Motorcycle Repair: 78 cb 750f, timing advancer, timing curve

Question
the bike will not take throttle under 3 grand but it will idle at 12to 13 hundered.if you goose it it dies until you let off then it R up and hangs at 35 hundred or more. points look good. carbs are clean very clean even the pilots. it has an after market pipe with stock air box good air filter and good intake boots. it has a 160 main just so it idles the stock jet was a 105. and it seems to react better without the accelerator pump but sill not rite. it has good compression about 130psi in all 4 holes and the valves are within spec. do you think it could be the timing advancer?? and if so can i get new springs? what am i missing?????

Answer
The 160 main is pretty big.  I would have thought a 125-130 would have been plenty.  The idle hanging problem is probably the timing advance unit.  Try pinching the loops smaller on the ends of the springs.  It will increase the tension on the springs.  Just don't close them too much or the timing curve won't be right and you'll loose some power.

Regards
Rich