Normal Cost To Rebuild/Clean Carbs?

So  i have a 1978 KZ650D and its been sitting for a while. it pops on decel, knock/ping on idle once in a while. the bike ran great after i got it running for a few rides but suddenly today, it kept dying on me and misfires after i came back from eating at a restaurant. it had a bit misfire on idle but bike had plenty of power before eating. there also seems to be a slight gasoline leak near the petcock which i found out that the previous owner had installed a Pingel Power Flo (dunno why you would spend so much money on a petcock...) but the leak was there before it ran bad so im not sure if thats the problem causing it. it sounds as though the bike is running on 3 cylinders??? anyway, if anyone knows what a normal rebuild or cleaning of the carbs should be, please let me know! and if you have anyone in the Las Vegas area who knows how to work on these bikes, let me know on that also! thank you!

Ps. 
I'm also looking to see if anyone can tell me what replacement petcock i can use for this bike. thanks.

A friend that does lots of carbs told me he charges $250 + parts.  I asked him because I was asked to clean a couple of sets from someone on the GS site and I didn't know what to charge.  

Honestly the hardest part to cleaning carbs is getting them off and on. The actual cleaning is pretty straightforward. Plenty of resources available on this site to get it done. 
You can get upside down pretty fast paying for stuff you can do yourself. 

KoreanKZ post=845508"So  i have a 1978 KZ650D and its been sitting for a while. ..."

Drain the tank, drain the float bowls.  Check/clean/replace the fuel filters, install inline filter(s) if there are none.  Fresh fuel.
Report back.

Good Ridin'
slmjim & Z1BEBE

Yeah, I'm with you guys on this, fresh gas and a splash of Heet for starters,  87 octane not the high test stuff.
Maybe a new set of spark plugs that you can check before spending a bunch of time and  money on a carb job
Clean and check the points while you're at it.

The original petcock for that bike had a vacuum shut off, if it has the original carbs on it now there should be a nipple somewhere on the carbs that is plugged , that would be the nipple for the  vacuum line to the petcock. 
I use the original petcock on my 78, it works fine and I don't worry about having to shut off the gas or a sticky float causing a puddle of gas on my garage floor.
They are available used on ebay from time to time and the rebuild kits are also available. 
 

the bike came with a fuel filter inline and i thought about replacing it with a newer one. as for the draining the bowl, is the picture i posted here the procedure you are talking about? and also, the bike seems to wanna die when i blip the throttle a bit fast. i did cycle through couple tanks of gas before it started to act up but will drain and do it again. also what size if the fuel line that goes to the filter? is it s 1/4 inch?

yeah as i mentioned before, it beats me to see someone spending $150 ball park just for a petcock. id rather have the vacuum activated one and just not worry about it. is there a benefit to the Pingel brand that i have currently installed?

The vacuum petcocks will leak fuel into the crankcase when they fail. This can lead to catastrophic damage if the rider tries to start the engine. If the sealing surfaces of the vacuum model are sufficiently pitted, rebuilding will not fix it.

A manual valve, like the Pingel, can last the life of the bike. They almost never leak and are really simple to use.

Surely that Pingel cock just needs a new o ring/seal?

Pringle is good.  You just have to remember to turn it OFF each time you park the bike otherwise it will flow fuel to the float valves and might overpower them while the bike is parked.

I agree that the pringle is a good item andd does appear to need an o-ring or gasket.  Yes just the earlier manual petcock it does need turned off. 

I want to make sure that if you are going to rebuild the vacuum one on the bike make sure you get the right parts.  There are differences between some of them. See below for some pics of them. If you are going to open it up make sure you get the correct parts to rebuild it as they do not mix correctly.

There are tons of variations in OEM petcocks and many, if not post, aftermarket rebuild kits have the wrong parts.  If you can get the proper parts, preferably OEM, and the petcock casting isn't corroded, then you have a good chance at success with rebuilding the original.  I did just that, with OEM parts, for the petcock on my 750 and it turned out great.  I got lucky though because one of the parts inside wasn't available anymore but the original in my petcock was still okay.  For the most part it doesn't pay to mess around though.