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SOHC.co.uk Forums => CB500/550 => Topic started by: Gary400/4 on February 19, 2024, 10:53:44 PM

Title: CB550/4K engine strip, Bore scratch
Post by: Gary400/4 on February 19, 2024, 10:53:44 PM
Hello all, I have recently acquired a CB550/4 K project bike to sort out, I have owned these previously and enjoy them more than the CB400/4.
I have stripped the engine to check it over, the engine was literally seized together, it took a lot of effort to remove the cylinder head, the cylinder barrel had accumulation deposits around the front barrel studs. I ended up with a few chipped fins. On inspection of the cylinder bores, the piston ring end gaps were still in service, but not by a lot, so I have purchased a new set of standard rings. On inspection of one of the bores, I note that a scratch is evident about 1cm long by 1mm deep running horizontal in the cylinder wall. I will be honing the bores to help the new rings to bed in. But I am worried about a ring getting snagged on the scratch as it motions up and down at revs. Is this something to be alarmed about?
Title: Re: CB550/4K engine strip, Bore scratch
Post by: taysidedragon on February 20, 2024, 12:35:51 AM
It's difficult to judge without seeing it, but if the scratch is as deep as you say I would be looking at a rebore.
Even then it might be too deep and new barrels or liners may be required.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Laverda Dave on February 20, 2024, 08:31:45 AM
+1 with Gareth's response. 1mm is very deep and I doubt even a +1.00mm rebore will remove it. Considering you now also have chipped fins I would  personally be looking for another barrel but only once I'd got the whole engine apart and inspected especially if it has been sitting seized up.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Johnwebley on February 20, 2024, 08:53:34 AM
If the scratch is only 1cm long and  1mm wide it shouldn't be an issue,

OK, it's not perfect, but the rings are at least 2mm or 3mm wide,

So they shouldn't drop in,
On 2 strokes the ports are far bigger,



Sent from my SM-A546E using Tapatalk

Title: Re: CB550/4K engine strip, Bore scratch
Post by: Bryanj on February 20, 2024, 10:15:45 AM
Do you mean 1mm deep or wide? Wide probably ok but depp not.
If deep its too deep for a max honda size rebore but cruzin do a 3mm oversize kit taking it to 605 ish cc but dont expect a cheap rebore as that is a minimum of 6 passes per bore plus hone!
Title: Re: CB550/4K engine strip, Bore scratch
Post by: McCabe-Thiele (Ted) on February 20, 2024, 10:51:37 AM
As has been said if it's 1mm deep then it's a problem.

I would look for a replacement block, Bryan sourced one for me last year that was spot on. Plus as you know he does rebores as well. He might have a piston kit.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: SteveW on February 20, 2024, 11:21:14 AM
Couldn’t you just replace the liner?
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Gary400/4 on February 20, 2024, 12:22:41 PM
Many thanks for the responses, I especially like the comment by JohnWebly, about 2 stroke rings not snagging on ports.the new rings placed in the bores have an end gap of 0.279mm which is between 0.15 - 0.35mm standard ring gap. This means the bores are well within service. Given the scratch dilemma, I would prefer the replacement liner option. Does anyone know where I could obtain a standard liner with a bore of 58.5 mm?
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Gary400/4 on February 20, 2024, 01:15:30 PM
Hi everyone I have posted a picture of the scratch in the bore, I am still in two minds about using the cylinder?
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Bryanj on February 20, 2024, 01:55:33 PM
No pic seen here
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Johnny4428 on February 20, 2024, 02:04:00 PM
In the gallery Bryan.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Johnny4428 on February 20, 2024, 02:06:14 PM
Hi everyone I have posted a picture of the scratch in the bore, I am still in two minds about using the cylinder?

Gary you need to post pictures as attachment to your post! Gallery is mainly for bike pics!
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Nurse Julie on February 20, 2024, 02:15:14 PM
Just seen photo, that liner is as rough as a bears arse and is useless. You need to source another liner, check the others as well. That's water damage and the damage can easily go right through the liner. It's beyond re bore.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Bryanj on February 20, 2024, 03:28:00 PM
I agree, its scrap
Title: Re: CB550/4K engine strip, Bore scratch
Post by: AshimotoK0 on February 20, 2024, 06:39:31 PM
Just seen photo, that liner is as rough as a bears arse and is useless.

Badger where I come from Julie 😁
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Nurse Julie on February 20, 2024, 06:43:19 PM
Just seen photo, that liner is as rough as a bears arse and is useless.

Badger where I come from Julie 😁
Thats because you're from oooop narth and I'm from darn sarf Ash 😂😂😂😂 I think everyone gets the gist though.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: DomP on February 20, 2024, 08:11:41 PM
Badger here too, Herefordshire
Title: Re: CB550/4K engine strip, Bore scratch
Post by: McCabe-Thiele (Ted) on February 20, 2024, 08:12:49 PM
Just seen photo, that liner is as rough as a bears arse and is useless.

Badger where I come from Julie 😁

Badger where I come from Ash - I think a Badgers rear end has very coarse hairs hence the expression - probably derived from the old working mans sport of Badger Baiting banned in 1835 - it took a tad longer to make the Fox hunting illegal  - 2004 - just another 169 years. I've picked up Road Kill Badger they are weirdly coarse to the touch iirc from 50 years ago when I lived in the countryside.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Laverda Dave on February 20, 2024, 09:28:09 PM
My shaving brush is made with badger hair, maybe I should try using a CB550 liner for a closer shave :-)
Title: Re: CB550/4K engine strip, Bore scratch
Post by: taysidedragon on February 21, 2024, 12:38:41 AM
My shaving brush is made with badger hair, maybe I should try using a CB550 liner for a closer shave :-)

They use a badger's pubes for shaving brushes! 🤣

Probably...
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Bryanj on February 21, 2024, 04:46:08 AM
To the original poster i will see if i have some 550 cylinders for you butvgive me a week
Title: Re: CB550/4K engine strip, Bore scratch
Post by: AshimotoK0 on February 21, 2024, 09:00:17 AM
Just seen photo, that liner is as rough as a bears arse and is useless.

Badger where I come from Julie 😁



Sorry for the flippant hijack of your thread  Gary :-[ :-[

Getting back to to the original question .. I too would be finding a replacement liner/cylinder barrels.
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Rozabikes Tim on February 21, 2024, 10:03:04 AM
My shaving brush is made with badger hair, maybe I should try using a CB550 liner for a closer shave :-)



They use a badger's pubes for shaving brushes! 🤣

Probably...

Don't you lads be catching TB then ...
Title: Re: CB550/4K engine strip, Bore scratch
Post by: Johnwebley on February 21, 2024, 10:34:57 AM
just seen the picture,

yes its toast,

after watching Allen Millyard if you have a large gas BBQ, you could get the liner out OK,  info on You tube,


 liners are available,check this link

  https://westwoodcylinderliners.co.uk/
Title: Re: CB550/4K engine strip, Bore scratch
Post by: DomP on February 21, 2024, 01:14:59 PM
When you're home alone they'll come out in your oven at 220°C
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