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CB500 K1 Rebuild
Charlie J:
Just trying to post an update on my project but don't seem to be able to attach photos. So this is just a test. Apologies in advance. [ Guests cannot view attachments ]
Nurse Julie:
Great photo 👍👍👍
Charlie J:
Well I managed to attach a photo of the bike so I'll continue with the update. As I said in an earlier post , after getting the engine started amid clouds of exhaust smoke, I thought I'd try an easy fix of changing the valve stem oil seals with the engine in the frame and the cylinder head in-situ. I removed the rocker cover to find that it was in a pretty bad state with bits broken off.
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I'll try and get these areas repaired the best I can. You can also see in the photos that the tappet caps have seen some treatment from a hacksaw in the past in order to sort out where they had been rounded. I had to use 15mm, 16mm and 17mm spanners to remove them!
There is also an irregular shaped hole which I don't think should be there.
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I don't think it does any harm, unless someone can tell me differently? The tachometer drive also looks beyond repair.
I used a Sealey VS1542 Valve Collet Remover/Installer
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to remove the valve springs so I could replace the oil seals without removing the cylinder head. I was a bit apprehensive about using it as I had read some reviews that said the tool was fine for removing the collets but not so good at reinstalling them. However, the tool worked a treat for me. The only slightly tricky part was dealing with the exhaust valves on cylinders 2&3 because of the proximity of the posts for the fuel tank mounting rubbers. But a sharp tap, square on with a 2lb hammer did the trick. I also used the string down the plug hole and rubber band tricks which I read about on this forum. I can't remember who posted them but many thanks anyway.
I reassembled everything and used the damaged rocker cover as it was just to see if the oil seals had done the trick. The bike fired up immediately accompanied by clouds of exhaust smoke. So much for an easy fix! I'll take the head off next and see what that reveals.
Charlie J:
So, next stage in the rebuild was to remove the head and cylinder block to try and identify the cause of the smoking exhaust. I think the photo speaks for itself. [ Guests cannot view attachments ] There is significant pitting to the cylinder sleeves. I’ve checked the cylinder bores and they are standard 58.5mm for the 550 head (which is fitted to the 500 bottom end). It looks to my inexperienced eye that a fairly deep cut will be required to remove the pitting, possibly requiring the 3mm oversize pistons available on eBay from Cruzinimage. A 3mm rebore seems a lot to me, does anyone have any views on this?
I also have a spare 500 cylinder block with standard 56mm liners. The liners have a light coating of rust and two vertical scratches in one of the bores that are just detectable by a finger nail.
This leaves me with a number of options and I can’t decide which is best so would welcome any advice.
3.0mm oversize for the 550 block with new pistons etc
Minimum possible rebore for the 500 block with new pistons etc
2.5mm rebore for the 500 block and reuse the existing pistons with new rings
There may be a problem with using the 500 block because as Hairygit pointed out in a previous reply, the 500 crankcase has been machined to accommodate the larger diameter liners of the 550 block. There is only about a mm or so difference but I don’t know if this will cause a problem, so again, any advice will be greatly appreciated.
Bryanj:
My email is in my profile, send me some pics of the base gasket area on crankcase, the later cases had big enough holes from Honda to take the 550 cylinders.
3mm over is a lot but there are so called 605 kits with liners out there, lots of options.
Mail me and we will discuss it
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