Well, that's what the oil filter is for Ron!
Having built many competition car engines in my dark and shady past that amount of swarf doesn't seem at all out of place on the magnet. The bits that always worried me were the bits that weren't on the magnet but most of those would have been alloy off the pistons.
The test is always to rub the stuff between finger and thumb. It should feel sludgy and the particles should be exceedingly small, much smaller than a splinter for example. Anything bigger than that and you are looking at bits from the gearbox as that knocks more steel off the dogs and cogs and golden coloured sludge is normally from the phosphor-bronze bushes and change mechanism.
Of course, on a car you almost never see the steel swarf or the phosphor-bronze sludge as that is in the gearbox oil which most owners never see.
On a bike with combined engine and gearbox lubrication you will see the debris from the box and that can be scary.
I have always been a believer in the magnetic oil filter 'helpers' such as Filter Plus which assist the oil filter magnet (assuming there is one) and certainly helping if there isn't.
Of course, if you let the dealer do the service then you a) never see the gunge, b)need to tell em not to bin the Filter Plus along with the old filter and c) never take the Filter Plus off the filter (to prevent b) above) before you ride it to the dealers as any swarf collected by the magnet is then free to circulate in the oil on the way
I have lost two top ends off car engines to swarf clogging oilways after a rebore, a head skim or a re-grind of the crank and that despite using long-established machine shops and going over the bits with an airline, a magnetic poky thing and a pressure washer before assembly.
In the old days oilways and camshaft bores were normally through-bored which allowed a decent wash out after the bore but modern maching techniques are getting sneakier and there is no guarantee that what comes off always comes out.
I think modern engines are built to tighter tolerances than back in the day which might account for some of the debris.
Brian (whose dad told him that he only ever worried about the swarf if it was too big to swallow
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