Welcome Andres!
Hey I finally got my bike a 1979 XS650F. Before diving into the electrical issues of the bike I ran a few tests, (motor seems in great shape! w/ 14 psi compresion)
Did you mean 140psi? As 650Skull's mentioned 14psi is extremely low... and I can't even imagine it would run that low...
ran into something I wasn't familiar with whilst cleaning the carburetors and gas tank, there is a connection behind the fuel tank petcock, one on the boot that goes between the motor and the carb, an a few between the heads that are cancelled or not connected to anything.
The one on the carb boot is a vacuum port, designed to go to the petcocks, and draw fuel when the bike is running. If they aren't connected, then you MUST either connect them to the petcocks OR cap them off...or your bike won't run well. You should have one on each side.
The one between the head is likely a breather port for the engine. This doesn't need to connect to anything, but it's a good idea to attach a hose and route it to the airbox (as it was intended) or down to the bottom of the frame so you don't get oil splattering on you.
I got the bike running but it bogs down if I give it a lot of gas. How should these connections go?
You can connect them to your petcocks with small diameter fuel hose or tubing. I am assuming you have the correct gas tank/petcocks...but if this was changed and you don't have vacuum petcocks, then you can simply cap them off.
To be honest the carbs I'm familiar with have the slide conected directly to the cable.
1979's came with Mukini BS38 (CV- Constant Velocity) carbs. You are probably use to the VM style, where the slide is directly connected to the cable/throttle. The BS38's have a different operation and utilize a butterfly valve to allow airflow into the carbs, and then the slides are pushed up via vacuum and magic... needles to say, they work but are a bit more complicated in some ways. However, they do have a lot of tuning ability...which can be good or bad. There is only one throttle cable, and it connects to the left carb...and the right carb is "linked" to the left one. There's a lot of discussion on the carbs within the tech section... but if you got the bike to run, that's a good sign.
I think it would be good to post some pictures of your bike and the parts you're referring to whenever you have a question...so we can see what you're looking at and it may help with the translation/terminology.