hope you clever people can help. i,m on my first rebuild and posted some questions ages ago and then decided to start from scratch because all i had was a bike that wouldn,t start but just backfired. Right the crank/conrod is all good.its had new piston rings and the barrel is sound.(so far so good) i,ve used another cylinder head as i thought there may be a problem with the valve guides in mine (although its old it all looks good so i,ve re ground my valves into it )and also used another rocker box. the valve timing was set on the bench before the cylinder head was refitted so i believe that its spot on. its now back in the bike and has really good compression and bright spark. but its not even firing. i don,t think the plugs getting wet . i,ve had the carb to bits on the bench and it all looks o.k. but when its fitted to the bike and you turn the petrol tap on it floods everywhere through the tickle valve.i,ve just removed the rubber connection between the carb and the air filter and when you turn the engine over petrol is coming out of the carb where the rubber joins the carb.any help would be appreciated.