Author Topic: Bomber crank refurb  (Read 742 times)

Offline Spitfire

  • SOHC Master
  • Posts: 1488
    • View Profile
Re: Bomber crank refurb
« Reply #15 on: March 04, 2021, 07:03:48 PM »
Those videos kept me amused (and amazed) for quite some time, what fantastic work and he does sound so casual about it all.

Cheers

Dennis
1976 CB750F

1977 CB750F2 In bits

1964 BSA A65R In bits

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: Bomber crank refurb
« Reply #16 on: March 07, 2021, 09:01:50 AM »
Think he has some help with setting up the crankshaft alignment by employing miniature engineers.

https://youtu.be/uTSLUaTjvqw

 ;D

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: Bomber crank refurb
« Reply #17 on: March 07, 2021, 09:19:33 AM »
Apologies for thread drift Ash

https://youtu.be/81UjjSH2iFw

What an amazing process.

Offline AshimotoK0

  • Grogu
  • *
  • Posts: 6123
  • Mad Scientist.... more power Igor ! ٩(̾๏̮̮̃̾๏̃̾)۶
    • View Profile
Re: Bomber crank refurb
« Reply #18 on: March 07, 2021, 09:25:58 AM »
I think the 1st production CB750 cranks in 1969 were ground using a Swiss made machine.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline AshimotoK0

  • Grogu
  • *
  • Posts: 6123
  • Mad Scientist.... more power Igor ! ٩(̾๏̮̮̃̾๏̃̾)۶
    • View Profile
Re: Bomber crank refurb
« Reply #19 on: March 07, 2021, 09:35:22 AM »
Yes amazing machine Nigel. I designed the closed loop water flushing valve system for this company.. which all started in the UK Coalville) . Amazing CNC machines which can spark erode (EDM)  tiny holes to amazing depths and tolerances.

https://www.winbrogroup.com/wam/edmdrilling/
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline royhall

  • SOHC Jedi
  • Posts: 2705
  • Keep biking I'm not quite bankrupt yet
    • View Profile
Re: Bomber crank refurb
« Reply #20 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.
Current bikes:
TriBsa CCM 350 Twin
CB350F in Candy Bacchus Olive
CB750F2 in Candy Apple Red
CB1300SA in Black
Triumph T100C
Suzuki GS1000HC (Top end rebuild underway)
CB450K0 Black Bomber (current project)

Offline AshimotoK0

  • Grogu
  • *
  • Posts: 6123
  • Mad Scientist.... more power Igor ! ٩(̾๏̮̮̃̾๏̃̾)۶
    • View Profile
Re: Bomber crank refurb
« Reply #21 on: March 07, 2021, 10:01:15 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.

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.
“Alright friends, you have seen the heavy groups, now you will see morning maniac music. Believe me, yeah. It’s a new dawn.” Grace Slick, Woodstock '69 .. In the year of the Sandcast.

Offline royhall

  • SOHC Jedi
  • Posts: 2705
  • Keep biking I'm not quite bankrupt yet
    • View Profile
Re: Bomber crank refurb
« Reply #22 on: March 07, 2021, 10:08:21 AM »
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.
Current bikes:
TriBsa CCM 350 Twin
CB350F in Candy Bacchus Olive
CB750F2 in Candy Apple Red
CB1300SA in Black
Triumph T100C
Suzuki GS1000HC (Top end rebuild underway)
CB450K0 Black Bomber (current project)

Offline K2-K6

  • SOHC Jedi
  • Posts: 3414
    • View Profile
Re: Bomber crank refurb
« Reply #23 on: March 07, 2021, 11:24:47 AM »
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.

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal