Author Topic: Cb 650 1981  (Read 191 times)

Offline sipam

  • Newbie
  • Posts: 11
  • simon
    • View Profile
Cb 650 1981
« on: April 13, 2019, 09:22:45 PM »
Need a left front brake calliper. The threads have gone. Any help gratefully accepted

Offline matthewmosse

  • SOHC Master
  • Posts: 2033
    • View Profile
Re: Cb 650 1981
« Reply #1 on: April 13, 2019, 09:44:31 PM »
Helicoil is a good repair method depending on location of the stripped threads. I have head it said that timeserts are better as they lock into the body of the re tapped item rather than potentially winding back out when next removed - a annoying thing helicoils do occassionally. Failing that the cb650 is not the most common machine, worth looking on sites like cnsl or even Ebay and see if calipers/ seal ( you might find caliper on more bikes with different hangers etc,)  some parts are common to more than 1 bike, widens the pool of doner machines
Got a 500/4 with rust and a sidecar and loadsa bits. nice and original and been round the clock

Offline davefirestorm

  • SOHC Associate
  • Posts: 75
    • View Profile
Re: Cb 650 1981
« Reply #2 on: April 13, 2019, 10:16:51 PM »
What screw thread has gone?

Offline sipam

  • Newbie
  • Posts: 11
  • simon
    • View Profile
Re: Cb 650 1981
« Reply #3 on: April 14, 2019, 10:51:26 AM »
the threads have gone in the housing that holds the 2 parts of the caliper together.
loathed to repair as they ll likely blow apart when applying the brake. its the left hand caliper.
I tried to get bread it with no luck.
new caliper are mega money. need a second hand item. I had replaced all the seals and piston. I'd had it powder coated so it liked the bis. shame

Offline Bryanj

  • SOHC Jedi
  • Posts: 5539
    • View Profile
Re: Cb 650 1981
« Reply #4 on: April 14, 2019, 11:17:26 AM »
A  properly done helicoil is stronger than the oroginal thread in alloy so there should be no worry about it "blowing apart". You need to sort out exactly what yhreaf it is amd get coils long enough.

Offline Laverda120

  • SOHC Pro
  • Posts: 872
  • Honda 400/4 F2
    • View Profile
Re: Cb 650 1981
« Reply #5 on: April 14, 2019, 11:22:43 AM »
I don't think I would trust helicoils in this application either, the first you'll know of a failure will be as you are flying over the car in front!
Have you tried D&K for a s/h caliper, they break bikes so may have something. Are these calipers the same as used on the CB750F2 and other similar Honda's of the era?
You could also try a company called 'Powerhouse' on tel no. 01246 260665. They have received great write-up in the bike press and I've bought stainless pistons from them that they make in-house. They specialise in refurbishment of bike calipers so may be able to help.
Good luck.

Offline Moorey

  • SOHC Pro
  • Posts: 740
    • View Profile
Re: Cb 650 1981
« Reply #6 on: April 14, 2019, 02:32:40 PM »
A  properly done helicoil is stronger than the oroginal thread in alloy so there should be no worry about it "blowing apart". You need to sort out exactly what yhreaf it is amd get coils long enough.

They certainly are as they are made out of 304 stainless. I wouldn't have any worries over using a helicoil. Other option is get it filled with weld, drill and tap back to original.

Offline Bryanj

  • SOHC Jedi
  • Posts: 5539
    • View Profile
Re: Cb 650 1981
« Reply #7 on: April 14, 2019, 02:59:23 PM »
What exact model is it? Check the part number at CMSNL and see if it fits any other Honda.

Offline davefirestorm

  • SOHC Associate
  • Posts: 75
    • View Profile
Re: Cb 650 1981
« Reply #8 on: April 14, 2019, 06:02:00 PM »
Helicoils done properly are stronger than threaded alloy.Helicoils were/are used on all threads holding the all alloy hydraulic steering unit used on the Challenger battle  tank together.
There must be lots of the same calipers lying around due to seized/broken bleed nipples,you just need to i/d it and check interchangeability

Offline Rob62

  • SOHC Pro
  • Posts: 618
  • ZZR1100D9, CB750K4, RD250F, NSR250MC21, C90ZZ
    • View Profile
Re: Cb 650 1981
« Reply #9 on: April 15, 2019, 11:43:13 PM »
My recollection of when we used to fit them at the engineering company I worked for, was that they aren’t easy to do correctly until you’ve had plenty of practice...our guys fitted hundreds eventually but struggled to get them right at the beginning and this was a team of skilled engineers working on freshly machined components......  so yes they are good when fitted correctly but its not easy to achieve a good job especially for the occasional diy mechanic and even more difficult when the workpiece is in poor condition...

Offline davefirestorm

  • SOHC Associate
  • Posts: 75
    • View Profile
Re: Cb 650 1981
« Reply #10 on: April 16, 2019, 08:05:26 AM »
That’s very true and good advice to only let an experienced engineer loose on it.A walk round a decent autojumble is a good source of bits like this Stafford is on last weekend of the month