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Doms CB550F1 project

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K2-K6:
Agree that the bottom end assessment shows a pretty good condition overall.

Something weird about it as barrels upward are generally well worn, in big contrast to the bottom end. Looks almost like two different engines have been combined that have very different service history.

DomP:

--- Quote from: K2-K6 on September 10, 2023, 08:00:04 PM ---Agree that the bottom end assessment shows a pretty good condition overall.

Something weird about it as barrels upward are generally well worn, in big contrast to the bottom end. Looks almost like two different engines have been combined that have very different service history.

--- End quote ---

I suppose that's always a possibility, the barrels are quite scored and from everyone's views on here I feared I'd find a right mess.  I feel a lot more positive and about it now.

Oddjob:
I'm not so sure Nigel, the damage to the liners could be because of water damage etc rather than wear.

You can see where the primary chain has worn partly through the main oil gallery but you can also see it's rubbed on where the camchain tensioner goes as well, which makes sense of why I'm finding so many damaged at the very bottom. It's even worn a slight groove higher up, clearly it's been lashing around.

If you look closely at the crankshaft Dom you'll find some printed numbers and letters, exactly like the ones you can see on the rods. They can be very hard to see, washing the crank in petrol can help. They are all in a line, so if you find one you should be able to see the others without turning the crank.

Yours crankcase letters are good, the A's can only be yellow or green and the B's can only be green or brown. So no blacks, which is good news.

IF you were going to replace them I'd go with 4 greens in the A journals and 6 Browns in the B journals.

You need to split the rods now and check how those shells have lasted.

DomP:
Thanks Ken, that's good news then re the shell colours.  Are we thinking I need to plastigauge all shells on the crank and conrod then?  excuse my ignorance but what colour or range should I get?

Oddjob:
Well I’m not thinking that. If I could see appreciable wear then maybe I’d recommend that. But I don’t see wear, some slight damage but that’s from contamination.

Now you can either reuse your existing ones or change them for new ones, that’s your choice, remember though that there are 18 shells and most are around £15-20 each, so the best part of £300-400, Then a pair of chains and damper rubbers, another £150. Then gaskets, seals, orings, roller bearings etc.

Not cheap eh

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