black gear oil

timo · Post by **timo** » 28 Mar 2005, 14:48

hi folks'
every time i change my gear oil iv noticed its black and i dont feel this is right,
i have dropped the bike before in a large puddle, i changed the oil straight away as the oil had turned to cream, but ever since then its generally black , could this still be dirt in the gearbox ,or a sign of something else, i do change the oil every 300 miles or so ,
can any one give me any idears on this.
many thanks timo

CRMR · Post by **CRMR** » 28 Mar 2005, 20:36

The black could be signs of the bike getting abit too hot ,,(check sparkplug rating)and (Water level in rads,)just generaly see if the bike gets too hot quickly,,It could also be carbon ,, This could be blowback from the piston ring ,, ,Do a compression test to test this ,Also check the powervalve is not sticking or clogged ..remove exhaust and look up hole ..whats your piston look like ,,Have you filtered some of the oil on some cloth and tissue to see what the black is???

d5aul · Post by **d5aul** » 29 Mar 2005, 19:30

Wouldnt have thought the oil is being contaminated by Carbon, being a 2 stroke the gearbox oil does not go near the piston. it needs to get past the crank shaft oil seals first.
Try a different brand of oil as it may be the way the oil acts to wear!
I use Silkolene gear oil, it goes in similar colour to cooking oil but always comes out grey, but then I do often go through deep water!

CRMR · Post by **CRMR** » 29 Mar 2005, 19:43

thats soo true (sort ov) . I think i had my fourstroke head on ..The seals could have gone though..I suppose you could take the oil filler cap of and run the engine to see if theres pressure at the hole to check for this .or smoke ,,,,,would be funny if the black bits were tiny bits of black rubber from a seal though eh d5aul but yes i do agree , It could be just a reaction to the oil wearing out ,,

d5aul · Post by **d5aul** » 29 Mar 2005, 22:33

Normally if the crank shaft seals have failed, you would normally find the engine would draw in whatever is behind the seal as the crankcase area is normally negative pressure due to the 2 stroke cycle drawing fuel from the crank to the combustion chamber.
If the gearbox side seal had gone, you loose gearbox oil as it would be drawn into the combustion chamber & then burnt.
If the generator seal had gone, the bike would run like shite as you would be drawing in too much air.

timo · Post by **timo** » 30 Mar 2005, 22:36

thanks for the replys fellas,
its given something to think about,
iv been using silkolean light gear oil, recomended by my local bike shop.
the oil looks more like burn engine oil, but iv havnt lost any gear oil,
the water levels ok although im still getting the odd bit of white foam on the cap,
but the bike does seem a tad on the warm side, i was out at the weekend when the fuel got low the bike started to rev like mad, i turned the reserve on, still revving like mad, tride turning the bike off still it keep on reving . it sorted its self out in the end , and i put it down to being to hot, for it to run on when switched off.iv checked the plug and it was a good brownish colour with no damage.
im not sure if this is connected to the black oil, but anything possible,
however i do think you could be right about about the oil seal , or could it be a gasket.
i have also done a compession test and got a good 100psi.
if it was a seal or gasket would this show up on the test,
once again thanks for your time looks like the next weekend gonna be the wronge sort of dirty weekend. regards timo

Bargos · Post by **Bargos** » 11 Apr 2005, 20:24

Wouldnt worry about what colour it comes out as long as you make sure that you change it regularly - I change mine about once a month, or after two or three rides.

Just look for the usual - very light metal shavings and/or moisture.

timo · Post by **timo** » 11 Apr 2005, 22:52

hi bargos,
im still getting cream on my cap, (sorry if that sounds rude).i cant see it being a crank seal, or gasket, as i have full power.
the oil is getting a better colour with ever change.
so for the moment im gonna put it down to that massive puddle i fell in.and as you say im not gonna worrie for the moment.
the bikes gonig so well i dont really wanna over fix it , if you know what i mean .
thanks to all for your advice ... timo