My 1983 suzuki gr 650 will not start and backfires violently during cranking. timing signal generator looks great and coils are working. fuel system and carburetors seem perfectly operational. any help is great

Get the make and model of the starter, ie Nippon Denso / Hitachi etc go online and do some detective work because most aftermarket sellers list all the fitments. Try ebay, suzuki owners forums, motorcycle swap meets junk sales etc.
I've just been online for a starter and see there are rebuild kits.

you have too much oil in the case, the oil level should appear in the sight glass but not be above half way

Check rubber diaphram of fuel petcock, look for holes or deterioration - if found replace or rebuild the fuel petcock

Because it is a coil and they do burn out. It is nearly 30 years old.

Check the jets in the carb, there might be a blockage there, especially the main jets, check that the needle and seat are allowing the float chamber to fill to the correct level, check that the fuel tap and the in-tank filter are clear of any blockage.

which model & year is your bike? wire spoked wheels or cast alumimium?
have manual on disk, can send you manual. There is more than one wiring diagram in the manual.

look to the solenoid, that clicking you were hearing was it going out,

DRAIN THE OIL OUT OF THE ENGINE AND PULL THE COVER ON THE SIDE OF THE ENGINE THAT IS OPOSITE THE CLUTCH COVER.

ok clyinder quits meaning no spark check your magneeto it tells the coile when to spark it could be off just a little so at higher rpms it wants to cu out there is also a little resistor that might be starting to go bad. if you run it at higher rpms does it cut out? also you can check to see if the coile is getting power set you bike on a block let it hit 60 have some one keep it at 60 and check the coil that will let you know a lot more right there.

it's not right, your mixture could be off, or maybe your timing. did it do it before the carb was re-built