SOHC.co.uk Forums > CB500/550
What do we see here?
deltarider:
Thanks Bryan.
K2-K6:
--- Quote from: Oddjob on April 05, 2022, 02:01:52 PM ---Cheers Nigel. Well that looks to be a busted idea, shame but that's sometimes the way things go. I'll have to either buy new ones or plate the old ones after a good polish up to get rid of the pitting etc.
--- End quote ---
Yes Ken, it's these and the conrod bolts that appear to be running the closest to their design limitations out of all of them, and so difficult to make alternative.
Polishing would certainly take them in the right direction though, removing production marks that are sticking out (without removing base material bulk) will improve them in regard to ultimate stress capabilities and a good move with the polishing skills you have used on other parts. If you've a spare to experiment on that would give you good insight as to how they come out.
Plating though, no. It's another process that can cause problems with load performance so I'd stay away from that as a finish.
Oddjob:
Are they not zinc plated initially Nigel? I'd have said yes or they'd rust for fun. By plating I meant zinc not chrome. I wouldn't of course use acid dip to clean them.
K2-K6:
They've not looked it to me, certainly that could be wrong on my part though.
They do look as if they've been rolled to form the waisted section though, which will always improve the corrosion resistance on steel from compressing the outer layers and giving less voids for corrosion to establish.
Manufacturing when quenched is usually in oil too (possibly whale oil then) because it controls the cooling rate, establishing the desired grain structure. When the hot steel is plunged into oil it immediately heats the oil next to it's surface with this effect partially stalling the cool down phase, with this rate critical in how the grains in the steel propogate to make the steel come to it's target tensile specification. Too fast and it heads more brittle, too slow and it stays more malleable. So the goldilocks quench is just right ;D
The oil stage also adds some resistance to corrosion too.
Trigger:
They can be plated BZP but, there are two parts on a SOHC that can't be pickled, Head studs and carb butterfly. The studs have to be in good condition to plate. Here is a picture on this page of plated studs >>>
http://www.sohc.co.uk/index.php/topic,20419.150.html
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