Bike will not start for nothing! Help please.

Hello All,

I have tried other forums and have not yet found much luck. Did a quick google search and found this forum hoping for some help from everyone!! So i got a 1977 XR75 for free that supposedly ran when i was parked. Ya ya ya we've all heard that one before. Well is sat for idk i think they said 10 years? Motor was not seized though. Let me tell you what i have done and please advise me on what else i should try. Compression was a solid 35!!! so i did a top end rebuild and had the cylinders honed and purchased new pistons and new rings. Installed and psi is roughly 130 good now it will run right? still no luck. I have ultra sonic cleaned the carb three times now completely diasembling it and ensuring all passages are clear. I have tried start with an air pod and with OEM air box and still nothing. I have checked valves and set them to .002 which is what i read somewhere on this thread. I have ensure that it is top dead center. O on cam sprocket is at 12 o clock piston is all the way up. I have gone as far as removing the advance timing lobe from the inside of the fly wheel and moving it 180 to see if for some reason previous owner has done this. It basically will just act like it wants to start but never get there. It will back fire out of carb at times and it will fire out exhaust at times. Any thoughts?

Thanks alot,
Dylan.