SOHC.co.uk Forums > CB750
750 K2 Strip & Rebuild - help please
taysidedragon:
--- Quote from: Lobo on April 01, 2022, 11:53:30 PM ---Yup, stress / fatigue in engineering more and more to the fore. My bil been very involved with live data vibration monitoring in helicopters - big business now. You have to wonder how the early Comets made it through to production - surely someone might have observed, “er, that radius looks a little tight given the fuselage will be pumped up & down like a balloon over its life….†An interesting story that one.
I digress. Ok, a bit nerdy this one, my engine refurb has morphed into the whole bloody bike. Anyways, the Clutch and brake levers. Was the clear plastic covering intended to be taken off in the pdi. And if not, why is it there? Was it on both levers? Notably the DSS / Yamiya OEM offerings don’t appear to incorporate it. (I ask because I intend to trial clear heat-shrink over the levers. My mint sandcast, which has been my go-to, has it only on one lever…. it seems I may have to return it 😂)
Ta.
--- End quote ---
The Comet story is an interesting one. Being the first jet airliner in service and pressurised, flying at higher speeds and altitudes, it met with different problems never encountered before.
Unfortunately, they learnt the hard way that square windows and metal fatigue don't work. The redesigned Comet had oval windows.
The test tank they used at Farnborough to discover the problem was still there on the airfield well into the Eighties, I got a guided tour of it in the Seventies when my uncle worked there, it's maybe still there?
K2-K6:
The lever's coating appeared to have been dipped originally (from memory) as the pivot end looked like a thick paint that had dried in a tapered type ending.
Most bikes appeared to have it left on going to customer.
There was a coating we used at Farnborough years ago, called Vi-cote and seemed like a spray on clear pvc, but can't trace anything of it now. Perhaps safety has done for it as it was in aerosol can to spray with.
Found this https://starscenic.net/ronan-vinyl-cote-uv-clear.html and wondering if it's anything like that product.
AshimotoK0:
--- Quote from: K2-K6 on April 02, 2022, 10:25:59 AM ---The lever's coating appeared to have been dipped originally (from memory) as the pivot end looked like a thick paint that had dried in a tapered type ending.
Most bikes appeared to have it left on going to customer.
There was a coating we used at Farnborough years ago, called Vi-cote and seemed like a spray on clear pvc, but can't trace anything of it now. Perhaps safety has done for it as it was in aerosol can to spray with.
Found this https://starscenic.net/ronan-vinyl-cote-uv-clear.html and wondering if it's anything like that product.
--- End quote ---
I used some ultra clear heatshrink .. special stuff from RS Components. You chop a bit off and slot it onto the lever and then put in a pre-heated oven at 160 deg C (fan) for a couple of minutes. Agreed original was probably a dip coat. Send some of this to a few people I rate for doing top restos and they thought it was a good solution. Will dig out the RS partno. Ordinary cheapo clear heatshink give a poor result.
https://uk.rs-online.com/web/p/heat-shrink-tubing/7004462
Lobo:
…thanks gents.
Did try a ‘standard’ heat shrink today - not esp impressed. Will soldier on - thanks Ash for the link.
Still unsure what the purpose was…
K2-K6:
Purpose, speculative that it's a relatively low cost way of giving protection to a high wear surface. Most polished surface (that from operation) leaves the alloy easily attacked by road salt, making a poor appearance over time.
Later type with black anodized finish (eatly 80s) appear to do the same thing, still get very polished in use but don't seem to succumb to corrosion.
Presumably the original plastic coat was to preserve how the bike aged at reasonable cost in manufacturing.
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