Hi before i start i would just like to mention that i have tried the search function but all i can find is air leaks....

Ive got a NC30, which looses very little oil over loong periods of time...
The bike has not been run in over 4months now, but i noticed with the rain the trail of oil leading to a patch underneath the bike, i have noticed the oil patch before underneath the bike when it was in use and it seems to be on the side where the kickstand is directly below the engine case...

any ideas? I would have taken a picture if it wasnt for the rain

you'll have to clean it and see what you can see.

it is likely to be the skanky oldchain lube stuck behind the sprocket..or the output seal on the gearbox, or the seal on the shifter...

get it clean adn then you can see it better. if it is only noticeable in the pissing rain then I suspect build up of shit rather than a leak...as you did not mention you are refilling it much?

in the dry weather its always had a slight leak which i could never trace, and id top it up like once a month...
i totally forgot about the leak till i saw the streak of oil in the rain water that traced back to the bike.
ill wait till its abit drier weather and give it all a clean and stuff and maybe even blow talcum powder all over it to help trace the leak?

once it is clean it will be obvious I reckon..

if youa re topping up then you are looking at the output shaft seal - get a look for that on some old threads..

I had a leak that was not obvious. Steam cleaned whole engine, couldn't find it. Eventually spyed this.

Have a similar leak on my NC30, worse when oil topped up full and only seams to appear when bike on side stand. Sprocket and gear leaver shaft seals appear ok. Am thinking it might be sump gasket, as the heads of sump bolts have droplets of oil that align with stain on bottom fairing. I will change sump gasket at next oil change.

Might be worth a look.

magg wrote:Have a similar leak on my NC30, worse when oil topped up full and only seams to appear when bike on side stand. Sprocket and gear leaver shaft seals appear ok. Am thinking it might be sump gasket, as the heads of sump bolts have droplets of oil that align with stain on bottom fairing. I will change sump gasket at next oil change.

Might be worth a look.

I had a similar leak and it was the rocker cover gasket. Photos on page 3 here:

viewtopic.php?f=24&t=34479&start=20

i have cganged the rear rocker gasket last year so doubt its coming from there...
need to change the front one too but its a ballache getting to it
going to give it a good clean now its not raining...

You only need to wash the engine off with some engine degreaser (gunk in a can is good, brush it on, wait 10 minutes and use a stiff brush to scrub it some more and rinse with a hose pipe)

cheap too.

After that start the enigne up and let it warm up until the fan has cut in twice and inspect with a torch and try and find the leak.

Often oil on the sump will be coming from up top (it runs down of course)

Most common points are Rocker box gaskets, either old and broken or incorrectly seated or a combo of both, sprocket output shaft / gear lever shaft can both leak oil and due to usually being covered in chain shit from an uncleaned bike its hard to see the leak.