hi all the oil rubber o ring on my oil cap has split and is allowing it to leak oil. would this cause it to be a pain to start from cold?

my s1 is struggling to start from cold when it does fire it runs lumpy and sometimes on 3 till i give it some revs.

someone has suggested that the oil cap not fitting air tight would cause this?

cheers

 

Assuming your metering head plumbed into the breather system still,then yes this will cause hard starting and rough running due to excess air!
Replace the cap and that should fix your problem.