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Bomber crank refurb

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royhall:
Top job on the crank Ash, but I thought you were going to use the pressure flushing method devised by Jenson? I had mine taken apart and cleaned, you just cant better getting in there and having a look.

AshimotoK0:

--- Quote from: royhall on March 07, 2021, 09:45:52 AM ---Top job on the crank Ash, but I thought you were going to use the pressure flushing method devised by Jenson? I had mine taken apart and cleaned, you just cant better getting in there and having a look.

--- End quote ---

I gave Graham a crank I had to 'experiment' with last year ... he re-furbed it and put it for sale on FB (with my blessing  :) )  and Jensen bought it ... so that kind of made my mind up to let Graham do mine to. Graham reckons that the sludge is so highly compacted on old  Honda cranks that you would never fully remove it without stripping the crank. The design is such that the crud is more inclined to be  deposited in the crank web holes rather than the centrifugal oil filter, located on the end of the crank.

royhall:
The guys that did mine said the exact same thing. I told them about the power flushing thing and they just laughed, That said, when they stripped mine they said there was hardly any crud in there, one of the cleanest he had seen in a while. So probably a waste of money having it done but there was no other way of knowing that information.

K2-K6:
The "crud" I believe comes from effectively taking the oil over temperature locally to bake it in a sticky mollasses type looking residue.

It's something that newer oils are able to avoid and with significant benefit to running things like this.  I don't prescribe to the "old engine, old oil" theory if it can't be proven with good logic why that should be the case.  The so called "synthetic" oils available have very significant advances in this area, susceptibility to heat damage, that just don't compromise in this way. 

From various engines and where this effect is clear, it's usually accumulated at over heat sites rather than pure restrictions.  In other words, temperature within crank components rather than just accumulation of junk getting stuck there.

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