Help 8) I just dont know .....It starts, right now but, idles up- down to a stall, almost then up.... runs ok then backfires and when the clutch is pulled in she cuts out.Or if you just let off the throttle :'(some backfiring, maybe flames too, and she sounds like she is missing every so often ???
  87 dyna muff, pet thingy, cone filter, 155,55 jets, full spacer,just rebuilt motor,cam and chain. New oil and filter.

Those symptoms really smack of valve timing, you did said you did the cam and chain, but lets see what others say....

thats true, the vacuum operated petthingy, when it malfunctions, can give you those symptoms too. Restarts, dies, restarts again.
See if it works on PRI (turned toward the back) thats gravity flow, not dependant on vacuum.

I will chip in again with my thought, if I remember you had float problems didn't you ? it sounds like the the float chamber is filling to slowly,it goes til the fuel runs low,then stops, the fuel very slowly fills the chamber back up and off you go,sounds like you have the wrong float valve (needle) it might be a tad to long,or the the tab that lifts and drops the float is bent out of shape.
If it feels like you are running out of gas ,that will be the problem.

the idle running up&down sounds like a vacuum leak, check the vac port on the carb where the petthingy used to plug in and make sure it is capped, check the carb mounts to ensure you aren't sucking air around them. when the stealership had it recently, did they replace the float and needle&seat? when you replaced the sparkplug, was it fouled? or just a coincidence, that the carb had time to refill, while changing? remind us where you're at, please, for elevation and climate reference.

HI! Cap is new on vac thing   carb is clamped tight ( if I didnt wear it out, in and out too many times) plug was fouled when i gave up and took it to shop.
need to order a float needle and seat, they only had needle  and that alone didnt fix it
float is free moving and no fluid sound when i shake it,
gonna check it again when i take her apart again today
( maybe adjust the float travel)
old time shop just got her to fire up, stealer wont work on one this old trying to save $$ so im still trying to fix her myself.
Im in Florida, 72 and sunny  
new plug last night and she seemed better, then started the idle up and down thing again,so i called it a night. :'(
87 ls 650  pet thingy 155, 55, cone filter, dyna muff,full spacer

I run with 155 main  and 45(i think whatever came with it) and it's a tad rich too, I turn pilot jet air screw out 2 1/2 turn with sporeter muff. It ran hesitate when first started in the morning but as soon the engine warm-up, it run beautiful (that's carburatored engine for you )