I decided to strip the carbs, the top of the offside carb took some wiggling about to get it off and look what I found
The piston was stuck in the carb top, when I pushed it up, it stayed up. I checked the other carb and it wasn't stuck quite as bad as this one so cleaned out all the black stuff, put them back together and now it starts and runs just fine again
Goodness knows where the black muck came from, I'm wondering if its a combination of my overfilling the dashpots and dirty intake air? I found very loose fitting poor quality foam filters in the airbox, I reckon air was going through the gaps instead of the foam so they're in the bin and I've ordered a pair of big double cone filters to go in the airbox.
