CB500 using oil?

Hi all just had a txt from my brother in law who owns a cb500.
It has used all the oil in a week but its not leaking on the ground or smoking.

My first thought would be head gaskets but its not smoking.
Its a twin any ideas on what to look for as I will be going around to help him try and solve this problem this afternoon.

Any help would be appreciated
Many thanks Karl.

It surely cant be totally empty without seeing some trace from exhaust or leakage? Bit of a strange one if hes never had troubles with it before

[jambo]

Check the condition of the oil that's still in there. Any leak in the head gasket will leave both the oil and coolant looking like emulsified gunk (not just a bit of white on the inside of the oil cap, that's not a problem).

"All the oil" is probably worth quantifying as well, does he mean "It's gone from F to L on the sight glass / stick" which might be less than 500ml, or does he actually mean it's down to dregs? How certain are you that he's measured correctly each time? Do not start pulling the bike apart until you're quite certain there's a problem, we've had people go a bit mad in the past chasing down an assumed problem without checking it out before hand.

Look over the bike carefully, it may be leaking but he's not noticed where from.

I'd fill it up to the correct level, start the bike from cold, and carefully look and listen to how it's running. If you get blue smoke when cold, but not when the bike warms up it may mean that the oil's just burning better in the hot engine, rather than that it's not leaking when hot for instance.

If I wasn't certain, and the bike seemed to run fine, the airbox wasn't full of oil, the coolant and oil looked clean, then I'd top it up and ask him to keep a record of what he's putting in at what mileage intervals for a couple of weeks. Then I'd know how much it was actually using.

Jambo

Yeah on my cb500 from not on the stick at all to the top of it is around 500ml.

Been round there the amount was not all that really it went from full to nearly empty on the dip stick.

Drained the oil run a strong magnet through it no fillings there, filled her back up run it up to temp all seem fine so I have told him to keep an eye on it.

Its his first bike so I think there may have been a bit of panic but all seems fine.
Thanks for the help.

[Biker Biggles]

Its a good panic to have.Far better to worry about oil level than not know how to check it so never bother.

Patronising question alert... he was measuring the oil with the bike on the centre stand and not the side stand, right?

[maviczap]

Originally Posted by sputnik

Patronising question alert... he was measuring the oil with the bike on the centre stand and not the side stand, right?

Of measured the oil straight after he'd got off it, and it hadn't drained down into the sump

[Fallout]

My Gixxer uses mad oil. 1ml per mile, so goes from F to L in 300 miles. With the help of Sid Squid we suspect its valve stem seals. The symptoms aren't very obvious at first. The oil is blown out the exhaust after leaking into the cylinders during deceleration, idling and start up. You don't see any smoke under throttle, so other riders generally don't notice it.

If its valve seals, check for excessive smoke in the morning. You may think its just water vapour, but it will be thicker and last longer. Also oil will be drawn into the cylinders under deceleration and will collect at idle then be blown out if you pull away quickly. So warm the bike up and try a run down a national speed limit, then engine brake your way to a stand still (dont blip on the down shift). This will suck oil past the seals into the cylinders. Idle for a few moments then give the throttle a good twist. If you see smoke, its oil in the cylinders and probably valve stem seals. If you see smoke when riding at high rpm then it's probably the rings.

The upshot is valve seal leakage doesn't appear to cause any harm, except to your wallet on oil usage, so just live with it. If its the rings it'll just get worse and worse.

[yorkie_chris]

On a CB500 I'd just ignore it and keep topping it up unless it's fouling plugs or otherwise being annoying, they're never worth enough for the hassle of fixing.

My GPshed500 used loads, never changed it just changed filter every few k. Total loss system, oil change every 2000 mile