I don't build manufacturing at all on my research planets.
At first I put the wheel on 100% manuf. I usually buid a hospital as soon as possible, I save a couple spots for farms and approval and all the rest is labs.
Then when I have already built a few buildings I might start to put some research back but I try to make sure that it doesn't take more than 3 turns per building (i.e. I keep at least 10 manuf point for the first level of buildings)
I always fill up the planet before starting any upgrade, except for the hospital.
When I finish building I go 100% research. When I get a new upgrade I put back enough manuf to build each upgrade in 2-3 turns then back to research etc...