any of you wizz kids out there could help me i have timed my rebuilt b31 it is slightly off it is timed correctly with the slack wire advance lever about 1/8 retarded surely this should in this setting start all i get is either 2 firering strokes or a spit back through the carb and i really could do with an apprentice with plenty of weight and a good kick

I started my b31 at full advance with no problems. It started first or second kick every time. Pull the decompression lever in and let it out as you kick this makes it easy.

B31s will generally start on a fully advanced setting. I usually retard them a little only if they kick back.
From your description it sounds as if the timing is incorrectly set...did you set it with the lever in the fully advanced position and on the correct stroke? (the compression stroke)..and did you check it after setting?...Ian

email (option): ian@wright52.plus.com

yes ian i did all that i timed it up without the cam cover on and i have double double checked it i suppose i will have to start again i am slowly doing it honest ian it seems since i retired i lost the enthusiasm i havnt even been riding my M20 much weather permitting