Author Topic: CB550K3 fork ears compatibility  (Read 2131 times)

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
CB550K3 fork ears compatibility
« on: April 30, 2022, 03:42:11 PM »
I am trying to source a set of fork ears for a 1977 550K3 which I’m trying to bring back to life. After much searching I have found a set in Canada which look identical (they have the extra stem fitting for the indicators) but they are from a CB750. Does anyone know if these parts are interchangeable.

Offline deltarider

  • SOHC Master
  • Posts: 1337
  • My kingdom for a turkey!
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #1 on: April 30, 2022, 04:01:51 PM »

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #2 on: April 30, 2022, 04:26:57 PM »
Different lengths between the 750 and 550, so even though they look identical they are not.

I bought a pair from DS many years ago for a 550F2 which uses exactly the same ears as the K3. They came in a bag labelled F2 but no part number. I kept them for years and years as a just in case pair but got asked for a pair by Graham on here who was restoring an F2 and wanted some NOS ones, I sold him the pair only to find that the ears were actually from a 750F2. They couldn't be made to fit, too long IIRC. So I had them returned and refunded the money.

Finding a pair in decent condition is difficult, not impossible though. Most will be dented in some way or have pitting and be really rusty behind the ears on the strengthening plates.

I do have some decent ones as I'll be restoring my 500/550 this year and bought them as I saw them, I have a NOS pair, a pair off my bike which are decent and I think maybe either another NOS pair or a really good pair, I'd need to check as they are all in a large box in the loft.

I MAY sell a pair, it depends on the offer. I wouldn't sell the NOS pair I don't think though unless the offer was exceptional. Expect to pay roughly £100-150 an ear if NOS, maybe more these days. A decent second hand set, maybe £150 a pair.

The part numbers you need for a UK model are 51602-390-610 and 51602-390-610. They are not the same as most of the rest of the world ones so be aware of this, some of them have male sockets for the indicators for instance and you need the female type with the welded thread insert.

If your interested I can post some pics of the ones I have, I was going to take the ones off my bike for chrome stripping on Tuesday, not because they really need it but just because even one pit in the chrome is too many for me, it has to be perfect or as close to perfect as you can get these days.

Just been and checked, I have 2 NOS left ones, 1 NOS right one, 1 R/H one which was rechromed but the chromer marked the chrome on the back of the tube slightly so he did it for free and the pair off my bike, which others would classify as excellent (no dents) but a couple of chrome pits.
« Last Edit: April 30, 2022, 04:39:14 PM by Oddjob »
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #3 on: April 30, 2022, 05:30:09 PM »
Many thanks for the help guys, particularly the info regarding part numbers. I have got a useable right hand ear, albeit quite rusty as the bike sat in a shed for over 20 years after my mate pranged it and got it well and truly written off. The left ear however is in a couple of pieces as it was that side of the bike that took the full impact in the crash.
I think my mate had kept the wreck in the hopes of one day getting it back to its glory but unfortunately he passed away at the end of last year and the bike was found in his garden shed so a couple of us are trying to restore it as a tribute.
My preference would be to source a matching set but the priority is to at least replace the left one. I’m happy to pay up to £150 for a decent second hand set or around the low £200s for NOS.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #4 on: April 30, 2022, 07:49:19 PM »
I'll post a pic of the pair off my old bike and see what you think. TBH I was kinda surprised just how shiny they were when I unwrapped them from the bubble wrap I'd stored them in. They were brand new when fitted in the late 70s/early 80s and I always used to go OTT on protecting them, so the inside of the tubes were painted in zinc paint and the reinforcing plates were also painted, I must have removed a couple of chips to see what the metal was like underneath and it's bright and shiny like new. They ain't concours, there are a few small chrome pits which is why I put them in the pile for re-chroming but for anyone else but me I'd say they'd jump at the chance of buying them, I'm just a perfectionist on this restoration as it's my last one and must be as perfect as I can make it.

I'll post a pic of the right hand rechromed one as well, TBH I was chatting to the neighbour over the road who's restoring a Velo and he works in a bike shop at weekends. We got talking, as you do, and I mentioned about the amount of chroming I wanted doing, he said an old bloke does all of theirs for a pittance as he's retired but still has the equipment, of course my ears picked right up. So I offered him a spare R/H ear that had a few spots on it, can he strip it I said and I'll polish the metal and remove all the spots/pits etc and then he can have it back for chroming. So a few days later he turns up and says "He's chromed it but for some reason he's scratched it, dunno what on". I didn't want to say "Hang on he's only supposed to have stripped it" as I was getting a good deal and didn't want to chance spoiling that. However the chroming was pretty good, shame about the scratches, which I think was from the buffing machine". He wanted £30 for chroming it, my mate said no way are you paying for that and wouldn't take any money for it. I was going to have it stripped to see if the scratches came off with the chrome/nickel layer but haven't got round to it yet.

Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #5 on: April 30, 2022, 08:27:57 PM »
Ok some pics.

The rechromed right hand ear. Chrome is difficult to photograph, the camera has a tendency to pick up things that aren't really visible to the naked eye. This first pic for instance looks like there are some pits on the chrome but I can't see any. Not cleaned these BTW so excuse finger prints etc



And the back, I thought it was on the back of the tube but in actual fact it's where the ear is welded to the tube. That would be basically invisible on the bike.



And the pair off my bike. Right hand one first. Front and back. Where the ear joins the tube was painted with zinc paint as that's an area which rusts, in case you were wondering.





Left hand one.





Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #6 on: April 30, 2022, 09:33:05 PM »
Bloody hell Oddjob, they are in excellent condition as far as I can tell from those photos. If you want to part with a pair please message me and hopefully we could sort something out.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #7 on: April 30, 2022, 10:15:50 PM »
Which pair interests you the most. The first pair would be one NOS L/H ear and the rechromed R/H ear £200 or the pair off my bike £150. Both include p&p.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #8 on: May 01, 2022, 04:51:04 PM »
Just checking but are the indicator stems long (about 3 inches) tapered a little with male threaded ends?
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #9 on: May 01, 2022, 07:57:04 PM »
That sounds about right but I haven’t managed to get the old stems out yet. They are currently sitting in the garage soaked in WD40 so I’m going to have another go at them tomorrow - I may have to apply a bit of heat.
In answer to your previous question I would be happy to take the used pair off your hands at the price mentioned. I think these will be more in keeping with the rest of the rebuild as I am trying to use as many of the original parts as possible to have a ‘sympathetic’ restoration.

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #10 on: May 02, 2022, 02:51:51 PM »
Let me know when your ready.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #11 on: May 03, 2022, 01:22:11 PM »
I’ve managed to get the stems out of the old ears. They are 63mm long with a diameter of 20mm. The thread is 12mm long with a 12mm diameter. If this all ties in your end I’ll PM you to sort out payment and delivery. [ Guests cannot view attachments ]

Offline Oddjob

  • SOHC Jedi
  • Posts: 4296
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #12 on: May 03, 2022, 02:22:44 PM »
Those are stems from a US model, are you keeping the US indicators which are big dish type or fitting UK style ones. If your going for UK ones that could be a big problem as the front stems are different and the rear ones are as well. The front you can find, but damned hard, the rear are virtually unobtainable. Those stems should fit just fine if your keeping the US style indicators, the UK 550K3 got the exact same indicators as the US 550F.

Does the bike still have it's grab rail fitted?

Also if it's an import it's very likely the left hand switchgear is wrong, the US didn't get the passing/horn button combination we got in the UK, it only has a button exactly like the starter button.

None of these are huge problems it's just that most people tend to want to convert to UK specs when they are doing a restore. There are some other small differences but the switchgear and the indicators are the main ones.
Kids in a the back seat cause accidents.
Accidents in the back seat cause kids.

Offline philward

  • SOHC Jedi
  • Posts: 2795
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #13 on: May 03, 2022, 04:47:49 PM »


Those are stems from a US model, are you keeping the US indicators which are big dish type or fitting UK style ones. If your going for UK ones that could be a big problem as the front stems are different and the rear ones are as well. The front you can find, but damned hard, the rear are virtually unobtainable.

Are these the rear stems Ken - off my 500k2 (converted mine to UK)
If they are worth something, I'll sell them on!



Sent from my moto g(50) using Tapatalk

Current Bikes:-
Honda CB750K2 (1975)
Honda CB500K2 (12/1972)
Honda CR750 Replica (1972)
Honda CB350K0 (1969)
Kawasaki ZZR1100D3 (1995)
Kawasaki ZZR250 (1990) Project (Going on eBay ASAP)

Offline Bookmark1

  • Newbie
  • Posts: 38
    • View Profile
Re: CB550K3 fork ears compatibility
« Reply #14 on: May 03, 2022, 05:30:48 PM »
Hi Oddjob.
The indicators are quite large so, going by what you have said, I would imagine that they are US spec. Both front indicator casings are in very good nick but only one remained totally intact - I will have to get a new lens for the other.
The rear indicators both need lenses and I will have to try and straighten out one of the casings (it is more square than round, lol) but I want to keep them.
Funny thing is the bike was UK registered from new so somebody must have changed the indicators out at some point!
As to a grab rail - it didn’t have one.
Will these fit the fork ears you have as I know there are different specs e.g 12mm and 10mm fittings?

 

SimplePortal 2.3.5 © 2008-2012, SimplePortal