Bike was sitting Now won't start

[QUICKSTRONG]

Originally Posted by alantf

There's no problem with starting the bike with the side stand down. So long as it's in neutral. The safety switch only kicks in (to turn the engine off) if you try to put it in gear with the stand down. This is a safety feature, so you can't ride off with the stand down.:2tup:

I cleaned the a few days ago but just to make sure the carb is not the problem i took the carb to local shop and had them clean it they took it apart and dipped it. put it on the bike still will not start even with the petcock on prime???
So I decided o fix the leaky valve cover so I removed it and now I need to know how to put it back on. what is the little black rubber circle on he side for? What is the purpose of this. What holds it in place? just the pressure from the cover? when I put the valve cover back on do i need to use any rtv or is there a gasket that should be there? All that was there was some residue from what looked like old rtv gasket maker no gasket.
What should I be looking for as far as problems while I have this off. How much more work is it to replace the head gasket as long as I am this far? Any help is appreciated this is my first time with all of this so I am learning as I go.
Thanks