Oil Colour

[stev60]

Bike is 1951 A7, usually if the bike is left a week, I drain the sump, sometimes enough to warrant draining othertimes very little. Last time oil come best described as the color of brownish mud, viscosity felt ok, no smell of petrol getting in. Oil dosent smell burnt and has only done about 100km. Castol 20/50. Ive replaced with morris oil. Engine runs fine no smoke. The oil in there now seems to have gone a little lighter in colour, im used to it going darker. Pump is working perfectly. The magnetic sump plug is showing no debris. The timing side exhaust will sometimes drip a bit of oil at the muffler joint on start up but once wiped away and warmed up this goes, I dont see a connection there but the oil colour is odd.   

[edboy]

a common problem over here and the culprits called rain. nasty water will enter anywhere theres a tiny hole or gap. however if you live in a desert then i m stumped.

[muskrat]

G'day Steve.
I think Ed might be right. Water contamination through very humid air. living in the land of the long grey cloud you get plenty of that. When it warms up everything expands including the air in the tank and motor. As it cools and shrinks it draws in fresh humid air. Moisture in that air will condense and mix with the oil. When the motor is run again and gets hot it should evaporate off but if your only doing short trips the motor might not be getting hot enough.
This used to be a problem with my racer running methanol but can/does happen with petrol motors to a lesser extent.
Cheers

[duTch]

 Don't mean to get away from engine oil, but similarly, I pulled the gearbox inspection cover last week to check if still had some oil and found some patches of rust on a couple of bits (plenty of oil), so that's last weeks job for later today or tomorrow hopefully....I've a bit of slop in the kicker shaft bush, so 'water-from-the -sky' (doesn't happen often) may have run down that when I was at work, parked on side-stand.

  I have *dared* to give it a wash at the ride-in engine-wash place a couple of times, but try and avoid that bit, but I used a 10mm length of SS tube in between the kick-lever and the case, is a good snug fit over that bush, but not on any of the other spare ones (must be oversize). Plan is to stick a couple of 1/16" section 'O' rings inside on the shaft when I get some....should keep oil in and water out (a bit)

[stev60]

Jim
I would think you are right, ive just been starting it regular bringing it up to temp and turning off, weathers been crap so havent ridden it much over winter. There has always been condensation in the exhaust,  leaves  water out of the muffler drain holes. The answer I suppose is if you start it ride it. If condensation forms in the exhaust then its probably under the rocker cover  as well and elsewhere, its in a dry situation but this problem did arrive with winter, three other bikes in same place are ok. The only other thing I thought of was the crankcase breather .
Thanks