problem cylinder 1

[lammy]

my plug on cylinder one keeps blacking up and misses and back fires when reved or run other cylinders ok engine was rebuilt 6 months ago on 1641cc unleaded kit been fine until now please help checked timing condeners etc doing me ed in please help with

 

[slammedkustom]

you checked the valve settings?
maybe a dodgy HT lead or plug...

 

[currylager]

If the lead, plug and valve clearance are ok then its gotta be worth doing a compression test.