an auto-jumble. I sussed that the top bearing is neat on this tacho as it is combined with the brass damper tube and is screwed into the top steel bridge and has a tiny locknut. The main section of the 550 shaft is the same as the 750 but,  even though the needle is very similar on both, the needle is slightly thinner and the tapered shaft is sightly smaller in diameter. Even so, I think that you would have to be a hawk eyed, super nerdy anorak (like me) to notice the difference.
So my plan is the tap the top bridge of a 750K0  tacho (I have a spare one to experiment with and I reckon the thread is M4x0.5mm) and fit the 550 damper/bearing tube. Then I will carefully  part off both the 750 broken shaft and the 550 shaft so that I fit the top section of the 550 shaft onto the 750 one, using the top bearing of the 550. I have found a certain size of electrical bootlace ferrule has a  bore diameter very slightly smaller that the tacho shaft diameter but if you take a sharp scalpel you can cut down the sidewall and allowing it to 'snake' a little as you cut, you get a perfect coupler to join the two shafts together. It's probably tight enough but once assembled and tested could be epoxied /Loctited onto the shafts. Luckily the increased diameter of the shaft still fits into the brass damper tube without fouling.
Just waiting for my M4x0.5 taps  to arrive but basically I have nothing to lose and all of the modified parts will be from another 750 gauge I got scrap with the same problem. Or is this all just a pipe-dream 

I did email Peter H about it but the email keeps bouncing back.

Pretty familiar with registering via dating cert. route but anyone know what the procedure is if you have an original USA title document? I have three bikes with USA titles and need to get them registered.

Watching this video that I posted recently, I always thought that plating shops reverse chromed parts in the chroming bath to remove the chrome & nickel layers of plating, in order to  minimise any  damage to the substrate steel. Problem is Chromic acid is really nasty stuff, hard to get hold of and I don't want to be 'Ashimoto of East Yorkshire'  with the local Erin Brockovitch on my back.
However, in the video posting and linked again here, the pro company used sulphuric acid with a couple of 'additives' to reverse plate strip the chrome and nickel from steel parts.
https://www.youtube.com/watch?v=RU9l66_XmDk

I have a few little bits off my C110 50cc Sports to re-chrome and I need them doing ASAP and can't afford  to wait the lead time at Prestige. The other thing is that I need repairs doing to a few parts with silver solder and bronze brazing which means getting the parts stripped, repaired and then back to the chromers so I put together a small setup to have a go myself.

Research on the internet recommends 5% glycerine added to a 50% strength sulphuric acid, the glycerine evidently limits the damage to the steel base metal. Battery acid is weaker than this so I got some One-Shot drain cleaner I have had in my garage for about 10 years. I remember buying it from a plumbing place in Hull and when I asked for it , the smart ar$e behind the counter says " Do you know who John George Haig' was?" .. so me being the  equivalent smart Ar$e replied " Yea he was the Acid Bath murderer in Crawley.' ...So he then plonks the bottle of drain cleaner on the counter and says " Well this stuff is 3 times stronger that the stuff he used''.. " sign here " .. presenting me with some kind of poisons register.

Anyway, the safety data sheet for the drain cleaner (made in good old 'ull by the way Orcadian) states 91% concentrate sulphuric acid, so I mixed the 1 litre bottle with 910 mls of de-ionised water .. Acid to water NOT water to acid, as it was drummed into me as a schoolboy.  It exotherms (heats up) quite a bit so the usually PPE bol*cks applies.... mask , rubber gloves, old clothes blah blah.

I set up a little bath and did everything outside and used a car battery and rheostat (variable resistor) to provide the current and some lead sheet  from my dodgy mate, as the cathode (negative terminal of battery). The anode (positive terminal of battery) is the chrome part to be stripped ... the rheostat is used in series with the positive terminal to control the current.  I reckon you could use combinations of headlamp bulbs to limit the current if you don't have a rheostat.
I  started out being all fancy with a multimeter etc. but they only usually measure up to 10A DC, at best,  so I just adjusted the current until there was loads of fizzing at the electrodes.

I must say it works really well and no real hassle to the base steel as long as you keep your eye on it and don't leave it in the bath any longer than required.

On triple plated parts you are left with the copper layer, so it is obvious that all of the nickel has been stripped off.

What I do with the non-triple plated parts is to paint the part after stripping,  with acid-copper marking solution that the old boys used to use for marking out steel parts. You basically get some copper sulphate dissolved in de-ionised water and add a few drops of sulphuric acid to it. As soon as you paint the de-plated part with the solution it turns a lovely salmon pink and any areas not stripped you will see a different colour patch. The copper plate doesn't really bond to the mild steel  so it easily buffed off afterwards. Proper copper plating is done with cyanide to get the initial copper layer and is very hard to remove without using nasty chemicals.
 
If you look at the rear shock cover in the 2nd photo, this wasn't triple plated but after stripping it was brushed with the copper marking solution and you can clearly see that where the  top part was not fully immersed in the bath and hence is still silver, not salmon pink.

My bath is only small but  my mate is going to donate me 5l of conc. sulphuric acid, in order  to make up a bigger 10 litre bath  .. plus more lead from my dodgy mate of course  ! Sorry , it wasn't me vicar 


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I was expecting this Bomber 450K0 to be an ultra-low mile museum kept, un-restored survivor for this kind of money.

https://www.mecum.com/lots/LV0123-540475/1967-honda-cb450-k0-super-sport/?fbclid=IwAR0GHteBm3dQp2QKYXQ_1jcJYDZ7Y4nTsEf4aFwaLeu_aK_ukzqwfJRKjMg

Notice D.S. was selling also https://www.mecum.com/auctions/las-vegas-motorcycle-2023/collections/david-silver-collection/

Looked like a good buy .. didn't hang around for long .... one of your ex's James possibly?

https://www.classichondamotorcycles.co.uk/bikedetail.aspx?bike=5291

Seller (Charlie) is a great guy to deal with. I bought my C110 off him a couple of months back. He also has his mezzanine floor full of racks of spare parts he sells in addition to bikes.

https://www.mathewsons.co.uk/auction/lot/lot-618---1968-honda-450-ko/?lot=9747&so=0&st=&sto=0&au=29&ef=&et=&ic=False&sd=0&pp=96&pn=7&g=1  [ Guests cannot view attachments ]

This must have been one of the real bargains at the Bonhams Auction due to their lack of knowledge/attention to detail .. 'Circa 1974' my eye .. It's a very early '68 matching numbers UK model CB250 SS with correct tank, guards ,seat and hubs. Assembled 1st month of production. Even the DS museum example doesn't have that correct front hub. Sold basically for scrap value.

https://www.bonhams.com/auction/26978/lot/62/c1974-honda-cb250-frame-no-cb250-1000668-engine-no-cb250e-1000613/?fbclid=IwAR0GjU1-peLOOZGGnp-qAmZO2vMi-AhD373lzBcXHOB9f78T3sfPkZaO2Co

https://www.dropbox.com/s/ugnwcvfg7tb8pqd/81771NCJRS.pdf?dl=0