Perplexing ! Twin runs one cylinder only

Engine re built after blow up last year . It is an XS 650 engine we have a spark we have fuel going in we have good compression, timing . No faults that we can see . So at the moment we are flummoxed . The bike runs on a PMA ignition unit . Which is working fine as we have sparking . Carbs have been cleaned etc . Any thoughts , anyone had experience of this ?

have you dropped the sprak plugs as one may not be sparking when its under compression and have you swapped the leads over to see what happens then if you have a spark when plug is out of the head then its either breaking down under load or there is a lack of fuel going into that cylinder

Thanks for the reply eastanglianbiker , i have had a result ! It turns out the fuel was the problem namely the floats

Unfortunately my lack of experience with bikes had allowed me to effectively insert the floats upside down .mthey are mikuni carbs where the floats slide up and down rods that are fixed into the base of the float chamber as opposed to pivoting in the usual way . Upon re fitting the parts to the carb I unknowingly put them upside down . I had no idea there was a top and bottom to them ! My mate spent a long time sussing all this out , I feel a right chump he called me a right C##t LOL all in good spirits !

at least its now running well done

at least its now running well done

Indeed , I actually took it out for aliitle run and it's goes well , even better than before . I will need to improve the front brake and front suspension . Initially a case of servicing them as I have no idea of its service history and Neither are just not good enough at the moment .