Cb100n what can anyone tell me about these?

[matthewmosse]

I had an old friend from way back when I was a teen visit the other day, he had a quick go on my rebel 125 (well a few goes) and is now hooked on the idea of motorbikes, so much so that he has pretty well streight off bought a cb100n off ebay. Looks ok, but has had an engine rebuild and rattles a bit when running. So, are there any common weak points, or owner rebuild mistakes that might be first obvious checks for him to do?

[hairygit]

Great little bikes back in the day! The major problem that occurs is general neglect by the owners (usually ham fisted teenagers), and routine neglect of things like oil changes. This can be very difficult to deal with, as the cam runs directly in the head, like 400/4, 550/4 and 550/4, but with a roller bearing crank the first thing to fail is the cam and head. Engine parts are very scarce nowadays, even D.S.S struggled to get some parts for one of his museum bikes, Honda just didn't expect them to last, and most of them were scrapped more than 20years ago. You MIGHT be lucky and find an okay head/cam for sale somewhere, but I doubt it. Good luck with it though! 

[matthewmosse]

If that is what is rattling, I think I can rapidly direct my mate to a good fix, I had a KL 250 where the cam had totalled the head bearing, a mate with a bike shop got it machined up with a phosphur bronze insert to replace the knackered bearing surface. £65 or so well spent. I won't know til my mate collects the bike and investigates further, it is his first bike too.

[matthewmosse]

Well, he picks it up today, I wont be able to offer advise to him streight away as he is in Guilford which is a very long way, but sounds like he bought himself a mixed bag of fun, rebuilt engine using some nos bits by a previous owner, leaks oil and engine described as noisy, but 100% complete and has extras. Really depends on if the bikes engine being noisy is just a relative thing, compared to other engines, or if it really is properly noisy...