I'm just changing the front Rocker Cover Gasket on 2001 X1, currently there is only one 'Umberella' valve (situated at the rear) within the rocker cover assembly. There is a similar cut out toward the front, but no umberella valve in this one.

So question is: should there be one, or two umberella valves?

S1 manual suggests two should be present....

Can't remember about the mushrooms but be very carefull if you go as far as taking rockers off to change lower gasket!!! Not a problem but be aware that the hydraulic lifters (cam followers) extend when not under tension and fill with oil meaning that you can bend a valve if you don't reassemble slowly and let it out again before starting or turning engine over

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I'm a Hornithologist, I get excited by exotic birds.........

one umbrella in each cover, inlet side.
i chamfered the umbrella locate hole slightly on my x1. it lowers the umbrella and gives it an easier seal. Be carefull not to get any swarf in the motor, best done off the bike.

While yer in there, drill out the adjacent oil drain hole to 1/8" - just slightly bigger, really more reaming than drilling. Supposed to help as well. Replace the umbrella valve with new. They don't stay flexible for very long, apparently.

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2006 XB12Ss..... 1998 S1W..... 1996 S2T
We do not need the help of our friends so much as confidence that they will help us when we need it. –Epicurus

Thanks very much for the helpful replies All done

Put less oil in next time

Excellent advice ...