why does my bike lose power when i fit an air filter??

it is a clean filter new plug /lead

i have leaned off the mixture but still does not rev out??

please help only just started trials and have not a clue

thanks andy connor

Somone once told me that they were told not to put much oil on the air filter, and infact they also said some people run the filter with no oil (i cant bring myself to do this.)

I think i still put too much oil on my filter as im never sure which is the correct, amount. also it takes me about 20mins to wrestle the bloomin thing in there correctly but this is due to the airfilter not having rubber around the top but foam, i found it easier on my old Gasser!

Thats the only input ive got, not too much oil.

Check the rubber hose between the carb and the air box isn't kinked.

As for the filter I just put a bit of WD40 on it with some grease or filter oil round the top edge. Also check the jubilee clips are tight (all 3) and there isn't any splits in the manifold rubber.