Oil leak :/

[Wrider]

Haven’t ridden bike in few weeks, came to have a blast after work and noticed a small patch of oil. Traced it to the head of the vertical cylinder, oil seems to be seeping out.

Anyone any ideas why it’s happening and more importantly how much it’s gonna cost to fix :/

[350TSS]

Usually it is the little O ring between the barrel and the crank case which would be more expensive as the barrel has to come off. I reckon about 6 hours labour + parts (head gasket , oil, filter, anti freeze, etc etc)

[Luddite]

I don't think the S4R has an o-ring between barrel and crankcase although I believe there is one at the top end of the cylinder head studs.

Have you established exactly where on the head the leak is from? If not, thoroughly clean and degrease the area and try to spot from where the oil escapes. If it's from one of the studs, it could be the top o-ring (assuming it has one!).

Alternatively, is it from the mating surface between the head and barrel? That would sound like a head gasket (any white steam in the exhaust or 'cream' in the oil?).

Don't overlook the cam cover gasket either - if the cover's been off a few times and the gasket's original, it may be due for a change.

Aren't there also covers on either side of each head with their own collection of o-rings?

Seems like there are quite a few opportunities for leaks all told! (I think I'll stick to my obsolete two-valver!).

Let us know what you find. Hope it's not too involved/expensive.

[Darren69]

Rear cylinder base gasket is the usual suspect. Its a thin metal gasket. Early ones had a recess for an o ring later ones did not. Changed around '00-'01 from what I can see mentioned on other forums.

[Wrider]

Good news! I think. Came to the bike today, and there was some oil on the floor but none round the head.
Started her up, no leaking anywhere. On closer inspection I can see there is an oil like substance on the cables tied to the frame, looks kind of reddish?
I think it’s running down from somewhere and oooling?

[Nickj]

Might be melting if you've been out in the rain

In the old days you'd have thought it could be an emulsion of water, rust and oil from a cable but these days (anytime in the last 20 years) they're usually lined so it's possible the linings worn through somewhere.
Can't think of anything else that's oily and reddish used in the motor, the only other thing would be rust oil water combo from the chain or even ACF50 which I think is reddish??

[Mr Gazza]

Softened red paint from petrol seeping from a small crack or perforation?
Oil build up from engine breather, leaking from airbox?
Brake fluid from a leaky reservoir or previous spillage?
Rusty coolant water or red anti-freeze escaping from a faulty or not put on properly rad cap, or a small leak in a pipe, fitting or the rad?
Previous spillage of anti-freeze?
Previous spillage of cleaning agent or wax product?
Boiled sweet spat out by horrid child (or adult) and lodged under tank somewhere?
Wind fall of soft fruit such as Wild (or cultivated) Plum, lodged under tank and oozing juice?
Cache of smaller fruits deposited by small mammal, or deceased small mammal oozing juice?
Airborne food condiment, such as discarded relish or sauce tossed by loutish fast food customer?
As above, high sugar, carbonated, canned drink, or milk based refreshment?
Or could possibly be something far fetched, such as aliens or ekto-plasm?
Why don't you have a good look at the bike instead of the internet?

[slob]

Steel fuel tank or plastic?

[Luddite]

Originally Posted by Wrider

On closer inspection I can see there is an oil like substance on the cables tied to the frame, looks kind of reddish?

What engine oil are you using? Motul is a cherry red colour



Does what you've found match what you can see in the oil level sight glass?

[Nickj]

with the weather getting colder and damper

Through the round window ....