Hi pete,im glad you found the problem i thought it was air flow as its a classic symptom of what you were describing,the air leak at the diaphragm would have stopped the diaprgam from lifting up when the air is drawn up underneath it and therefore not allowing the slide to lift up. bb and myself always try out best to help out as do the other techies.have a happy new year on your fast scooter the dylans are a great scooter and very reliable and economicle as well as being quick for a four stroke.
adam bike doctor(of milton keynes motorcycle centre)
December 2010