'79 KZ750 high revs upon starting

So, last night I was able to actually start my bike for the first time. However, when it started it revved up so high I had to immediately use the kill switch to shut the thing off. I didn't have a full battery so I couldn't simulate the event again and get the bike started one more time. I did however, notice that the Reg/Rec was unplugged so I plugged that in, not really sure if that had anything to do with it. Backing up a bit, before I got the bike started I used a bit of starting fluid (ether) and let it sit for about 45 minutes. I also let the carbs drain out and plugged them back up and refilled the carbs/fuel line. The person I bought the bike from said he did a recent carb clean. I don't know how reliable that is but at least the thing started! I'm currently charging the batt again and hopefully today after work I will be able to get it going again.
I did have the choke up(engaged) when it revved really high. I have an aux gas tank going straight into the carbs but before I bought that I used the leftover tank gas to try and get it started from who knows how long ago...maybe I need to quickly flush and clean the carbs somehow?
Thoughts?

ALSO
When I turn over the bike and it starts to slowly churn I hear a loud metallic click and then it's like the starter is going but nothing is attached to it. It's like the bike is starting to turn over and then all of a sudden I hear no moving engine parts, a loud metal click, and then a very distinct audible spinning like a flywheel or whatever is not engaged. THOUGHTS?

Thanks for your help!
Chris

Quantify high revs, its normal for these bikes to rev to 3k rpm when cold and full choke. The trick is to once running back the choke off to about 1500 rpm and leave it there until warm. If the revs start to rise again then back it off further.
Regarding the starter issue, it sounds like the starter clutch needs replacing. If its the same as 650/4 it is located deep in the heart of the engine and is most easily done with the engine out but can be done with the bike on its side.
Dont be tempted with a parts kit, they only last a few k miles. Go for a complete new starter clutch.

Hey Warren,

I don't know how high the rpms go to but I would say it was at about 90% total load right off the bat. I don't have any air filters on the carbs if that helps at all, and it hasn't ran in my ownership and don't know when before.

Do you happen to know where to find an entirely new starter clutch?

Thanks,
Chris

What carbs does it have? Is the idle screw screwed too far in?

Starter clutch should be available from z1enterprises. Their website doesn,t appear to list it only the repair kit.

This is what you want but zpower are in the uk. (as am I)
www.z-power.co.uk/starter-clutch-assy-1062

Since you really don't know what has been done to the carbs, it might save time in the long run to take them off and insure that they are clean and properly set up. The factory service manual and folks on this forum can help you through it.
Remove the float bowls and insure that the jets and tiny passageways are perfectly clear.
Reinstall the bowls, and Bench synchronize the carbs.
Use the clear tube method to insure proper fuel level.
Reinstall and do final synchronization.

TexasKZ wrote: Since you really don't know what has been done to the carbs, it might save time in the long run to take them off and insure that they are clean and properly set up. The factory service manual and folks on this forum can help you through it.
Remove the float bowls and insure that the jets and tiny passageways are perfectly clear.
Reinstall the bowls, and Bench synchronize the carbs.
Use the clear tube method to insure proper fuel level.
Reinstall and do final synchronization.

This^^^

Never trust a previous owner (known as PO). Most are hacks and will say anything to make a sale.
Second, if you are going to run pods you need to rejet the carbs.
Third, vacuum leaks are epidemic on old bikes. Replacing the carb boots that attach to the head is money well spent.
Forth, do some maintenance. Make that all the maintenance. When that's all done then try to start the bike. Not before. Most running problems have their root in bad maintenance.

Good luck

Hey thanks everyone, I managed to find the main issue and got the bike started. Looks like the PO had the throttle pulled up tight and wouldn't fully close the throttle body so when it was started the throttle was open about 40% and on top of that I was using the choke too. So, that was fixed and it was still running a bit loud so I adjusted the carb idle screw and it calmed right down. It's still quite loud because the cross member to the exhaust underneath the bike is just non-existant, so that's just open to atmosphere and that's why the video is so loud.
Very excited that it starts, just don't know if the thing shifts or not, going to start another thread probably about that issue. Also, going to probably take apart the whole engine top/bottom and remove everything down to the frame next.
Thanks everyone!

Whoa dude.

It is too early for the nuclear option. Follow Nessism's advice. Once it is running, you can determine if it all needs to come apart. KZ engines are mighty stout and can survive quite a bit of abuse. Getting all the maintenance up to par may be all it needs.

Lol, ok so then I guess the next step is to figure out why I can't shift gears. I would love to try and give it a test drive around the block but need to be able to shift first.
I'm thinking of instead of the full rebuild maybe doing piston rings? I think I at least need to get into the gearbox to see what's going on down there. Plus, I want to paint the engine and the whole bike. Possibly powdercoat the frame. Not sure yet of how much I want to do, and I'm in no real rush other than wanting to ride it. That's probably why I wanted to rip it all apart. I also need to connect everything and buy a bunch of new items like switches, handlebars, tach cluster,. Along with attaching old PO items like the rear brakes, I also want to build a box out of metal for the battery and reg/rec/solenoid, etc.. At the VERY least, the bike needs a good cleaning. I've honestly hit my mark for at least starting the bike. I wanted to see if it ran and it does! That's why I was waiting to go nuclear. I'm honestly not experienced in taking engines apart to the furthest extent I want to but the manual is pretty helpful and I was thinking of bringing the block to a shop for honing/cleaning, etc.. Thoughts?

I'm not positive about that particular model but most KZ's have a neutral finder which prevents shifting unless the bike is rolling.

Shifting into gears - make sure that your clutch is free (plates aren't stuck together) and that the cable is adjusted properly. If the PO is as big a goof with the clutch cable as he was with the carbs I am guessing you will find trouble there.