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Riding yesterday I noticed that I am generating a lot of oil through the rocker cover breathers pipes meaning the bike was quite low when I got home - I could put this down to how hot it was yesterday but wondered if other explanations could be suggested as it does seem excessive - Thanks Duncan

Coming from a country where average ambient temperatures are higher than here I would expect the oil loss is down to worn bores or rings not our current unusually high temperatures.

I agree, that it's probably not the heat as I've been in the centre of Spain in 40C+ with no problems.
I wondered if all your breather baffles are present; in the rocker boxes and within the breather pipe/s.
Most 500s & 501s have a more closed system with the same rocker box baffles and a catch tank, later 350s may be similar ?
Hope it's an easy fix, Ian

ps Excessive crankcase pressure (bore/ring wear) can push the dip stick out.

There is the plastic baffle in the crank case breather and the Christmas trees are in the rocker covers. -just to check I am understanding this correctly as am not that mechanically minded - a worn bore or rings would mean gases from compression would be pushed back into the crank case -increasing the pressure and forcing oil out -would there not be other symptoms such as oil going the other way into the cylinder and therefore smoke? Which I have not noticed. Could something such as carburation affect engine temperature and therefore oil loss? -Duncan

i very much doubt its carb trouble, i would check plugs for oiling up looking wet , could be broken oil control rings but would expect to see smoke from pipes compare plugs to give an idea to which pot it is , in fact swap plugs for other ones go for a blast and check, make sure oil level is not overfilled as this can cause probs . muller.

make sure oil level is not overfilled as this can cause probs

2.5 litres semi-synth. My drain-plug says use Castrol GTX - most un-Italian!
DD

just the rocker cover breathers? When I had very bad oil 'smoke' from them and the main crankcase breather it was broken oil control rings.

Check the main breather is clear, it should generate just enough resistance (that's what the two baffle sections are for) to push oil mist up to the valve gear.

With ring blowby I'd expect to see oil from all breathers.

Hello -I have just been for a quick 25 mile spin riding quite hard and this reveals the following
When stopped and revving after ride significant drips of oil coming from both rocker breather pipes. Oil mist coming from main engine breather. I have just removed both plugs and there does not seem to be significant oil on them -the front plug does seem to have a whitish deposit though which has not been present before and may suggest this cylinder is running lean The bike is in need of a balance and tune as I have been working on the carbs recently -there is no smoke from the exhausts at all as far as I can tell. This does seem to support the failed oil ring theory unless anyone has any other ideas -thanks -Duncan

If the compression rings are worn but not the oil ring you can get blow by enough to
pressurise the crankcase and blow oil out of the breathers but not show any blue
smoke out of the exhaust.
Maybe a compression test?

Is the oil properly black? When did you last change it or ride it hard for a long time?
Could it be moisture in the oil from lack of recent use?

David

I have decided to strip the pots and have a look -I have never got past the heads before on a bike so any advice welcome - would it be best to do in frame or dropping the engine for ease of access and cleanliness as I have to work outside-and there is no one to get annoyed about an engine in bits in the living room -Thanks Duncan

Going to see if I can borrow a friends compression tester -what should the readings be? Gave it a little tune for one last ride before I decide to take it apart -running well seemingly but stil that drip of oil and mist from the main breather -ho hum best get on with it

My 350sports with nicasil has 13 and 12.5 bar

My drumbrake sports with new oversize-pistons (62.4) has 12-12 bar (after 3000km)

Hi Dunk,
Probably best check your piston rings, or valve guides. Either the rings may have a cracked or the valve guides worn. This is what I found with mine also she would run hard then rough plus the same process with the oil.

Cheers

Brett