Just got it, idle problem

So after two weeks of wait for this and that, I finally picked up the new (to me) bike today. 1981 KZ750 LTD.

As per my luck, I blew the main 20A fuse within two hours of riding it. This I'm used to, and I'm pretty sure I can figure it out.

Now, when the fuse blew and the bike stalled, I pulled it over ASAP and then looked down to see gas just pouring out of the little tubes coming out of the float bowls. I'm assuming that they overflowed when the ignition went out (too much gas, and no spark.) Is this the right assumption?

Also, the idle is pretty messed up. It starts and idles fine from cold with full choke, but once warm, it stalls out if the choke is off, or idles at about 4000 with it on. There doesn't seem to be any play in the choke either, sort of on or off. Additionally, if I turn the choke off and keep the idle up manually, I lose any power on the low end. So I've had to keep the choke on. When I slow down or run at low RPMs, I get constant popping out the exhaust. Over 3000 RPM is runs like a rocket though, just gobs of power and no problems, especially at around 6000.

Now, I'm a novice with a wrench, but am I right in thinking that the first thing I should do is try and adjust the idle at the throttle, or should I be looking at the mixture screws on the carbs? Any help would be much appreciated!

[Now, when the fuse blew and the bike stalled, I pulled it over ASAP and then looked down to see gas just pouring out of the little tubes coming out of the float bowls. I'm assuming that they overflowed when the ignition went out (too much gas, and no spark.) Is this the right assumption?]

No, but your close. It sounds to me like the little valves in the carburator that let the gas in (someone else probably knows the technical term) are probably a little gummed up and stuck SLIGHTLY open. Time to rip off those carburators and clean the crap outta them and set the fuel height.

[Also, the idle is pretty messed up. It starts and idles fine from cold with full choke, but once warm, it stalls out if the choke is off, or idles at about 4000 with it on. There doesn't seem to be any play in the choke either, sort of on or off. Additionally, if I turn the choke off and keep the idle up manually, I lose any power on the low end. So I've had to keep the choke on. When I slow down or run at low RPMs, I get constant popping out the exhaust. Over 3000 RPM is runs like a rocket though, just gobs of power and no problems, especially at around 6000.]

If just cleaning your carbs and setting the float height doesn't resolve this problem (my bet is that it will) then look into a full tuneup. You should grab yourself a clymers manual and that'll tell you what that means. You'll want that manual when your cleaning the carbs, too.

NBK

Yeah, I was hoping it wasn't that. The shop I bought the bike from was supposed to have done a complete tune up. I'm pretty sure they did a rush job on it though, and since the problems are most obvious when the bike is well warmed up, I think they just were careless.

I've got a 90 day guarentee on the bike right now, so if they carbs have to come off, it's going back to the shop. I was just hoping it was somthing easy!

Sickboy...definatley take the bike back,Bud...for sure!
Suggest to Them that the carbs need to be cleaned out,and see what They tell You HAS been done.Too bad...get Them to get that bike running with NO problems.If They're going to offer You a 90 day warranty...They're probably just hoping that You will be good-to-go for 90 days,so They don't have to see You or the bike again.That's a common thing when You buy a bike as old as Yours,from a shop...You'll pay more than You would,if You bought it privately(without any warranty...more than likely)...but being as You DID buy it from a shop,and You DID get a 90 day warranty...do NOT let the 90 days expire,before You KNOW that bike is not doing anything that it shouldn't be doing...DO NOT GET HOSED!!!
You can't expect the Shop to make that bike like NEW,but it IS up to Them to see that that bike goes out the door,and perhaps it has to travel 1000 miles right away,out the door!It shouldn't matter even if You DID live 3 blocks away...not the point!...Do They care about Their name??
It's human-nature to not treat something like an old bike,with as much respect as a new one(unless YOU own it,obviously).
Try to ride that bike as MUCH as possible,over the next few months...seriously...Murphy's law...You KNOW what I'm getting at...LOL...don't let it happen,Bud.