Have fitted new points condenser and spark plug. Bike won't tickover, the air screw and throttle slide screw have no effect. The pilot jet is a 40 and main jet 123 as checked by Bultaco uk. I have had the float level and needle up and down no difference - bing carb. It starts first or second kick but just won't tickover yet you can keep it at a near acceptable tickover a speed on the throttle cable. It revs slowly. I took the silencer off (original big black thing) and was going to see dremel it and repack it but it blows through fairly easily and I just can't see it being that that is causing the issue. Any ideas? Where is the advance retard on these? I bought the manual but it makes a new 'cut n paste' Haynes one look impressive..Thanks P.S. we had it going in the field and it went quite well though, just seems low speed. The slide is well worn but it doesn't rattle.