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[dazza]

Hi all I just been out for a spin on my 2007 royal enfield 350 Bullet and I noticed this top nuts has a slight leak of oil I tried to nip it up but it seems tight so question is how to stop leak is there a washer fitted underside any advice on a part to purchase off our hosts and advice on fitting ect thanks
https://ibb.co/c7BkwR

[dazza]

[stinkwheel]

There aren't any oilways around there. It's a cylinder head nut and it's not sealed underneath it. Any oil coming up from under there would have found its way into the cylinder head stud tunnel in the barrel casting by creeping under the base gasket. The stud is very close to the edge, there are only a couple of mm of gasket material between the two.



So. It is most likely to be a little bit of oil/breather gas blowing past the base gasket then escaping up there when it gets hot. If it were my bike, I wouldn't worry about it and make a mental note to pay attention to the gasket next time I have the top end off. It is highly unlikely to be causing any problems. Just wipe it away with an oily rag and call it "patina".



If you want to actually fix it, you need a new base gasket, probably fitted with some additional gasket goo round that stud area.



You shouldn't try to tighten that nut byt itself any more. It's one of six cylinder head nuts that should be tightened sequentially using a torque wrench to avoid warping the head.



It could also be blowpast from elsewhere (sparkplug?) that has "crept" into that recess.

[dazza]

Thanks stinkwheel

[Mickey]

Hi Dazza,
Porous heads are common (though less so on 350s) & though it may seem strange it is often evidenced by a leak seeming to come from the spark plug area (also near the de-compressor too).
Whatever the cause as Stinkwheel says, I wouldn't worry about it.
REgards, Mick.

[dazza]

Thanks Mike

[dazza]

Thanks mick