If the carbs have sat, your fuel jets are clogged.
The '78 CB550 I built had round slide carbs. I'm assuming yours are the same?
Anyway, if you are determined to simply see if the bike will fire, do this.
1. Kick it and listen for it to make hollow air-glugging or flapping sounds. This means that the valves are opening and closing and that the resistance you feel isn't just lack of oil. Hahahaha.
2. Assuming the engine DOES have oil in it (regardless if it smells like petrol or paint thinner) then you can start it for a minute but don't rev it, just confirm it's lighting. Do this by pulling the airbox off the carbs and squirting a few DROPS of fuel into the openings.
Leave the airbox and boots off. Squirt tiny drops in, just enough to get it wet, then light it up. Do NOT squirt while turning it over. I use a small syringe with a hypodermic needle that I squared off. It's great for getting a fine stream right inside the carbs without turning it into a lighter-fluid soaked grill ready to flame-broil.
The bike will burn off the vapors from this petrol even if the jets are clogged. I just did this on a Ninja that's acting...like a turd...just as a post-70's bike would.
As mentioned, just replace your cam-chain and cam-chain tensioner face...plate...thing. Very simple rule to live by.
Get an impact driver. Don't ask. Just do it.
Here was my project about one year ago today! Don't ask about the appearance or condition of the bike. I only do what I'm paid to do. If you don't want to take advice and you make half-assed payments, you get half-assed work...
