collapse

www.dimecitycycles.com

www.cognitomoto.com

https://www.townmoto.com/collections/vanson-leathers

www.speedmotoco.com

www.CITYLIMITMOTO.com

www.jadusmotorcycleparts.com

www.lostapostlejewelry.com

www.sparckmoto.com

www.pistonsociety.com


Author Topic: 1982 CB750F... The resto-not  (Read 33025 times)

Offline pidjones

  • Posts: 1049
Re: 1982 CB750F... The resto-not
« Reply #620 on: May 22, 2019, 00:56:25 »
Primary shaft's in the freezer, cozying up to some bison burgers and fish fingers - I'll leave it in there overnight and then hit the bearing with the blowtorch over breakfast.  Pretty sure that's what kitchens are for, and if they're not then no doubt I'll find out the hard way.  Again.
I officially have never seen this thread....
"Love 'em all.... Let God sort 'em out!"

Offline Jimbonaut

  • DTT BOTM WINNER
  • *
  • Posts: 1940
    • Lost Apostle
Re: 1982 CB750F... The resto-not
« Reply #621 on: May 22, 2019, 10:05:19 »
I officially have never seen this thread....
Then please consider yourself welcomed - officially.




Sent from my iPhone using DO THE TON
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Jimbonaut

  • DTT BOTM WINNER
  • *
  • Posts: 1940
    • Lost Apostle
Re: 1982 CB750F... The resto-not
« Reply #622 on: May 22, 2019, 18:09:08 »
Didn't work - I'll bury it back in the freezer and try again tomorrow.  Guess it's with good reason this bearing is jammed on there so tight.
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline pidjones

  • Posts: 1049
Re: 1982 CB750F... The resto-not
« Reply #623 on: May 22, 2019, 21:20:09 »
If you give up and decide on a new bearing (the only reason I'd take it off), you could remove it like we do the headstock lower inner race. Cut the outer race and ball cage off with a rotary tool and cutting wheel. Then carefully cut most of the way through the inner race and smack the slot with a cold chisel or fat screwdriver.
"Love 'em all.... Let God sort 'em out!"

Offline Jimbonaut

  • DTT BOTM WINNER
  • *
  • Posts: 1940
    • Lost Apostle
Re: 1982 CB750F... The resto-not
« Reply #624 on: May 22, 2019, 21:26:15 »
Thereís a good reason for removing the bearing as Iíve recently learnt. Behind it is a housing that contains small, segmented rubber dampers. These can/do wear down - replacing them with new rubber allows for smoother operation of the primary chain and eliminates any chain rattle. Assuming of course that your primary chain is in good condition.


Sent from my iPhone using DO THE TON
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Jimbonaut

  • DTT BOTM WINNER
  • *
  • Posts: 1940
    • Lost Apostle
Re: 1982 CB750F... The resto-not
« Reply #625 on: Jun 13, 2019, 12:06:39 »
Damn it's been a while.  In the end, won ugly.  Had the thing sitting in the freezer for about two weeks - not entirely because I wanted to get it really, really cold but more so because I forgot all about it.  Life/work/summer(ish) getting in the way and that.  Had at it with a bench vise and big chisel and pried the damn thing off.  Bearing still spins cleanly, and with it removed I could finally get at the once-rubber dampers in the primary gear housing -



Good thing too, one of them looked all chewed up -



- and all of them were completely plasticized and cracked -



OEM originals are rare as pope shit but there's a guy over on cb1100f.net who makes perfect replicas.  That'll do me.

I need to switch out some of the lower case main bearings (2 really) as they're showing copper - I'll replace all 5.  Not the upper main bearings though (good plan?) as they look fine.  All the colours have worn off the bearings themselves so that's that out the window, and I'm a little unsure as to where to look for the inked markings on the crank.  Would the inked markings be on the 5 silver coloured parts of the crank (the part that sits in the bearings), or on the lobes?  I can't see diddly.



I do however have it on good authority that replacing the bearings with the loosest replacements (in this case, bearings with a yellow marking) will work just fine - better looser than tighter.  Also, the difference between the different coloured bearings is really fractional apparently, so replacing all 5 lower main bearings with yellows should - I'm assured - be fine.  Anyone done this?
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline Jimbonaut

  • DTT BOTM WINNER
  • *
  • Posts: 1940
    • Lost Apostle
Re: 1982 CB750F... The resto-not
« Reply #626 on: Jun 14, 2019, 13:07:09 »
Learned that the letters (on this engine, BBBBB) stamped into the case refers to the size of the crankshaft bore(s) through the cases.  As the letters are all the same, this means that each of the 5 bore holes are the same size.  The letters are either A, B or C - these letters are then cross-referenced against (long washed off) inked-stamped letters on the crank lobes to determine what size (colour) main bearing shells to use. 

As I need to replace two lower main bearing shells - but the colour markings on both of them has been erased - I'm thinking that, as a couple of the other bearings still have brown markings, that I can replace the worn bearings with brown too.  Again, I'm assuming this because of the BBBBB stamps in the case - indicating that the bores are all the same size.  Bueno?
"I'm telling you Donnie, nuthin' but nuthin' but right"

Offline CrabsAndCylinders

  • DTT SUPPORTER
  • *
  • Posts: 2189
  • Careful With That Axe Eugene
Re: 1982 CB750F... The resto-not
« Reply #627 on: Jun 14, 2019, 20:47:28 »
You're learning the ABC's of engine rebuilding!

Sorry about that.
Lighter, Quicker, Faster.
ZX-14, 900F x 2, 1100F, R100, CBR600, SR500, GT500, RZ350, KZ1000 x 2, Moto Guzzi Lemans lll, CBX550, RD 350, 750 SOHC police special, RG250, TL1000R, GT750, KTM Super Duke 1290 R, Harris/Z-1, Norton 750 Commando, Green 77 KZ650

Offline Nybz

  • Posts: 31
Re: 1982 CB750F... The resto-not
« Reply #628 on: Jun 14, 2019, 22:21:36 »
It is a bit confusing in the Honda manual, but yeah you have to cross reference those stamped marks on the case with the ink stamp on the crank. (Which by now is probably invisible by now)
I think it would be a safe bet just to get yellows...I could see the colour on the sides of my shells. So I just replaced those with the same.




Sent from my iPhone using DO THE TON
1979 CB750 LTD collectors plates
1979 CB750 K current custom rebuild
1980 CB750 F in waiting...

Past bikes
1982 GL1100
1980 CB400

Offline irk miller

  • DTT SUPPORTER
  • *
  • DTT BOTM WINNER
  • *
  • Posts: 9160
  • You've been mostly-dead all day.
Re: 1982 CB750F... The resto-not
« Reply #629 on: Jun 15, 2019, 00:40:27 »
They have a corresponding measurement and service limit. You have to measure them and see what you need, then get the color based on your measurement. Each color has a .005 range.